Aflac (AFL) 10-K21 Feb 202019 FY Annual reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2019	Feb. 12, 2020	Jun. 28, 2019
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-07434
Entity Registrant Name	Aflac Incorporated
Entity Incorporation, State or Country Code	GA
Entity Tax Identification Number	58-1167100
Entity Address, Address Line One	1932 Wynnton Road
Entity Address, City or Town	Columbus
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	31999
City Area Code	706
Local Phone Number	323.3431
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 40,396,253,541
Entity Common Stock, Shares Outstanding		722,520,700
Amendment Flag	false
Entity Central Index Key	0000004977
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2019
Documents Incorporated by Reference	Certain information contained in the Notice and Proxy Statement for the Company’s 2020 Annual Meeting of Shareholders is incorporated by reference into Part III hereof.
NEW YORK STOCK EXCHANGE, INC.
Title of 12(b) Security	Common Stock, $.10 Par Value
Trading Symbol	AFL
Security Exchange Name	NYSE

Consolidated Statements of Earn

Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Net premiums, principally supplemental health insurance	$ 18,780	$ 18,677	$ 18,531
Net investment income	3,578	3,442	3,220
Realized investment gains (losses):
Other-than-temporary impairment losses realized and loan loss reserves	(31)	(81)	(37)
Other gains (losses)	(104)	(349)	(114)
Total realized investment gains (losses)	(135)	(430)	(151)
Other income (loss)	84	69	67
Total revenues	22,307	21,758	21,667
Benefits and expenses:
Benefits and claims, net	11,942	12,000	12,181
Acquisition and operating expenses:
Amortization of deferred policy acquisition costs	1,282	1,245	1,132
Insurance commissions	1,321	1,320	1,316
Insurance and other expenses	3,089	2,988	2,780	[1]
Interest expense	228	222	240
Total acquisition and operating expenses	5,920	5,775	5,468
Total benefits and expenses	17,862	17,775	17,649
Earnings before income taxes	4,445	3,983	4,018
Income Tax Expense:
Current	806	1,379	631
Deferred	335	(316)	(1,217)
Total income tax expense	1,141	1,063	(586)
Net earnings	$ 3,304	$ 2,920	$ 4,604
Net earnings per share:
Basic (in dollars per share)	$ 4.45	$ 3.79	$ 5.81
Diluted (in dollars per share)	$ 4.43	$ 3.77	$ 5.77
Weighted-average outstanding common shares used in computing earnings per share (In thousands):
Basic (in shares)	742,414	769,588	792,042
Diluted (in shares)	746,430	774,650	797,861
5.50% subordinated notes due September 2052
Expense on extinguishment of debt			$ 13

[1]	Includes expense of $13 in 2017 for the early extinguishment of debt

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net earnings	$ 3,304	$ 2,920	$ 4,604
Other comprehensive income (loss) before income taxes:
Unrealized foreign currency translation gains (losses) during period	252	232	286
Unrealized gains (losses) on fixed maturity securities:
Unrealized holding gains (losses) on fixed maturity securities during period	5,870	(3,155)	1,731
Reclassification adjustment for realized (gains) losses on fixed maturity securities included in net earnings	(18)	46	2
Unrealized gains (losses) on derivatives during period	(12)	2	1
Pension liability adjustment during period	(85)	(25)	9
Total other comprehensive income (loss) before income taxes	6,007	(2,900)	2,029
Income tax expense (benefit) related to items of other comprehensive income (loss)	1,543	(797)	631
Other comprehensive income (loss), net of income taxes	4,464	(2,103)	1,398
Total comprehensive income (loss)	$ 7,768	$ 817	$ 6,002

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Investments and cash:
Available for sale, fixed maturity securities		$ 91,262	$ 82,895
Held to maturity, fixed maturity securities		30,085	30,318
Equity securities		802	987
Commercial mortgage and other loans		9,569	6,919
Other investments		1,477	787
Cash and cash equivalents		4,896	4,337
Total investments and cash		138,091	126,243
Receivables		828	851
Accrued investment income		772	773
Deferred policy acquisition costs		10,128	9,875
Property and equipment, at cost less accumulated depreciation	[1]	581	443
Other		2,368	2,221
Total assets		152,768	140,406
Policy liabilities:
Future policy benefits		90,335	86,368
Unpaid policy claims		4,659	4,584
Unearned premiums		4,243	5,090
Other policyholders' funds		7,317	7,146
Total policy liabilities		106,554	103,188
Income taxes		5,370	4,020
Payables for return of cash collateral on loaned securities		1,876	1,052
Notes payable and lease obligations	[1]	6,569	5,778
Other		3,440	2,906
Total liabilities		123,809	116,944
Commitments and contingent liabilities (Note 15)
Shareholders' equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2019 and 2018; issued 1,349,309 shares in 2019 and 1,347,540 shares in 2018		135	135
Additional paid-in capital		2,313	2,177
Retained earnings		34,291	31,788
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains (losses)		(1,623)	(1,847)
Unrealized gains (losses) on fixed maturity securities		8,548	4,234
Unrealized gains (losses) on derivatives		(33)	(24)
Pension liability adjustment		(277)	(212)
Treasury stock, at average cost		(14,395)	(12,789)
Total shareholders' equity		28,959	23,462
Total liabilities and shareholders' equity		152,768	140,406
Consolidated Entity Excluding Variable Interest Entities (VIE)
Investments and cash:
Available for sale, fixed maturity securities		86,950	78,429
Variable Interest Entity, Consolidated
Investments and cash:
Available for sale, fixed maturity securities		4,312	4,466
Equity securities		0	160
Commercial mortgage and other loans		7,956	5,528
Other investments	[2]	494	328
Policy liabilities:
Total liabilities		$ 126	$ 102

[1]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2019 related to leases.
[2]	Consists entirely of alternative investments in limited partnerships

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Available for sale, fixed maturity securities, amortized cost		$ 79,371	$ 76,856
Held to maturity, fixed maturity securities, fair value		37,594	36,722
Commercial mortgage and other loans		9,569	6,919
Other investments		$ 1,477	$ 787
Common stock, par value (in dollars per share)		$ 0.10	$ 0.10
Common stock, shares authorized (in shares)		1,900,000	1,900,000
Common stock, shares issued (in shares)		1,349,309	1,347,540
Asset derivatives		$ 482	$ 417
Liability derivatives		586	387
Variable Interest Entity, Consolidated
Available for sale, fixed maturity securities, amortized cost		3,308	3,849
Commercial mortgage and other loans		7,956	5,528
Other investments	[1]	494	328
Asset derivatives	[2]	169	182
Liability derivatives	[2]	126	102
Consolidated Entity Excluding Variable Interest Entities (VIE)
Available for sale, fixed maturity securities, amortized cost		$ 76,063	$ 73,007

[1]	Consists entirely of alternative investments in limited partnerships
[2]	Consists entirely of derivatives

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock
Balance, beginning of period at Dec. 31, 2016	$ 20,482	$ 135	$ 1,908	$ 25,981	$ 2,630	$ (10,172)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	4,604	0	0	4,604	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes	233	0	0	0	233	0
Unrealized gains (losses) on fixed maturity securities during the period, net of income taxes and reclassification adjustments	1,159	0	0	0	1,159	0
Unrealized gains (losses) on derivatives during period, net of income taxes	1	0	0	0	1	0
Pension liability adjustment during period, net of income taxes	5	0	0	0	5	0
Dividends to shareholders	(690)	0	0	(690)	0	0
Exercise of stock options	38	0	38	0	0	0
Share-based compensation	51	0	51	0	0	0
Purchases of treasury stock	(1,391)	0	0	0	0	(1,391)
Treasury stock reissued	106	0	55	0	0	51
Balance, end of period at Dec. 31, 2017	24,598	135	2,052	29,895	4,028	(11,512)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	2,920	0	0	2,920	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes	228	0	0	0	228	0
Unrealized gains (losses) on fixed maturity securities during the period, net of income taxes and reclassification adjustments	(2,316)	0	0	0	(2,316)	0
Unrealized gains (losses) on derivatives during period, net of income taxes	2	0	0	0	2	0
Pension liability adjustment during period, net of income taxes	(17)	0	0	0	(17)	0
Dividends to shareholders	(801)	0	0	(801)	0	0
Exercise of stock options	34	0	34	0	0	0
Share-based compensation	54	0	54	0	0	0
Purchases of treasury stock	(1,317)	0	0	0	0	(1,317)
Treasury stock reissued	77	0	37	0	0	40
Balance, end of period at Dec. 31, 2018	23,462	135	2,177	31,788	2,151	(12,789)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle, net of income taxes	0	0	0	(226)	226	0
Net earnings	3,304	0	0	3,304	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes	224	0	0	0	224	0
Unrealized gains (losses) on fixed maturity securities during the period, net of income taxes and reclassification adjustments	4,314	0	0	0	4,314	0
Unrealized gains (losses) on derivatives during period, net of income taxes	(9)	0	0	0	(9)	0
Pension liability adjustment during period, net of income taxes	(65)	0	0	0	(65)	0
Dividends to shareholders	(801)	0	0	(801)	0	0
Exercise of stock options	29	0	29	0	0	0
Share-based compensation	54	0	54	0	0	0
Purchases of treasury stock	(1,656)	0	0	0	0	(1,656)
Treasury stock reissued	103	0	53	0	0	50
Balance, end of period at Dec. 31, 2019	$ 28,959	$ 135	$ 2,313	$ 34,291	$ 6,615	$ (14,395)

Consolidated Statements of Sh_2

Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Retained earnings
Dividends to shareholders (in dollars per share)	$ 1.08	$ 1.04	$ 0.87

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net earnings	$ 3,304	$ 2,920	$ 4,604
Adjustments to reconcile net earnings to net cash provided by operating activities:
Change in receivables and advance premiums	(32)	(55)	(91)
Capitalization of deferred policy acquisition costs	(1,452)	(1,504)	(1,468)
Amortization of deferred policy acquisition costs	1,282	1,245	1,132
Increase in policy liabilities	2,104	2,343	2,890
Change in income tax liabilities	(244)	64	(1,240)
Realized investment (gains) losses	135	430	151
Other, net	358	571	150
Net cash provided (used) by operating activities	5,455	6,014	6,128
Proceeds from investments sold or matured:
Available-for-sale fixed maturity securities	5,284	7,888	4,680
Equity securities, FV-NI	650	429
Equity securities, available for sale			902
Held-to-maturity fixed maturity securities	622	1,670	2,212
Commercial mortgage and other loans	1,814	936	303
Costs of investments acquired:
Available for sale fixed maturity securities	(6,934)	(9,086)	(9,867)
Equity securities, FV-NI	(347)	(440)
Equity securities, available-for-sale			(446)
Commercial mortgage and other loans	(4,401)	(4,848)	(2,115)
Other investments, net	(653)	(414)	(206)
Settlement of derivatives, net	(9)	(241)	(621)
Cash received (pledged or returned) as collateral, net	926	348	(205)
Other, net	(123)	176	(68)
Net cash provided (used) by investing activities	(3,171)	(3,582)	(5,431)
Cash flows from financing activities:
Purchases of treasury stock	(1,627)	(1,301)	(1,351)
Proceeds from borrowings	615	1,020	1,040
Principal payments under debt obligations	0	(550)	(1,161)
Dividends paid to shareholders	(771)	(793)	(661)
Change in investment-type contracts, net	(1)	(31)	35
Treasury stock reissued	49	58	33
Other, net	22	(19)	0
Net cash provided (used) by financing activities	(1,713)	(1,616)	(2,065)
Effect of exchange rate changes on cash and cash equivalents	(12)	30	0
Net change in cash and cash equivalents	559	846	(1,368)
Cash and cash equivalents, beginning of period	4,337	3,491	4,859
Cash and cash equivalents, end of period	4,896	4,337	3,491
Supplemental disclosures of cash flow information:
Income taxes paid	1,384	998	780
Interest paid	190	181	196
Noncash interest	37	41	44
Impairment losses and loan loss reserves included in realized investment losses	31	81	37
Noncash financing activities:
Lease obligations	132	11	12
Associate stock bonus
Treasury stock issued for:
Treasury stock issued	15	7	29
Shareholder dividend reinvestment
Treasury stock issued for:
Treasury stock issued	30	8	29
Share-based compensation grants
Treasury stock issued for:
Treasury stock issued	$ 5	$ 2	$ 1

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Description of Business Aflac Incorporated (the Parent Company) and its subsidiaries (collectively, the Company) primarily sell supplemental health and life insurance in the United States (U.S.) and Japan. The Company's insurance business is marketed and administered through American Family Life Assurance Company of Columbus (Aflac) in the U.S. and, effective April 1, 2018, through Aflac Life Insurance Japan Ltd. (ALIJ) in Japan. Prior to April 1, 2018, the Company's insurance business was marketed in Japan as a branch of Aflac. The Company’s operations consist of two reportable business segments: Aflac U.S., which includes Aflac, and Aflac Japan, which includes ALIJ. American Family Life Assurance Company of New York (Aflac New York) is a wholly owned subsidiary of Aflac. Most of Aflac's policies are individually underwritten and marketed through independent agents. Additionally, Aflac U.S. markets and administers group products through Continental American Insurance Company (CAIC), branded as Aflac Group Insurance. The Company's insurance operations in the U.S. and Japan service the two markets for the Company's insurance business. Aflac Japan's revenues, including realized gains and losses on its investment portfolio, accounted for 69% of the Company's total revenues in 2019 , compared with 70% in both 2018 and 2017 . The percentage of the Company's total assets attributable to Aflac Japan was 83% at December 31, 2019 , compared with 84% at December 31, 2018 . In November 2019, the Company acquired Argus Holdings, LLC and its subsidiary Argus Dental & Vision, Inc. (Argus), a benefits management organization and national network dental and vision company, which provides a platform for Aflac Dental and Vision. The Company paid $75 million at closing and made an additional commitment of up to $21 million in contingent consideration payable over three years based on the achievement by Argus of certain performance targets. Argus is an addition to the Aflac U.S. segment. Basis of Presentation The Company prepares its financial statements in accordance with U.S. generally accepted accounting principles (U.S. GAAP). These principles are established primarily by the Financial Accounting Standards Board (FASB). In these Notes to the Consolidated Financial Statements, references to U.S. GAAP issued by the FASB are derived from the FASB Accounting Standards Codification TM (ASC). The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates based on currently available information when recording transactions resulting from business operations. The most significant items on the Company's balance sheet that involve a greater degree of accounting estimates and actuarial determinations subject to changes in the future are the valuation of investments and derivatives, deferred policy acquisition costs (DAC), liabilities for future policy benefits and unpaid policy claims, and income taxes. These accounting estimates and actuarial determinations are sensitive to market conditions, investment yields, mortality, morbidity, commission and other acquisition expenses, and terminations by policyholders. As additional information becomes available, or actual amounts are determinable, the recorded estimates will be revised and reflected in operating results. Although some variability is inherent in these estimates, the Company believes the amounts provided are adequate. The consolidated financial statements include the accounts of the Parent Company, its subsidiaries, and those entities required to be consolidated under applicable accounting standards. All material intercompany accounts and transactions have been eliminated. Significant Accounting Policies Foreign Currency Translation: The functional currency of Aflac Japan is the Japanese yen. The Company translates its yen-denominated financial statement accounts into U.S. dollars as follows. Assets and liabilities are translated at end-of-period exchange rates. Realized gains and losses on security transactions are translated at the exchange rate on the trade date of each transaction. Other revenues, expenses, and cash flows are translated using average exchange rates for the period. The resulting currency translation adjustments are reported in accumulated other comprehensive income. The Company includes in earnings the realized currency exchange gains and losses resulting from foreign currency transactions. The Parent Company has designated a majority of its yen-denominated liabilities (notes payable and yen-denominated loans) as non-derivative hedges and from time-to-time may designate certain foreign currency forwards and options as derivative hedges of the foreign currency exposure of the Company's net investment in Aflac Japan. Outstanding principal and related accrued interest on these Parent Company liabilities and the fair value of these derivatives are translated into U.S. dollars at end-of-period exchange rates. Currency translation adjustments and changes in the fair value of these derivatives are recorded as unrealized foreign currency translation gains (losses) in other comprehensive income and are included in accumulated other comprehensive income. Insurance Revenue and Expense Recognition: Substantially all of the supplemental health and life insurance policies the Company issues are classified as long-duration contracts. The contract provisions generally cannot be changed or canceled during the contract period; however, the Company may adjust premiums for supplemental health policies issued in the U.S. within prescribed guidelines and with the approval of state insurance regulatory authorities. Insurance premiums for most of the Company's health and life policies, including cancer, accident, hospital, critical illness, dental, vision, term life, whole life, long-term care and disability, are recognized as revenue over the premium-paying periods of the contracts when due from policyholders. When revenues are reported, the related amounts of benefits and expenses are charged against such revenues, so that profits are recognized in proportion to premium revenues during the period the policies are expected to remain in force. This association is accomplished by means of annual additions to the liability for future policy benefits and the deferral and subsequent amortization of policy acquisition costs. Premiums from the Company's products with limited-pay features, including term life, whole life, WAYS, and child endowment, are collected over a significantly shorter period than the period over which benefits are provided. Premiums for these products are recognized as revenue over the premium-paying periods of the contracts when due from policyholders. Any gross premium in excess of the net premium is deferred and recorded in earnings, such that profits are recognized in a constant relationship with insurance in force. Benefits are recorded as an expense when they are incurred. A liability for future policy benefits is recorded when premiums are recognized using the net premium method. At the policyholder's option, customers can also pay discounted advanced premiums for certain of the Company's products. Advanced premiums are deferred and recognized when due from policyholders over the regularly scheduled premium payment period. The calculation of DAC and the liability for future policy benefits requires the use of estimates based on sound actuarial valuation techniques. For new policy issues, the Company reviews its actuarial assumptions and deferrable acquisition costs each year and revises them when necessary to more closely reflect recent experience and studies of actual acquisition costs. For policies in force, the Company evaluates DAC by major product groupings to determine that they are recoverable from future revenues, and any amounts determined not to be recoverable are charged against net earnings. The Company has not had any material charges to earnings for DAC that was determined not to be recoverable in any of the years presented in this Form 10-K. Advertising expense is reported as incurred in insurance expenses in the consolidated statements of earnings. Cash and Cash Equivalents: Cash and cash equivalents include cash on hand, money market instruments, and other debt instruments with a maturity of 90 days or less when purchased. Investments: The Company's debt securities consist of fixed maturity securities, which are classified as either held to maturity or available for sale. Securities classified as held to maturity are securities that the Company has the ability and intent to hold to maturity or redemption and are carried at amortized cost. All other fixed maturity debt securities are classified as available for sale and are carried at fair value. If the fair value is higher than the amortized cost for debt securities, the excess is an unrealized gain, and if lower than cost, the difference is an unrealized loss. The net unrealized gains and losses on securities available for sale, less related deferred income taxes, are recorded through other comprehensive income and included in accumulated other comprehensive income. Amortized cost of debt securities is based on the Company's purchase price adjusted for accrual of discount, or amortization of premium, and recognition of impairment charges, if any. The amortized cost of debt securities the Company purchases at a discount or premium will equal the face or par value at maturity or the call date, if applicable. Interest is reported as income when earned and is adjusted for amortization of any premium or discount. The Company has investments in marketable equity securities which are carried at fair value. Changes in the fair value of equity securities are recorded in earnings as a component of realized investment gains and losses. The Company has investments in variable interest entities (VIEs). Criteria for evaluating VIEs for consolidation focuses on identifying which enterprise has the power to direct the activities of a variable interest entity that most significantly impact the entity's economic performance and (1) the obligation to absorb losses of the entity or (2) the right to receive benefits from the entity. The Company is the primary beneficiary of certain VIEs, and therefore consolidates these entities in its financial statements. While the consolidated VIEs generally operate within a defined set of contractual terms, there are certain powers that are retained by the Company that are considered significant in the conclusion that the Company is the primary beneficiary. These powers vary by structure but generally include the initial selection of the underlying collateral; the ability to obtain the underlying collateral in the event of default; and, the ability to appoint or dismiss key parties in the structure. In particular, the Company's powers surrounding the underlying collateral were considered to be the most significant powers because those most significantly impact the economics of the VIE. The Company has no obligation to provide any continuing financial support to any of the entities in which it is the primary beneficiary. The Company's maximum loss is limited to its original investment. Neither the Company nor any of its creditors have the ability to obtain the underlying collateral, nor does the Company have control over the instruments held in the VIEs, unless there is an event of default. For those entities where the Company is the primary beneficiary, the consolidated entity's assets are segregated on the balance sheet by the caption "consolidated variable interest entities," and consist of fixed maturity securities, equity securities, loan receivables, limited partnerships and derivative instruments. For the mortgage- and asset-backed securities held in the Company's fixed maturity portfolio, the Company recognizes income using a constant effective yield, which is based on anticipated prepayments and the estimated economic life of the securities. When estimates of prepayments change, the effective yield is recalculated to reflect actual payments to date and anticipated future payments. The net investment in mortgage- and asset-backed securities is adjusted to the amount that would have existed had the new effective yield been applied at the time of acquisition. This adjustment is reflected in net investment income. The Company uses the specific identification method to determine the gain or loss from securities transactions and report the realized gain or loss in the consolidated statements of earnings. Securities transactions are accounted for based on values as of the trade date of the transaction. An investment in a fixed maturity security is impaired if the fair value falls below amortized cost. The Company regularly reviews its fixed maturity security investments portfolio for declines in fair value. The Company's fixed maturity security investments are evaluated for other-than-temporary impairment using its debt impairment model. The Company's debt impairment model focuses on the ultimate collection of the cash flows from its investments and whether the Company has the intent to sell or if it is more likely than not the Company would be required to sell the security prior to recovery of its amortized cost. The determination of the amount of impairments under this model is based upon the Company's periodic evaluation and assessment of known and inherent risks associated with the respective securities. Such evaluations and assessments are revised as conditions change and new information becomes available. When determining the Company's intention to sell a security prior to recovery of its fair value to amortized cost, the Company evaluates facts and circumstances such as, but not limited to, future cash flow needs, decisions to reposition its security portfolio, and risk profile of individual investment holdings. The Company performs ongoing analyses of its liquidity needs, which includes cash flow testing of its policy liabilities, debt maturities, projected dividend payments, and other cash flow and liquidity needs. The determination of whether an impairment in value of the Company's fixed maturity securities is other than temporary is based largely on the Company's evaluation of the issuer ' s creditworthiness. The Company must apply considerable judgment in determining the likelihood of its fixed maturity securities recovering in value. Factors that may influence this include the overall level of interest rates, credit spreads, the credit quality of the underlying issuer, and other factors. This process requires consideration of risks which can be controlled to a certain extent, such as credit risk, and risks which cannot be controlled, such as interest rate risk and foreign currency risk. If, after monitoring and analyses, management believes that fair value will not recover to amortized cost, the Company recognizes an other-than-temporary impairment of the security. Once a security is considered to be other-than-temporarily impaired, the impairment loss is separated into two components: the portion of the impairment related to credit and the portion of the impairment related to factors other than credit. The Company recognizes a charge to earnings for the credit-related portion of other-than-temporary impairments. Impairments related to factors other than credit are charged to earnings in the event the Company intends to sell the security prior to the recovery of its amortized cost or if it is more likely than not that the Company would be required to dispose of the security prior to recovery of its amortized cost; otherwise, non-credit-related other-than-temporary impairments are charged to other comprehensive income. The Company lends fixed maturity and public equity securities to financial institutions in short-term security-lending transactions. These securities continue to be carried as investment assets on the Company's balance sheet during the terms of the loans and are not reported as sales. The Company receives cash or other securities as collateral for such loans. For loans involving unrestricted cash or securities as collateral, the collateral is reported as an asset with a corresponding liability for the return of the collateral. For loans where the Company receives as collateral securities that the Company is not permitted to sell or repledge, the collateral is not reported as an asset. Commercial mortgage and other loans include transitional real estate loans (TREs), commercial mortgage loans (CMLs) and middle market loans (MMLs). The Company's investments in TREs, CMLs, and MMLs are accounted for as loan receivables and are recorded at amortized cost on the acquisition date. The Company has the intent and ability to hold these loan receivables for the foreseeable future or until they mature and therefore, they are considered held for investment and are carried at amortized cost in the commercial mortgage and other loans line in its consolidated balance sheets. The amortized cost of the loan receivables reflects allowances for expected incurred losses estimated based on past events and current economic conditions as of each reporting date. Other investments include policy loans, limited partnerships, and short-term investments with maturities at the time of purchase of one year or less, but greater than 90 days. Limited partnerships are accounted for using the equity method of accounting. Under the equity method of accounting, the Company reports its portion of partnership earnings as a component of net investment income in its consolidated statements of earnings. The underlying investments held by the Company’s limited partnerships primarily consist of private equity and real estate. Short-term investments are stated at amortized cost, which approximates fair value. Derivatives and Hedging: Freestanding derivative instruments are reported in the consolidated balance sheet at fair value and are reported in other assets and other liabilities, with changes in value reported in earnings and/or other comprehensive income. These freestanding derivatives are foreign currency forwards, foreign currency options, foreign currency swaps, interest rate swaps, interest rate swaptions, and, in prior year periods, credit default swaps (CDSs). The Company does not use derivatives for trading purposes, nor does the Company engage in leveraged derivative transactions. From time to time, the Company purchases certain investments that contain an embedded derivative. The Company assesses whether this embedded derivative is clearly and closely related to the asset that serves as its host contract. If the Company deems that the embedded derivative's terms are not clearly and closely related to the host contract, and a separate instrument with the same terms would qualify as a derivative instrument, the derivative is separated from that contract, held at fair value, and reported with the host instrument in the consolidated balance sheet, with changes in fair value reported in earnings. If the Company has elected the fair value option, the embedded derivative is not bifurcated, and the entire investment is held at fair value with changes in fair value reported in earnings. See Note 5 for a discussion on how the Company determines the fair value of its derivatives. Accruals on derivatives are typically recorded in other assets or within other liabilities in the consolidated balance sheets. To qualify for hedge accounting treatment, a derivative must be highly effective in mitigating the designated risk attributable to the hedged item. At the inception of hedging relationships the Company formally documents all relationships between hedging instruments and hedged items, as well as its risk-management objectives and strategies for undertaking the respective hedging relationship, and the methodology that will be used to assess the effectiveness of the hedge relationship at and subsequent to hedge inception. The Company documents the designation of each hedge as either (i) a hedge of the variability of cash flows to be received or paid related to a recognized asset or liability or the hedge of a forecasted transaction ("cash flow hedge"); (ii) a hedge of the estimated fair value of a recognized asset or liability ("fair value hedge"); or (iii) a hedge of a net investment in a foreign operation. The documentation process includes linking derivatives and non-derivative financial instruments that are designated as hedges to specific assets or groups of assets or liabilities in the statement of financial position or to specific forecasted transactions and defining the effectiveness testing methods to be used. At the hedge inception and on an ongoing quarterly basis, the Company also formally assesses whether the derivatives and non-derivative financial instruments used in hedging activities have been, and are expected to continue to be, highly effective in offsetting their designated risk. Hedge effectiveness is assessed using qualitative and quantitative methods. The assessment of hedge effectiveness determines the accounting treatment of changes in fair value. For assessing hedge effectiveness, qualitative methods may include the comparison of critical terms of the derivative to the hedged item, and quantitative methods may include regression, dollar offset, or other statistical analysis of changes in fair value or cash flows associated with the hedge relationship. For derivative instruments that are designated and qualify as cash flow hedges, the gain or loss on the derivative is reported as a component of other comprehensive income (loss) and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. In cash flow hedges, all components of each derivative's gain or loss are included in the assessment of hedge effectiveness. For derivative instruments that are designated and qualify as fair value hedges, the gain or loss on the hedged item and the portion of the hedging instrument included in the assessment of effectiveness are recorded in the line item of the consolidated statements of earnings in which gain or loss on the hedged item is recorded. When assessing the effectiveness of the Company's fair value hedges, the Company excludes the changes in fair value related to the difference between the spot and the forward rate on its foreign currency forwards and the time value of money of foreign exchange options and interest rate swaptions. For interest rate swaptions designated under fair value hedges of interest rate risk, the change in the time value of money is recognized in other comprehensive income (loss) and amortized into earnings (net investment income) over its legal term. As discussed in Note 4, from time to time the Company designates net investment hedges of its net investment in Aflac Japan. The Company makes its net investment hedge designation at the beginning of each quarter. For derivative hedging instruments designated as net investment hedges, Aflac follows the spot-rate method. According to that method, the change in fair value of the hedging instrument due to fluctuations in the spot exchange rate is recorded in the unrealized foreign currency component of other comprehensive income and reclassified to earnings only when the hedged net investment is sold, or when a liquidation of the respective net investment in the foreign entity is substantially completed. If and when a sale or liquidation occurs, the changes in fair value of the derivative deferred in the unrealized foreign currency component of other comprehensive income will be released in the same income statement line item where the gain (loss) on the hedged net investment would be recorded upon sale. All other changes in fair value of the hedging instrument are considered the “excluded component” and are accounted for in realized investment gains (losses). Should these designated net investment hedge positions exceed the Company's net investment in Aflac Japan, the foreign exchange effect on the portion that exceeds its investment in Aflac Japan would be recognized in current earnings within realized investment gains (losses). The Company discontinues hedge accounting prospectively when (1) it is determined that the derivative is no longer highly effective in offsetting changes in the estimated cash flows or fair value of a hedged item; (2) the derivative is de-designated as a hedging instrument; or (3) the derivative expires or is sold, terminated or exercised. When hedge accounting is discontinued on a cash flow hedge or fair value hedge, the derivative is carried in the consolidated balance sheets at its estimated fair value, with changes in estimated fair value recognized in current period earnings. For discontinued cash flow hedges, including those where the derivative is sold, terminated or exercised, amounts previously deferred in other comprehensive income (loss) are reclassified into earnings when earnings are impacted by the cash flow of the hedged item. If a derivative is not designated as an accounting hedge or its use in managing risk does not qualify for hedge accounting, changes in the estimated fair value of the derivative are generally reported within other gains (losses), which is a component of realized investment gains (losses). The fluctuations in estimated fair value of derivatives that have not been designated for hedge accounting can result in volatility in net earnings. The Company receives and pledges cash or other securities as collateral on open derivative positions. Cash received as collateral is reported as an asset with a corresponding liability for the return of the collateral. Cash pledged as collateral is recorded as a reduction to cash, and a corresponding receivable is recognized for the return of the cash collateral. The Company generally can repledge or resell collateral obtained from counterparties, although the Company does not typically exercise such rights. Securities received as collateral are not recognized unless the Company was to exercise its right to sell that collateral or exercise remedies on that collateral upon a counterparty default. Securities that the Company has pledged as collateral continue to be carried as investment assets on its balance sheet. Deferred Policy Acquisition Costs: Certain direct and incremental costs of acquiring new business are deferred and amortized with interest over the premium payment periods in proportion to the ratio of annual premium income to total anticipated premium income. Anticipated premium income is estimated by using the same mortality, persistency and interest assumptions used in computing liabilities for future policy benefits. In this manner, the related acquisition expenses are matched with revenues. Deferred costs include the excess of current-year commissions over ultimate renewal-year commissions and certain incremental direct policy issue, underwriting and sales expenses. All of these incremental costs are directly related to successful policy acquisition. For some products, policyholders can elect to modify product benefits, features, rights or coverages by exchanging a contract for a new contract or by amendment, endorsement, or rider to a contract, or by the election of a feature or coverage within a contract. These transactions are known as internal replacements. The Company performs a two-stage analysis of the internal replacements to determine if the modification is substantive to the base policy. The stages of evaluation are as follows: 1) determine if the modification is integrated with the base policy, and 2) if it is integrated, determine if the resulting contract is substantially changed. For internal replacement transactions where the resulting contract is substantially unchanged, the policy is accounted for as a continuation of the replaced contract. Unamortized deferred acquisition costs from the original policy continue to be amortized over the expected life of the new policy, and the costs of replacing the policy are accounted for as policy maintenance costs and expensed as incurred. Examples include conversions of same age bands, certain family coverage changes, pricing era changes (decrease), and ordinary life becomes reduced paid-up and certain reinstatements. An internal replacement transaction that results in a policy that is substantially changed is accounted for as an extinguishment of the original policy and the issuance of a new policy. Unamortized deferred acquisition costs on the original policy are immediately expensed, and the costs of acquiring the new policy are capitalized and amortized in accordance with the Company's accounting policies for deferred acquisition costs. Further, the policy reserves are evaluated based on the new policy features, and any change (up or down) necessary is recognized at the date of contract change/modification. Examples include conversions to higher age bands, certain family coverage changes, pricing era changes (increase), lapse & re-issue, certain reinstatements and certain other contract conversions. Riders can be considered internal replacements that are either integrated or non-integrated resulting in either substantially changed or substantially unchanged treatment. Riders are evaluated based on the specific facts and circumstances of the rider and are considered an expansion of the existing benefits with additional premium required. Non-integrated riders to existing contracts do not change the Company's profit expectations for the related products and are treated as a new policy establishment for incremental coverage. The Company measures the recoverability of DAC and the adequacy of its policy reserves annually by performing gross premium valuations on its business. (See the following discussion for further information regarding policy reserves.) Policy Liabilities: Future policy benefits represent claims that are expected to occur in the future and are computed following a net level premium method using estimated future investment yields, persistency and recognized morbidity and mortality tables modified to reflect the Company's experience, including a provision for adverse deviation. These assumptions are generally established and considered locked at policy inception. These assumptions may only be unlocked in certain circumstances based on the results of periodic DAC recoverability and premium deficiency testing. Unpaid policy claims are estimates computed primarily on an undiscounted basis using statistical analyses of historical claims experience adjusted for current trends and changed conditions. The ultimate liability may vary significantly from such estimates. The Company regularly adjusts these estimates as new claims experience emerges and reflects the changes in operating results in the year such adjustments are made. Unearned premiums consist primarily of discounted advance premiums on deposit from policyholders in conjunction with their purchase of certain Aflac Japan limited-pay insurance products. These advanced premiums are deferred upon collection and recognized as premium revenue over the contractual premium payment period. Other policyholders’ funds liability consists primarily of the fixed annuity line of business in Aflac Japan which has fixed benefits and premiums. For internal replacements that are determined to not be substantially unchanged, policy liabilities related to the original policy that was replaced are immediately released, and policy liabilities are established for the new insurance contract; however, for internal replacements that are considered substantially unchanged, no changes to the reserves are recognized. Reinsurance: The Company enters into reinsurance agreements with other companies in the normal course of business. For each reinsurance agreement, the Company determines if the agreement provides indemnification against loss or liability relating to insurance risk in accordance with applicable accounting standards. Reinsurance premiums and benefits paid or provided are accounted for on bases consistent with those used in accounting for the original policies issued and the terms of the reinsurance contracts. Premiums, benefits and DAC are reported net of insurance ceded. Income Taxes: Income tax provisions are generally based on pretax earnings reported for financial statement purposes, which differ from those amounts used in preparing the Company's income tax returns. Deferred income taxes are recognized for temporary differences between the financial reporting ba

BUSINESS SEGMENT AND FOREIGN IN

BUSINESS SEGMENT AND FOREIGN INFORMATION	12 Months Ended
BUSINESS SEGMENT AND FOREIGN INFORMATION	Dec. 31, 2019
Segment Reporting [Abstract]
BUSINESS SEGMENT INFORMATION	BUSINESS SEGMENT AND FOREIGN INFORMATION The Company consists of two reportable insurance business segments: Aflac Japan and Aflac U.S., both of which sell supplemental health and life insurance. In addition, operating business units that are not individually reportable and business activities, including reinsurance retrocession activities, not included in Aflac Japan or Aflac U.S. are included in Corporate and other. The Company does not allocate corporate overhead expenses to business segments. Consistent with U.S. GAAP accounting guidance for segment reporting, the Company evaluates and manages its business segments using a financial performance measure called pretax adjusted earnings. Adjusted earnings are adjusted revenues less benefits and adjusted expenses. The adjustments to both revenues and expenses account for certain items that cannot be predicted or that are outside management’s control. Adjusted revenues are U.S. GAAP total revenues excluding realized investment gains and losses, except for amortized hedge costs/income related to foreign currency exposure management strategies and net interest cash flows from derivatives associated with certain investment strategies. Adjusted expenses are U.S. GAAP total acquisition and operating expenses including the impact of interest cash flows from derivatives associated with notes payable but excluding any nonrecurring or other items not associated with the normal course of the Company’s insurance operations and that do not reflect Aflac’s underlying business performance. The Company excludes income taxes related to operations to arrive at pretax adjusted earnings. Information regarding operations by reportable segment and Corporate and other for the years ended December 31 follows: (In millions) 2019 2018 2017 Revenues: Aflac Japan: Net earned premiums: Cancer $ 6,031 $ 5,849 $ 5,612 Medical and other health 3,582 3,516 3,379 Life insurance 3,159 3,397 3,761 Net investment income, less amortized hedge costs (1),(2) 2,496 2,403 2,235 Other income 45 41 41 Total Aflac Japan 15,313 15,206 15,028 Aflac U.S.: Net earned premiums: Accident/disability 2,665 2,611 2,537 Cancer 1,309 1,311 1,308 Other health 1,548 1,508 1,445 Life insurance 286 278 273 Net investment income 720 727 721 Other income 22 8 5 Total Aflac U.S. 6,550 6,443 6,289 Corporate and other (3) 393 339 272 Total adjusted revenues 22,256 21,988 21,589 Realized investment gains (losses) (1),(2),(3) 51 (230 ) 78 Total revenues $ 22,307 $ 21,758 $ 21,667 (1) Amortized hedge costs of $257 , $236 and $228 in 2019 , 2018 and 2017 , respectively, related to certain foreign currency exposure management strategies have been reclassified from realized investment gains (losses) and reported as a deduction from net investment income when analyzing operations. (2) Net interest cash flows from derivatives associated with certain investment strategies of $(17) in 2019 and an immaterial amount in 2018 have been reclassified from realized investment gains (losses) and included in adjusted earnings as a component of net investment income. (3) Amortized hedge income of $89 in 2019 and $36 in 2018 related to certain foreign currency exposure management strategies has been reclassified from realized investment gains (losses) and reported as an increase to net investment income when analyzing operations. (In millions) 2019 2018 2017 Pretax earnings: Aflac Japan (1),(2) $ 3,261 $ 3,208 $ 3,054 Aflac U.S. 1,272 1,285 1,245 Corporate and other (3),(4) (72 ) (139 ) (212 ) Pretax adjusted earnings (5) 4,461 4,354 4,087 Realized investment gains (losses) (1),(2),(3),(4) (15 ) (297 ) 0 Other income (loss) (6) (1 ) (74 ) (69 ) Total earnings before income taxes $ 4,445 $ 3,983 $ 4,018 Income taxes applicable to pretax adjusted earnings $ 1,147 $ 1,129 $ 1,370 Effect of foreign currency translation on after-tax 15 28 (41 ) (1) Amortized hedge costs of $257 , $236 and $228 in 2019 , 2018 and 2017 , respectively, related to certain foreign currency exposure management strategies have been reclassified from realized investment gains (losses) and reported as a deduction from net investment income when analyzing operations. (2) Net interest cash flows from derivatives associated with certain investment strategies of $(17) in 2019 and an immaterial amount in 2018 have been reclassified from realized investment gains (losses) and included in adjusted earnings as a component of net investment income. (3) Amortized hedge income of $89 in 2019 and $36 in 2018 related to certain foreign currency exposure management strategies has been reclassified from realized investment gains (losses) and reported as an increase to net investment income when analyzing operations. (4) A gain of $66 in 2019 , $67 in 2018 and $77 in 2017 , related to the interest rate component of the change in fair value of foreign currency swaps on notes payable have been reclassified from realized investment gains (losses) and included in adjusted earnings when analyzing operations. (5) Includes $135 , $122 and $122 of interest expense on debt in 2019 , 2018 and 2017 (6) Includes expense of $13 in 2017 for the early extinguishment of debt Assets as of December 31 were as follows: (In millions) 2019 2018 Assets: Aflac Japan $ 127,523 $ 118,342 Aflac U.S. 20,945 19,100 Corporate and other 4,300 2,964 Total assets $ 152,768 $ 140,406 Yen-Translation Effects: The following table shows the yen/dollar exchange rates used for or during the periods ended December 31 . Exchange effects were calculated using the same yen/dollar exchange rate for the current year as for each respective prior year. 2019 2018 2017 Statements of Earnings: Weighted-average yen/dollar exchange rate (1) 109.07 110.39 112.16 Yen percent strengthening (weakening) 1.2 % 1.6 % (3.1 )% Exchange effect on pretax adjusted earnings (in millions) $ 20 $ 38 $ (63 ) 2019 2018 Balance Sheets: Yen/dollar exchange rate at December 31 (1) 109.56 111.00 Yen percent strengthening (weakening) 1.3 % 1.8 % Exchange effect on total assets (in millions) $ 1,225 $ 1,362 Exchange effect on total liabilities (in millions) 1,533 1,270 (1) Rates are based on the published MUFG Bank, Ltd. telegraphic transfer middle rate (TTM) Transfers of funds from Aflac Japan: Aflac Japan makes payments to the Parent Company for management fees, allocated expenses and remittances of earnings. Prior to the Aflac Japan branch conversion on April 1, 2018, Aflac Japan paid allocated expenses and profit remittances to Aflac U.S. Information on transfers for each of the years ended December 31 is shown below. See Note 13 for information concerning restrictions on transfers from Aflac Japan. (In millions) 2019 2018 2017 Management fees $ 75 $ 136 $ 93 Allocated expenses 4 24 109 Profit remittances 2,070 808 1,150 Total transfers from Aflac Japan $ 2,149 $ 968 $ 1,352 Property and Equipment: The costs of buildings, furniture and equipment are depreciated principally on a straight-line basis over their estimated useful lives (maximum of 50 years for buildings and 20 years for furniture and equipment). Expenditures for maintenance and repairs are expensed as incurred; expenditures for betterments are capitalized and depreciated. Classes of property and equipment as of December 31 were as follows: (In millions) 2019 2018 Property and equipment: Land $ 168 $ 168 Buildings 473 456 Equipment and furniture 549 400 Total property and equipment 1,190 1,024 Less accumulated depreciation 609 581 Net property and equipment $ 581 $ 443 Receivables: Receivables consist primarily of monthly insurance premiums due from individual policyholders or their employers for payroll deduction of premiums, net of an allowance for doubtful accounts. At December 31, 2019 , $258 million , or 31.2% of total receivables, were related to Aflac Japan's operations, compared with $334 million , or 39.2% , at December 31, 2018 .

INVESTMENTS

INVESTMENTS	12 Months Ended
INVESTMENTS	Dec. 31, 2019
Investments [Abstract]
INVESTMENTS	INVESTMENTS Net Investment Income The components of net investment income for the years ended December 31 were as follows: (In millions) 2019 2018 2017 Fixed maturity securities $ 3,141 $ 3,142 $ 3,173 Equity securities 37 38 42 Commercial mortgage and other loans 468 333 86 Other investments 53 36 8 Short-term investments and cash equivalents 56 41 25 Gross investment income 3,755 3,590 3,334 Less investment expenses 177 148 114 Net investment income $ 3,578 $ 3,442 $ 3,220 Investment Holdings The amortized cost for the Company's investments in fixed maturity securities, the cost for equity securities and the fair values of these investments at December 31 are shown in the following tables. 2019 (In millions) Cost or Gross Gross Fair Securities available for sale, carried at fair value Fixed maturity securities: Yen-denominated: Japan government and agencies $ 30,929 $ 5,169 $ 0 $ 36,098 Municipalities 516 116 3 629 Mortgage- and asset-backed securities 229 25 0 254 Public utilities 1,855 406 0 2,261 Sovereign and supranational 680 50 0 730 Banks/financial institutions 6,152 700 86 6,766 Other corporate 5,323 944 24 6,243 Total yen-denominated 45,684 7,410 113 52,981 U.S. dollar-denominated: U.S. government and agencies 293 9 0 302 Municipalities 1,077 141 0 1,218 Mortgage- and asset-backed securities 149 7 0 156 Public utilities 3,804 725 10 4,519 Sovereign and supranational 239 73 0 312 Banks/financial institutions 2,879 646 4 3,521 Other corporate 25,246 3,255 248 28,253 Total U.S. dollar-denominated 33,687 4,856 262 38,281 Total securities available for sale $ 79,371 $ 12,266 $ 375 $ 91,262 2018 (In millions) Cost or Gross Gross Fair Securities available for sale, carried at fair value Fixed maturity securities: Yen-denominated: Japan government and agencies $ 30,637 $ 3,700 $ 140 $ 34,197 Municipalities 385 32 9 408 Mortgage- and asset-backed securities 155 22 0 177 Public utilities 1,732 280 4 2,008 Sovereign and supranational 826 123 0 949 Banks/financial institutions 5,440 502 238 5,704 Other corporate 4,852 649 44 5,457 Total yen-denominated 44,027 5,308 435 48,900 U.S dollar-denominated: U.S. government and agencies 137 9 1 145 Municipalities 1,343 120 8 1,455 Mortgage- and asset-backed securities 155 8 1 162 Public utilities 4,772 496 105 5,163 Sovereign and supranational 251 60 0 311 Banks/financial institutions 2,860 389 35 3,214 Other corporate 23,311 1,343 1,109 23,545 Total U.S. dollar-denominated 32,829 2,425 1,259 33,995 Total securities available for sale $ 76,856 $ 7,733 $ 1,694 $ 82,895 2019 (In millions) Cost or Gross Gross Fair Securities held to maturity, carried at amortized cost: Fixed maturity securities: Yen-denominated: Japan government and agencies $ 22,241 $ 6,050 $ 0 $ 28,291 Municipalities 821 262 0 1,083 Mortgage- and asset-backed securities 16 1 0 17 Public utilities 2,535 419 0 2,954 Sovereign and supranational 1,123 197 0 1,320 Banks/financial institutions 916 105 3 1,018 Other corporate 2,433 485 7 2,911 Total yen-denominated 30,085 7,519 10 37,594 Total securities held to maturity $ 30,085 $ 7,519 $ 10 $ 37,594 2018 (In millions) Cost or Gross Gross Fair Securities held to maturity, carried at amortized cost: Fixed maturity securities: Yen-denominated: Japan government and agencies $ 21,712 $ 5,326 $ 0 $ 27,038 Municipalities 359 110 0 469 Mortgage- and asset-backed securities 14 1 0 15 Public utilities 2,727 254 8 2,973 Sovereign and supranational 1,551 289 0 1,840 Banks/financial institutions 1,445 158 20 1,583 Other corporate 2,510 332 38 2,804 Total yen-denominated 30,318 6,470 66 36,722 Total securities held to maturity $ 30,318 $ 6,470 $ 66 $ 36,722 2019 2018 (In millions) Fair Value Fair Value Equity securities, carried at fair value through net earnings: Equity securities: Yen-denominated $ 658 $ 641 U.S. dollar-denominated 144 346 Total equity securities $ 802 $ 987 The methods of determining the fair values of the Company's investments in fixed maturity securities and equity securities are described in Note 5. During 2019 and 2018, the Company did not reclassify any investments from the held-to-maturity category to the available-for-sale category. During 2017, the Company reclassified three investments from the held-to-maturity category to the available-for-sale category as a result of the issuers' credit rating being downgraded to below investment grade. At the time of the transfer, the securities had an aggregate amortized cost of $773 million and an aggregate unrealized gain of $47 million Contractual and Economic Maturities The contractual and economic maturities of the Company's investments in fixed maturity securities at December 31, 2019 , were as follows: (In millions) Amortized Fair Available for sale: Due in one year or less $ 583 $ 612 Due after one year through five years 7,933 8,122 Due after five years through 10 years 11,347 12,819 Due after 10 years 59,130 69,299 Mortgage- and asset-backed securities 378 410 Total fixed maturity securities available for sale $ 79,371 $ 91,262 Held to maturity: Due in one year or less $ 265 $ 270 Due after one year through five years 1,227 1,330 Due after five years through 10 years 532 599 Due after 10 years 28,045 35,378 Mortgage- and asset-backed securities 16 17 Total fixed maturity securities held to maturity $ 30,085 $ 37,594 Investment Concentrations The Company's process for investing in credit-related investments begins with an independent approach to underwriting each issuer's fundamental credit quality. The Company evaluates independently those factors that it believes could influence an issuer's ability to make payments under the contractual terms of the Company's instruments. This includes a thorough analysis of a variety of items including the issuer's country of domicile (including political, legal, and financial considerations); the industry in which the issuer competes (with an analysis of industry structure, end-market dynamics, and regulation); company specific issues (such as management, assets, earnings, cash generation, and capital needs); and contractual provisions of the instrument (such as financial covenants and position in the capital structure). The Company further evaluates the investment considering broad business and portfolio management objectives, including asset/liability needs, portfolio diversification, and expected income. Investment exposures that individually exceeded 10% of shareholders' equity as of December 31 were as follows: 2019 2018 (In millions) Credit Amortized Fair Credit Amortized Fair Japan National Government (1) A+ $51,726 $62,584 A+ $51,207 $59,945 (1) Japan Government Bonds (JGBs) or JGB-backed securities Realized Investment Gains and Losses Information regarding pretax realized gains and losses from investments for the years ended December 31 follows: (In millions) 2019 2018 2017 Realized investment gains (losses): Fixed maturity securities: Available for sale: Gross gains from sales $ 115 $ 101 $ 51 Gross losses from sales (68 ) (156 ) (68 ) Foreign currency gains (losses) on sales and redemptions (16 ) 73 (48 ) Other-than-temporary impairment losses (13 ) (64 ) (7 ) Total fixed maturity securities 18 (46 ) (72 ) Equity securities 101 (131 ) 71 (1) Loan receivables: Loan loss reserves (18 ) (19 ) (8 ) Total loan receivables (18 ) (19 ) (8 ) Derivatives and other: Derivative gains (losses) (174 ) (224 ) (109 ) Foreign currency gains (losses) (62 ) (10 ) (33 ) Total derivatives and other (236 ) (234 ) (142 ) Total realized investment gains (losses) $ (135 ) $ (430 ) $ (151 ) (1) Includes impairments of $22 in 2017 The unrealized holding gains , net of losses , recorded as a component of realized investment gains and losses for the year ended December 31, 2019 , that relates to equity securities still held at the December 31, 2019 , reporting date was $64 million . Unrealized Investment Gains and Losses Information regarding changes in unrealized gains and losses from investments recorded in AOCI for the years ended December 31 follows: (In millions) 2019 2018 2017 Changes in unrealized gains (losses): Fixed maturity securities, available for sale $ 5,852 $ (3,142 ) $ 1,657 Equity securities 0 0 71 Total change in unrealized gains (losses) $ 5,852 $ (3,142 ) $ 1,728 Effect on Shareholders' Equity The net effect on shareholders' equity of unrealized gains and losses from fixed maturity securities at December 31 was as follows: (In millions) 2019 2018 Unrealized gains (losses) on securities available for sale $ 11,891 $ 6,039 Deferred income taxes (3,343 ) (1,805 ) Shareholders’ equity, unrealized gains (losses) on fixed maturity securities $ 8,548 $ 4,234 Gross Unrealized Loss Aging The following tables show the fair values and gross unrealized losses of the Company's available-for-sale and held-to-maturity investments that were in an unrealized loss position, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at December 31 . 2019 Total Less than 12 months 12 months or longer (In millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturity securities: Municipalities: Yen-denominated $ 80 $ 3 $ 80 $ 3 $ 0 $ 0 Public utilities: U.S. dollar-denominated 306 10 69 2 237 8 Banks/financial institutions: U.S. dollar-denominated 79 4 18 0 61 4 Yen-denominated 1,828 89 1,828 89 0 0 Other corporate: U.S. dollar-denominated 4,261 248 792 53 3,469 195 Yen-denominated 636 31 636 31 0 0 Total $ 7,190 $ 385 $ 3,423 $ 178 $ 3,767 $ 207 2018 Total Less than 12 months 12 months or longer (In millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturity securities: U.S. government and U.S. dollar-denominated $ 67 $ 1 $ 67 $ 1 $ 0 $ 0 Japan government and Yen-denominated 3,604 140 3,604 140 0 0 Municipalities: U.S. dollar-denominated 515 8 515 8 0 0 Yen-denominated 148 9 148 9 0 0 Mortgage- and asset- U.S. dollar-denominated 74 1 74 1 0 0 Public utilities: U.S. dollar-denominated 1,585 105 892 48 693 57 Yen-denominated 604 12 604 12 0 0 Banks/financial institutions: U.S. dollar-denominated 625 35 340 19 285 16 Yen-denominated 3,057 258 3,057 258 0 0 Other corporate: U.S. dollar-denominated 12,899 1,109 5,782 407 7,117 702 Yen-denominated 1,306 82 1,306 82 0 0 Total $ 24,484 $ 1,760 $ 16,389 $ 985 $ 8,095 $ 775 Analysis of Securities in Unrealized Loss Positions The unrealized losses on the Company's fixed maturity securities investments have been primarily related to general market changes in interest rates, foreign exchange rates, and/or the levels of credit spreads rather than specific concerns with the issuer's ability to pay interest and repay principal. For any significant declines in fair value of its fixed maturity securities, the Company performs a more focused review of the related issuers' credit profile. For corporate issuers, the Company evaluates their assets, business profile including industry dynamics and competitive positioning, financial statements and other available financial data. For non-corporate issuers, the Company analyzes all sources of credit support, including issuer-specific factors. The Company utilizes information available in the public domain and, for certain private placement issuers, from consultations with the issuers directly. The Company also considers ratings from Nationally Recognized Statistical Rating Organizations (NRSROs), as well as the specific characteristics of the security it owns including seniority in the issuer's capital structure, covenant protections, or other relevant features. From these reviews, the Company evaluates the issuers' continued ability to service the Company's investment through payment of interest and principal. Assuming no credit-related factors develop, unrealized gains and losses on fixed maturity securities are expected to diminish as investments near maturity. Based on its credit analysis, the Company believes that the issuers of its fixed maturity investments in the sectors shown in the table above have the ability to service their obligations to the Company. Commercial Mortgage and Other Loans The Company classifies its TREs, CMLs and MMLs as held-for-investment and includes them in the commercial mortgage and other loans line on the consolidated balance sheets. The Company carries them on the balance sheet at amortized cost less an estimated allowance for loan losses. The table below reflects the composition of the carrying value for commercial mortgage and other loans by property type as of December 31. (In millions) 2019 2018 Amortized Cost % of Total Amortized Cost % of Total Commercial Mortgage and other loans Transitional real estate loans: Office $ 1,800 18.7 % $ 1,621 23.3 % Retail 131 1.4 147 2.1 Apartments/Multi-Family 2,085 21.7 1,706 24.6 Industrial 256 2.7 250 3.6 Hospitality 1,036 10.8 531 7.6 Other 164 1.7 139 2.0 Total transitional real estate loans 5,472 57.0 4,394 63.2 Commercial mortgage loans: Office 410 4.3 281 4.1 Retail 348 3.5 316 4.6 Apartments/Multi-Family 569 5.9 369 5.3 Industrial 383 4.0 99 1.4 Total commercial mortgage loans 1,710 17.7 1,065 15.4 Middle market loans 2,432 25.3 1,487 21.4 Total commercial mortgage and other loans $ 9,614 100.0 % $ 6,946 100.0 % Allowance for Loan Losses (45 ) (27 ) Total net commercial mortgage and other loans $ 9,569 $ 6,919 Commercial mortgage and transitional real estate loans were secured by properties entirely within the U.S. (with the largest concentrations in California ( 20% ), Texas ( 15% ) and Florida ( 10% )). Middle market loans are issued only to companies domiciled within the U.S. and Canada. Transitional Real Estate Loans Transitional real estate loans are commercial mortgage loans that are typically relatively short-term floating rate instruments secured by a first lien on the property.These loans provide funding for properties undergoing a change in their physical characteristics and/or economic profile and do not typically require any principal repayment prior to the maturity date. This loan portfolio is generally considered to be investment grade. As of December 31, 2019 , the Company had $875 million in outstanding commitments to fund transitional real estate loans. These commitments are contingent on the final underwriting and due diligence to be performed. Commercial Mortgage Loans Commercial mortgage loans are typically fixed rate loans on commercial real estate with partial repayment of principal over the life of the loan with the remaining outstanding principal being repaid upon maturity. This loan portfolio is generally considered higher quality investment grade loans. As of December 31, 2019 , the Company had $27 million of outstanding commitments to fund commercial mortgage loans. These commitments are contingent on the final underwriting and due diligence to be performed. Middle Market Loans Middle market loans are typically first lien senior secured cash flow loans to small to mid-size companies for working capital, refinancing, acquisition, and recapitalization. These loans are generally considered to be below investment grade. The carrying value for middle market loans included $99 million and $56 million for a short term credit facility that is reflected in other liabilities on the consolidated balance sheets, as of December 31, 2019 , and 2018 , respectively. As of December 31, 2019 , the Company had commitments of approximately $502 million to fund potential future loan originations related to this investment program. These commitments are contingent upon the availability of middle market loans that meet the Company's underwriting criteria. Allowance for Loan Losses The Company's allowance for loan losses is established using both general and specific allowances. The general allowance is used for loans grouped by similar risk characteristics where a loan-specific or market-specific risk has not been identified, but for which the Company estimates probable incurred losses. The specific allowance is used on an individual loan basis when it is probable that a loss has been incurred. As of December 31, 2019 , the Company had loan loss reserves of $6 million related to two specific middle market loans. There was no specific loan loss reserve as of December 31, 2018 . The following table presents the rollforward of the Company's allowance for loan losses by portfolio segment during the year ended December 31. (In millions) Commercial Mortgage Loans Transitional Real Estate Loans Middle Market Loans Total Allowance for loan losses at December 31, 2018 $ (1 ) $ (17 ) $ (9 ) $ (27 ) Addition to (release of) allowance for credit losses (2 ) (5 ) (11 ) (18 ) Allowance for loan losses at December 31, 2019 $ (3 ) $ (22 ) $ (20 ) $ (45 ) As of December 31, 2019 and 2018, the Company had no loans that were past due in regards to principal and/or interest payments. Additionally, the Company held no loans that were on nonaccrual status or considered impaired as of December 31, 2019 and 2018. The Company had no troubled debt restructurings during the years ended December 31, 2019 and 2018. Credit Quality Indicators The key credit quality indicators used by the Company in establishing the general and specific loan loss reserves, as well as in determining whether or not a loan should be impaired, include loan-to-value and debt service coverage ratios for CMLs and TREs and ratings for its middle market loan portfolio. Given that transitional real estate loans involve properties undergoing renovation or construction, loan-to-value provides the most insight on the credit risk of the property. Middle market loans generally have below-investment-grade ratings. The performance of the loans are monitored and reviewed periodically, but not less than quarterly. The table below summarizes key credit quality information by carrying value for CMLs and TREs as of December 31. 2019 (In millions) Transitional Real Estate Loans Commercial Mortgage Loans Total Loan-to-Value Ratio: 0%-59.99% $ 1,424 $ 1,390 $ 2,814 60%-69.99% 1,927 297 2,224 70%-79.99% 2,085 23 2,108 80% or greater 36 0 36 Total $ 5,472 $ 1,710 $ 7,182 Weighted Average Debt-Service Coverage Ratio 2.38 2018 (In millions) Transitional Real Estate Loans Commercial Mortgage Loans Total Loan-to-Value Ratio: 0%-59.99% $ 819 $ 877 $ 1,696 60%-69.99% 1,681 165 1,846 70%-79.99% 1,558 23 1,581 80% or greater 336 0 336 Total $ 4,394 $ 1,065 $ 5,459 Weighted Average Debt-Service Coverage Ratio 2.45 Other Investments The table below reflects the composition of the carrying value for other investments as of December 31. (In millions) 2019 2018 Other investments: Policy loans $ 250 $ 232 Short-term investments (1) 628 152 Limited partnerships 569 377 Other 30 26 Total other investments $ 1,477 $ 787 (1) Includes securities lending collateral As of December 31, 2019 , the Company had $1.3 billion in outstanding commitments to fund alternative investments in limited partnerships. Variable Interest Entities (VIEs) As a condition of its involvement or investment in a VIE, the Company enters into certain protective rights and covenants that preclude changes in the structure of the VIE that would alter the creditworthiness of the Company's investment or its beneficial interest in the VIE. For those VIEs other than certain unit trust structures, the Company's involvement is passive in nature. The Company has not, nor has it been, required to purchase any securities issued in the future by these VIEs. The Company's ownership interest in VIEs is limited to holding the obligations issued by them. The Company has no direct or contingent obligations to fund the limited activities of these VIEs, nor does it have any direct or indirect financial guarantees related to the limited activities of these VIEs. The Company has not provided any assistance or any other type of financing support to any of the VIEs it invests in, nor does it have any intention to do so in the future. For those VIEs in which the Company holds debt obligations, the weighted-average lives of the Company's notes are very similar to the underlying collateral held by these VIEs where applicable. The Company's risk of loss related to its interests in any of its VIEs is limited to the carrying value of the related investments held in the VIE. VIEs - Consolidated The following table presents the cost or amortized cost, fair value and balance sheet caption in which the assets and liabilities of consolidated VIEs are reported as of December 31. Investments in Consolidated Variable Interest Entities 2019 2018 (In millions) Cost or Amortized Fair Cost or Amortized Fair Assets: Fixed maturity securities, available for sale $ 3,308 $ 4,312 $ 3,849 $ 4,466 Equity securities 0 0 160 160 Commercial mortgage and other loans 7,956 8,015 5,528 5,506 Other investments (1) 494 494 328 328 Other assets (2) 169 169 182 182 Total assets of consolidated VIEs $ 11,927 $ 12,990 $ 10,047 $ 10,642 Liabilities: Other liabilities (2) $ 126 $ 126 $ 102 $ 102 Total liabilities of consolidated VIEs $ 126 $ 126 $ 102 $ 102 (1) Consists entirely of alternative investments in limited partnerships (2) Consists entirely of derivatives The Company is substantively the only investor in the consolidated VIEs listed in the table above. As the sole investor in these VIEs, the Company has the power to direct the activities of a variable interest entity that most significantly impact the entity's economic performance and is therefore considered to be the primary beneficiary of the VIEs that it consolidates. The Company also participates in substantially all of the variability created by these VIEs. The activities of these VIEs are limited to holding invested assets and foreign currency swaps, as appropriate, and utilizing the cash flows from these securities to service its investment. Neither the Company nor any of its creditors are able to obtain the underlying collateral of the VIEs unless there is an event of default or other specified event. For those VIEs that contain a swap, the Company is not a direct counterparty to the swap contracts and has no control over them. The Company's loss exposure to these VIEs is limited to its original investment. The Company's consolidated VIEs do not rely on outside or ongoing sources of funding to support their activities beyond the underlying collateral and swap contracts, if applicable. With the exception of its investment in unit trust structures, the underlying collateral assets and funding of the Company's consolidated VIEs are generally static in nature. Investments in Unit Trust Structures The Company also utilizes unit trust structures in its Aflac Japan segment to invest in various asset classes. As the sole investor of these VIEs, the Company is required to consolidate these trusts under U.S. GAAP. VIEs - Not Consolidated The table below reflects the amortized cost, fair value and balance sheet caption in which the Company's investment in VIEs not consolidated are reported as of December 31. Investments in Variable Interest Entities Not Consolidated 2019 2018 (In millions) Amortized Fair Amortized Fair Assets: Fixed maturity securities, available for sale $ 4,129 $ 4,884 $ 4,575 $ 4,982 Fixed maturity securities, held to maturity 1,848 2,236 2,007 2,254 Other investments (1) 75 74 49 49 Total investments in VIEs not consolidated $ 6,052 $ 7,194 $ 6,631 $ 7,285 (1) Consists entirely of alternative investments in limited partnerships The Company holds alternative investments in limited partnerships that have been determined to be VIEs. These partnerships invest in private equity and structured investments. The Company’s maximum exposure to loss on these investments is limited to the amount of its investment. The Company is not the primary beneficiary of these VIEs and is therefore not required to consolidate them. The Company classifies these investments as Other investments in the consolidated balance sheets. Securities Lending and Pledged Securities The Company lends fixed maturity and public equity securities to financial institutions in short-term security-lending transactions. These short-term security-lending arrangements increase investment income with minimal risk. The Company receives cash or other securities as collateral for such loans. The Company's security lending policy requires that the fair value of the securities received as collateral be 102% or more of the fair value of the loaned securities and that unrestricted cash received as collateral be 100% or more of the fair value of the loaned securities. The securities loaned continue to be carried as investment assets on the Company's balance sheet during the terms of the loans and are not reported as sales. For loans involving unrestricted cash or securities as collateral, the collateral is reported as an asset with a corresponding liability for the return of the collateral. For loans where the Company receives as collateral securities that the Company is not permitted to sell or repledge, the collateral is not reflected on the consolidated financial statements. Details of collateral by loaned security type and remaining maturity of the agreements as of December 31 were as follows: Securities Lending Transactions Accounted for as Secured Borrowings 2019 Remaining Contractual Maturity of the Agreements (In millions) Overnight (1) Up to 30 Greater Total Securities lending transactions: Fixed maturity securities: Japan government and agencies $ 0 $ 1,013 $ 4,759 $ 5,772 Public utilities 35 0 0 35 Sovereign and supranational 2 0 0 2 Banks/financial institutions 48 0 0 48 Other corporate 778 0 0 778 Equity securities 0 0 0 0 Total borrowings $ 863 $ 1,013 $ 4,759 $ 6,635 Gross amount of recognized liabilities for securities lending transactions $ 1,876 Amounts related to agreements not included in offsetting disclosure in Note 4 $ 4,759 (1) The related loaned security, under the Company's Aflac U.S. securities lending program, can be returned to the Company at the transferee's discretion; therefore, they are classified as Overnight and Continuous. Securities Lending Transactions Accounted for as Secured Borrowings 2018 Remaining Contractual Maturity of the Agreements (In millions) Overnight (1) Up to 30 Greater Total Securities lending transactions: Fixed maturity securities: Japan government and agencies $ 0 $ 387 1,190 $ 1,577 Municipalities 5 0 0 5 Public utilities 27 0 0 27 Banks/financial institutions 74 0 0 74 Other corporate 549 0 0 549 Equity securities 10 0 0 10 Total borrowings $ 665 $ 387 $ 1,190 $ 2,242 Gross amount of recognized liabilities for securities lending transactions $ 1,052 Amounts related to agreements not included in offsetting disclosure in Note 4 $ 1,190 (1) The related loaned security, under the Company's Aflac U.S. securities lending program, can be returned to the Company at the transferee's discretion; therefore, they are classified as Overnight and Continuous The Company did not have any repurchase agreements or repurchase-to-maturity transactions outstanding as of December 31, 2019 and 2018 , respectively. Certain fixed maturity securities can be pledged as collateral as part of derivative transactions, or pledged to support state deposit requirements on certain investment programs. For additional information regarding pledged securities related to derivative transactions, see Note 4. At December 31, 2019 , debt securities with a fair value of $18 million were on deposit with regulatory authorities in the U.S. (including U.S. territories). The Company retains ownership of all securities on deposit and receives the related investment income. For general information regarding the Company's investment accounting policies, see Note 1.

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	12 Months Ended
DERIVATIVE INSTRUMENTS	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS	DERIVATIVE INSTRUMENTS The Company's freestanding derivative financial instruments have historically consisted of: • foreign currency forwards and options used in hedging foreign exchange risk on U.S. dollar-denominated investments in Aflac Japan's portfolio • foreign currency forwards and options used to economically hedge certain portions of forecasted cash flows denominated in yen and hedge the Company's long term exposure to a weakening yen • cross-currency interest rate swaps, also referred to as foreign currency swaps, associated with certain senior notes and subordinated debentures • foreign currency swaps and, in prior periods, credit default swaps that are associated with investments in special-purpose entities, including VIEs where the Company is the primary beneficiary • interest rate swaps used to economically hedge interest rate fluctuations in certain variable-rate investments • interest rate swaptions used to hedge changes in the fair value associated with interest rate fluctuations for certain U.S. dollar-denominated available-for-sale fixed-maturity securities. Some of the Company's derivatives are designated as cash flow hedges, fair value hedges or net investment hedges; however, other derivatives do not qualify for hedge accounting or the Company elects not to designate them as accounting hedges. Derivative Types Foreign currency forwards and options are executed for the Aflac Japan segment in order to hedge the currency risk on the carrying value of certain U.S. dollar-denominated investments. The average maturity of these forwards and options can change depending on factors such as market conditions and types of investments being held. In situations where the maturity of the forwards and options is shorter than the underlying investment being hedged, the Company may enter into new forwards and options near maturity of the existing derivative in order to continue hedging the underlying investment. In forward transactions, Aflac Japan agrees with another party to buy a fixed amount of yen and sell a corresponding amount of U.S. dollars at a specified future date. Aflac Japan also executes foreign currency option transactions in a collar strategy, where Aflac Japan agrees with another party to simultaneously purchase put options and sell call options. In the purchased put transactions, Aflac Japan obtains the option to buy a fixed amount of yen and sell a corresponding amount of U.S. dollars at a specified future date. In the sold call transaction, Aflac Japan agrees to sell a fixed amount of yen and buy a corresponding amount of U.S. dollars at a specified future date. The combination of purchasing the put option and selling the call option results in no net premium being paid (i.e. a costless or zero-cost collar). The foreign currency forwards and options are used in fair value hedging relationships to mitigate the foreign exchange risk associated with U.S. dollar-denominated investments supporting yen-denominated liabilities. From time to time, the Company may also enter into foreign currency forwards and options to hedge the currency risk associated with the net investment in Aflac Japan. In these forward transactions, Aflac agrees with another party to buy a fixed amount of U.S. dollars and sell a corresponding amount of yen at a specified price at a specified future date. In the option transactions, the Company may use a combination of foreign currency options to protect expected future cash flows by simultaneously purchasing yen put options (options that protect against a weakening yen) and selling yen call options (options that limit participation in a strengthening yen). The combination of these two actions create a zero-cost collar. The Company enters into foreign currency swaps pursuant to which it exchanges an initial principal amount in one currency for an initial principal amount of another currency, with an agreement to re-exchange the principal amounts at a future date. There may also be periodic exchanges of payments at specified intervals based on the agreed upon rates and notional amounts. Foreign currency swaps are used primarily in the consolidated VIEs in the Company's Aflac Japan portfolio to convert foreign-denominated cash flows to yen, the functional currency of Aflac Japan, in order to minimize cash flow fluctuations. The Company also uses foreign currency swaps to economically convert certain of its U.S. dollar-denominated senior note and subordinated debenture principal and interest obligations into yen-denominated obligations. In order to reduce investment income volatility from its variable-rate investments, the Company enters into receive–fixed, pay–floating interest rate swaps. These derivatives are cleared and settled through a central clearinghouse. Swaptions are used to mitigate the adverse impact resulting from significant changes in the fair value of U.S. dollar-denominated available-for-sale securities due to fluctuation in interest rates. In a payer swaption, the Company pays a premium to obtain the right, but not the obligation, to enter into a swap contract where it will pay a fixed rate and receive a floating rate. Interest rate swaption collars are combinations of two swaption positions. In order to maximize the efficiency of the collars while minimizing cost, a collar strategy is used whereby the Company purchases a long payer swaption (the Company purchases an option that allows it to enter into a swap where the Company will pay the fixed rate and receive the floating rate of the swap) and sells a short receiver swaption (the Company sells an option that provides the counterparty with the right to enter into a swap where the Company will receive the fixed rate and pay the floating rate of the swap). The combination of purchasing the long payer swaption and selling the short receiver swaption results in no net premium being paid (i.e. a costless or zero-cost collar). Derivative Balance Sheet Classification The table below summarizes the balance sheet classification of the Company's derivative fair value amounts, as well as the gross asset and liability fair value amounts, at December 31. The fair value amounts presented do not include income accruals. Derivative assets are included in “Other Assets,” while derivative liabilities are included in “Other Liabilities” within the Company’s Consolidated Balance Sheets. The notional amount of derivative contracts represents the basis upon which pay or receive amounts are calculated and are not reflective of exposure or credit risk. 2019 2018 (In millions) Asset Liability Asset Liability Hedge Designation/ Derivative Notional Fair Value Fair Value Notional Fair Value Fair Value Cash flow hedges: Foreign currency swaps - VIE $ 75 $ 0 $ 8 $ 75 $ 1 $ 4 Total cash flow hedges 75 0 8 75 1 4 Fair value hedges: Foreign currency forwards 964 0 38 2,086 0 34 Foreign currency options 11,573 0 5 9,070 3 1 Interest rate swaptions 243 0 0 500 0 1 Total fair value hedges 12,780 0 43 11,656 3 36 Net investment hedge: Foreign currency forwards 4,952 72 2 0 0 0 Foreign currency options 2,000 0 0 0 0 0 Total net investment hedge 6,952 72 2 0 0 0 Non-qualifying strategies: Foreign currency swaps 2,800 72 78 2,800 103 129 Foreign currency swaps - VIE 2,587 169 118 2,587 181 101 Foreign currency forwards 19,821 166 337 16,057 126 117 Foreign currency options 9,553 0 0 430 0 0 Interest rate swaps 7,120 3 0 4,750 3 0 Interest rate swaptions 7 0 0 0 0 0 Total non-qualifying strategies 41,888 410 533 26,624 413 347 Total derivatives $ 61,695 $ 482 $ 586 $ 38,355 $ 417 $ 387 Cash Flow Hedges For certain variable-rate U.S. dollar-denominated available-for-sale securities held by Aflac Japan via consolidated VIEs, foreign currency swaps are used to swap the USD variable rate interest and principal payments to fixed rate JPY interest and principal payments. The Company has designated foreign currency swaps as a hedge of the variability in cash flows of a forecasted transaction or of amounts to be received or paid related to a recognized asset (“cash flow” hedge). The remaining maximum length of time for which these cash flows are hedged is seven years. The derivatives in the Company's consolidated VIEs that are not designated as accounting hedges are discussed in the "non-qualifying strategies" section of this note. Fair Value Hedges The Company designates and accounts for certain foreign currency forwards, options, and interest rate swaptions as fair value hedges when they meet the requirements for hedge accounting. The Company recognizes gains and losses on these derivatives as well as the offsetting gain or loss on the related hedged items in current earnings. Foreign currency forwards and options hedge the foreign currency exposure of certain U.S. dollar-denominated available-for-sale fixed-maturity investments held in Aflac Japan. The change in the fair value of the foreign currency forwards related to the changes in the difference between the spot rate and the forward price is excluded from the assessment of hedge effectiveness. The change in fair value of the foreign currency option related to the time value of the option is recognized in current earnings and is excluded from the assessment of hedge effectiveness. Interest rate swaptions hedge the interest rate exposure of certain U.S. dollar-denominated available-for-sale securities held in Aflac Japan. For these hedging relationships, the Company excludes time value from the assessment of hedge effectiveness and recognizes changes in the intrinsic value of the swaptions in current earnings within net investment income. The change in the time value of the swaptions is recognized in other comprehensive income (loss) and amortized into earnings (net investment income) over its legal term. The following table presents the gains and losses on derivatives and the related hedged items in fair value hedges for the years ended December 31. Fair Value Hedging Relationships (In millions) Hedging Derivatives Hedged Items Hedging Derivatives Hedged Items Total Gains (Losses) (1) Gains (Losses) (2) Gains (Losses) (2) Net Realized Gains (Losses) Recognized for Fair Value Hedge 2019: Foreign currency Fixed maturity securities $ (50 ) $ (64 ) $ 14 $ (12 ) $ 2 Foreign currency Fixed maturity securities (7 ) (7 ) 0 0 0 Interest rate Fixed maturity securities (9 ) (9 ) 0 0 0 Total gains (losses) $ (66 ) $ (80 ) $ 14 $ (12 ) $ 2 2018: Foreign currency forwards Fixed maturity securities $ 126 $ (104 ) $ 230 $ (242 ) $ (12 ) Foreign currency options Fixed maturity securities 4 4 0 0 0 Interest rate Fixed maturity securities (1 ) (1 ) 0 0 0 Total gains (losses) $ 129 $ (101 ) $ 230 $ (242 ) $ (12 ) 2017: Foreign currency forwards Fixed maturity and equity securities $ 98 $ (202 ) $ 300 $ (278 ) $ 22 Foreign currency options Fixed maturity securities 21 10 11 (10 ) 1 Total gains (losses) $ 119 $ (192 ) $ 311 $ (288 ) $ 23 (1) Gains (losses) excluded from effectiveness testing includes the forward point on foreign currency forwards and time value change on foreign currency options which are reported in the consolidated statement of earnings as realized investment gains (losses). It also includes the change in the fair value of the interest rate swaptions related to the time value of the swaptions which is recognized as a component of other comprehensive income (loss). (2) Gains and losses on foreign currency forwards and options and related hedged items are reported in the consolidated statement of earnings as realized investment gains (losses). For interest rate swaptions and related hedged items, gains and losses included in the hedge assessment, premium amortization and time value amortization while the hedge items are still outstanding are reported within net investment income. The time value gains and losses for interest rate swaptions when the related hedged items are redeemed are reported in realized investment gains and losses consistent with the impact of the hedged item. For the years ended December 31, 2019 and 2018, gains and losses included in the hedge assessment on interest rate swaptions and related hedged items were immaterial. The following table shows the carrying amounts of assets designated and qualifying as hedged items in fair value hedges of interest rate risk and the related cumulative hedge adjustment included in the carrying amount as of December 31. (In millions) Carrying Amount of the Hedged Assets/(Liabilities) (1) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Assets/(Liabilities) 2019 2018 2019 2018 Fixed maturity securities $ 4,633 $ 6,593 $ 256 $ 294 (1) The balance includes hedging adjustment on discontinued hedging relationships of $256 in 2019 and $294 in 2018 . The total notional amount of the Company's interest rate swaptions was $243 in 2019 and $500 in 2018 . The hedging adjustment related to these derivatives was immaterial. Net Investment Hedge The Company's investment in Aflac Japan is affected by changes in the yen/dollar exchange rate. To mitigate this exposure, the Parent Company's yen-denominated liabilities (see Note 9) have been designated as non-derivative hedges. Beginning in July 2019, certain foreign currency forwards and options were designated as derivative hedges of the foreign currency exposure of the Company's net investment in Aflac Japan. Prior to April 1, 2018, foreign currency forwards and options were also designated as derivative hedges of the foreign currency exposure of the Company's net investment in Aflac Japan. The Company's net investment hedge was effective during the years ended December 31, 2019 , 2018 and 2017 . Non-qualifying Strategies For the Company's derivative instruments in consolidated VIEs that do not qualify for hedge accounting treatment, all changes in their fair value are reported in current period earnings within realized investment gains (losses). The amount of gain or loss recognized in earnings for the Company's VIEs is attributable to the derivatives in those investment structures. While the change in value of the swaps is recorded through current period earnings, the change in value of the available-for-sale fixed maturity securities associated with these swaps is recorded through other comprehensive income. As of December 31, 2019 , the Parent Company had cross-currency interest rate swap agreements related to its $350 million senior notes due February 2022, $700 million senior notes due June 2023, $750 million senior notes due November 2024 and $450 million senior notes due March 2025. Changes in the values of these swaps are recorded through current period earnings. For additional information regarding these swaps, see Note 9. The Company uses foreign exchange forwards and options to economically mitigate the currency risk of some of its U.S. dollar-denominated loan receivables held within the Aflac Japan segment. These arrangements are not designated as accounting hedges, as the foreign currency remeasurement of the loan receivables impacts current period earnings, and generally offsets gains and losses from foreign exchange forwards within realized investment gains (losses). The Company also has certain foreign exchange forwards on U.S. dollar-denominated AFS securities where hedge accounting is not being applied. Prior to July 2019, in order to economically mitigate currency risk of future yen dividends from Aflac Japan while lowering consolidated hedge costs associated with Aflac Japan's U.S. dollar investment hedging, the Parent Company entered into offsetting hedge positions using foreign exchange forwards. This activity is reported in the Corporate and other segment. As of July 1, 2019, the Parent Company designates these foreign exchange forward contracts as accounting hedges of its net investment in Aflac Japan. The Company uses interest rate swaps to economically convert the variable rate investment income to a fixed rate on certain variable-rate investments. Impact of Derivatives and Hedging Instruments The following table summarizes the impact to realized investment gains (losses) and other comprehensive income (loss) from all derivatives and hedging instruments for the years ended December 31. 2019 2018 2017 (In millions) Net Investment Income (1) Realized Investment Other (2) Net Investment Income (1) Realized Investment Other (2) Net Investment Income (1) Realized Other (2) Qualifying hedges: Cash flow hedges: Foreign currency swaps - VIE $ (2 ) $ (1 ) $ (4 ) $ 0 $ 0 $ 3 $ 0 $ 0 $ 1 Total cash flow hedges (2 ) (1 ) (3) (4 ) 0 0 (3) 3 0 0 (3) 1 Fair value hedges: Foreign currency forwards (3) (62 ) (116 ) (180 ) Foreign currency options (3) (7 ) 4 11 Interest rate swaptions (3) (1 ) 0 (8 ) 0 0 (1 ) 0 0 0 Total fair value hedges (1 ) (69 ) (8 ) 0 (112 ) (1 ) 0 (169 ) 0 Net investment hedge: Non-derivative hedging 0 (24 ) 0 (32 ) 0 (15 ) Foreign currency forwards 10 83 0 0 0 (25 ) Foreign currency options (4 ) 0 0 (8 ) 0 5 Total net investment hedge 6 59 0 (40 ) 0 (35 ) Non-qualifying strategies: Foreign currency swaps 90 (40 ) 9 Foreign currency swaps - VIE (68 ) 60 44 Foreign currency forwards (148 ) (135 ) 8 Credit default swaps 0 0 (1 ) Interest rate swaps 17 3 0 Total non-qualifying strategies (110 ) (112 ) 60 Total $ (3 ) $ (174 ) $ 47 $ 0 $ (224 ) $ (38 ) $ 0 $ (109 ) $ (34 ) (1) Cash flow hedge items and the change in the fair value of interest rate swaptions related to the time value of the swaptions in fair value hedges are recorded as unrealized gains (losses) on derivatives and net investment hedge items are recorded in the unrealized foreign currency translation gains (losses) line in the consolidated statement of comprehensive income (loss). (2) Impact of cash flow hedges reported as realized investment gains (losses) includes an immaterial amount of gains or losses reclassified from accumulated other comprehensive income (loss) into earnings. It also includes an immaterial amount excluded from effectiveness testing during the years ended December 31, 2019 , 2018 and 2017 , respectively. (3) Impact shown net of effect of hedged items (see Fair Value Hedges section of this Note 4 for further detail) As of December 31, 2019 , deferred gains and losses on derivative instruments recorded in accumulated other comprehensive income that are expected to be reclassified to earnings during the next twelve months were immaterial. Credit Risk Assumed through Derivatives For the foreign currency and credit default swaps associated with the Company's VIE investments for which it is the primary beneficiary, the Company bears the risk of loss due to counterparty default even though it is not a direct counterparty to those contracts. The Company is a direct counterparty to the foreign currency swaps that it has entered into in connection with certain of its senior notes and subordinated debentures; foreign currency forwards; and foreign currency options, and therefore the Company is exposed to credit risk in the event of nonperformance by the counterparties in those contracts. The risk of counterparty default for the Company's foreign currency swaps, certain foreign currency forwards, and foreign currency options is mitigated by collateral posting requirements that counterparties to those transactions must meet. As of December 31, 2019 , all of the Company's derivative agreement counterparties were investment grade. The Company engages in over-the-counter (OTC) bilateral derivative transactions directly with unaffiliated third parties under International Swaps and Derivatives Association, Inc. (ISDA) agreements and other documentation. Most of the ISDA agreements also include Credit Support Annexes (CSAs) provisions, which generally provide for two-way collateral postings at the first dollar of exposure. The Company mitigates the risk that counterparties to transactions might be unable to fulfill their contractual obligations by monitoring counterparty credit exposure and collateral value while generally requiring that collateral be posted at the outset of the transaction. In addition, a significant portion of the derivative transactions have provisions that give the counterparty the right to terminate the transaction upon a downgrade of Aflac’s financial strength rating. The actual amount of payments that the Company could be required to make depends on market conditions, the fair value of outstanding affected transactions, and other factors prevailing at and after the time of the downgrade. The Company also engages in OTC cleared derivative transactions through regulated central clearing counterparties. These positions are marked to market and margined on a daily basis (both initial margin and variation margin), and the Company has minimal exposure to credit-related losses in the event of nonperformance by counterparties to these derivatives. Collateral posted by the Company to third parties for derivative transactions can generally be repledged or resold by the counterparties. The aggregate fair value of all derivative instruments with credit-risk-related contingent features that were in a net liability position by counterparty was approximately $301 million and $139 million as of December 31, 2019 and 2018 , respectively. If the credit-risk-related contingent features underlying these agreements had been triggered on December 31, 2019 , the Company estimates that it would be required to post a maximum of $46 million of additional collateral to these derivative counterparties. The Company is generally allowed to sell or repledge collateral obtained from its derivative counterparties, although it does not typically exercise such rights. (See the Offsetting tables below for collateral posted or received as of the reported balance sheet dates.) Offsetting of Financial Instruments and Derivatives Most of the Company's derivative instruments are subject to enforceable master netting arrangements that provide for the net settlement of all derivative contracts between the Parent Company or its subsidiaries and the respective counterparty in the event of default or upon the occurrence of certain termination events. Collateral support agreements with the master netting arrangements generally provide that the Company will receive or pledge financial collateral at the first dollar of exposure. The Company has securities lending agreements with unaffiliated financial institutions that post collateral to the Company in return for the use of its fixed maturity and public equity securities (see Note 3). When the Company has entered into securities lending agreements with the same counterparty, the agreements generally provide for net settlement in the event of default by the counterparty. This right of set-off allows the Company to keep and apply collateral received if the counterparty failed to return the securities borrowed from the Company as contractually agreed. For additional information on the Company's accounting policy for securities lending, see Note 1. The tables below summarize the Company's derivatives and securities lending transactions as of December 31, and as reflected in the tables, in accordance with U.S. GAAP, the Company's policy is to not offset these financial instruments in the Consolidated Balance Sheets. Offsetting of Financial Assets and Derivative Assets 2019 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Assets Gross Amount Offset in Balance Sheet Net Amount of Assets Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Received Net Amount Derivative assets: Derivative assets subject to a master netting agreement or offsetting arrangement OTC - bilateral $ 310 $ 0 $ 310 $ (190 ) $ (7 ) $ (113 ) $ 0 OTC - cleared 3 0 3 0 0 0 3 Total derivative 313 0 313 (190 ) (7 ) (113 ) 3 Derivative assets not subject to a master netting agreement or offsetting arrangement OTC - bilateral 169 169 169 Total derivative 169 169 169 Total derivative assets 482 0 482 (190 ) (7 ) (113 ) 172 Securities lending and similar arrangements 1,860 0 1,860 0 0 (1,860 ) 0 Total $ 2,342 $ 0 $ 2,342 $ (190 ) $ (7 ) $ (1,973 ) $ 172 2018 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Assets Gross Amount Offset in Balance Sheet Net Amount of Assets Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Received Net Amount Derivative assets: Derivative assets subject to a master netting agreement or offsetting arrangement OTC - bilateral $ 231 $ 0 $ 231 $ (152 ) $ (23 ) $ (55 ) $ 1 OTC - cleared 3 0 3 0 0 (3 ) 0 Total derivative 234 0 234 (152 ) (23 ) (58 ) 1 Derivative assets not subject to a master netting agreement or offsetting arrangement OTC - bilateral 183 183 183 Total derivative 183 183 183 Total derivative assets 417 0 417 (152 ) (23 ) (58 ) 184 Securities lending and similar arrangements 1,029 0 1,029 0 0 (1,029 ) 0 Total $ 1,446 $ 0 $ 1,446 $ (152 ) $ (23 ) $ (1,087 ) $ 184 Offsetting of Financial Liabilities and Derivative Liabilities 2019 Gross Amounts Not Offset in Balance Sheet (In millions) Gross Amount of Recognized Liabilities Gross Amount Offset in Balance Sheet Net Amount of Liabilities Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Pledged Net Amount Derivative liabilities: Derivative liabilities subject to a master netting agreement or offsetting arrangement OTC - bilateral $ 459 $ 0 $ 459 $ (190 ) $ (222 ) $ (32 ) $ 15 OTC - cleared 1 0 1 0 0 (1 ) 0 Total derivative 460 0 460 (190 ) (222 ) (33 ) 15 Derivative liabilities not subject to a master netting agreement or offsetting arrangement OTC - bilateral 126 126 126 Total derivative 126 126 126 Total derivative liabilities 586 0 586 (190 ) (222 ) (33 ) 141 Securities lending and similar arrangements 1,876 0 1,876 (1,860 ) 0 0 16 Total $ 2,462 $ 0 $ 2,462 $ (2,050 ) $ (222 ) $ (33 ) $ 157 2018 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Liabilities Gross Amount Offset in Balance Sheet Net Amount of Liabilities Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Pledged Net Amount Derivative liabilities: Derivative liabilities subject to a master netting agreement or offsetting arrangement OTC - bilateral $ 285 $ 0 $ 285 $ (152 ) $ (37 ) $ (68 ) $ 28 Total derivative 285 0 285 (152 ) (37 ) (68 ) 28 Derivative liabilities not subject to a master netting agreement or offsetting arrangement OTC - bilateral 102 102 102 Total derivative 102 102 102 Total derivative liabilities 387 0 387 (152 ) (37 ) (68 ) 130 Securities lending and similar arrangements 1,052 0 1,052 (1,029 ) 0 0 23 Total $ 1,439 $ 0 $ 1,439 $ (1,181 ) $ (37 ) $ (68 ) $ 153 For additional information on the Company's financial instruments, see the accompanying Notes 1, 3 and 5.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
FAIR VALUE MEASUREMENTS	Dec. 31, 2019
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Fair Value Hierarchy U.S. GAAP specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. These two types of inputs create three valuation hierarchy levels. Level 1 valuations reflect quoted market prices for identical assets or liabilities in active markets. Level 2 valuations reflect quoted market prices for similar assets or liabilities in an active market, quoted market prices for identical or similar assets or liabilities in non-active markets or model-derived valuations in which all significant valuation inputs are observable in active markets. Level 3 valuations reflect valuations in which one or more of the significant inputs are not observable in an active market. The following tables present the fair value hierarchy levels of the Company's assets and liabilities that are measured and carried at fair value on a recurring basis as of December 31. 2019 (In millions) Quoted Prices in Significant Significant Total Assets: Securities available for sale, carried at Fixed maturity securities: Government and agencies $ 34,878 $ 1,522 $ 0 $ 36,400 Municipalities 0 1,847 0 1,847 Mortgage- and asset-backed securities 0 232 178 410 Public utilities 0 6,556 224 6,780 Sovereign and supranational 0 1,042 0 1,042 Banks/financial institutions 0 10,264 23 10,287 Other corporate 0 34,234 262 34,496 Total fixed maturity securities 34,878 55,697 687 91,262 Equity securities 642 80 80 802 Other investments 628 0 0 628 Cash and cash equivalents 4,896 0 0 4,896 Other assets: Foreign currency swaps 0 72 169 241 Foreign currency forwards 0 238 0 238 Interest rate swaps 0 3 0 3 Total other assets 0 313 169 482 Total assets $ 41,044 $ 56,090 $ 936 $ 98,070 Liabilities: Other liabilities: Foreign currency swaps $ 0 $ 78 $ 126 $ 204 Foreign currency forwards 0 377 0 377 Foreign currency options 0 5 0 5 Total liabilities $ 0 $ 460 $ 126 $ 586 2018 (In millions) Quoted Prices in Significant Significant Total Assets: Securities available for sale, carried at Fixed maturity securities: Government and agencies $ 32,993 $ 1,349 $ 0 $ 34,342 Municipalities 0 1,863 0 1,863 Mortgage- and asset-backed securities 0 162 177 339 Public utilities 0 7,062 109 7,171 Sovereign and supranational 0 1,260 0 1,260 Banks/financial institutions 0 8,895 23 8,918 Other corporate 0 28,789 213 29,002 Total fixed maturity securities 32,993 49,380 522 82,895 Equity securities 874 67 46 987 Other investments 152 0 0 152 Cash and cash equivalents 4,337 0 0 4,337 Other assets: Foreign currency swaps 0 103 182 285 Foreign currency forwards 0 126 0 126 Foreign currency options 0 3 0 3 Interest rate swaps 0 3 0 3 Total other assets 0 235 182 417 Total assets $ 38,356 $ 49,682 $ 750 $ 88,788 Liabilities: Other liabilities: Foreign currency swaps $ 0 $ 132 $ 102 $ 234 Foreign currency forwards 0 151 0 151 Foreign currency options 0 1 0 1 Interest rate swaptions 0 1 0 1 Total liabilities $ 0 $ 285 $ 102 $ 387 The following tables present the carrying amount and fair value categorized by fair value hierarchy level for the Company's financial instruments that are not carried at fair value as of December 31. 2019 (In millions) Carrying Quoted Prices in Significant Significant Total Assets: Securities held to maturity, Fixed maturity securities: Government and agencies $ 22,241 $ 27,937 $ 354 $ 0 $ 28,291 Municipalities 821 0 1,083 0 1,083 Mortgage and asset-backed 16 0 7 10 17 Public utilities 2,535 0 2,954 0 2,954 Sovereign and 1,123 0 1,320 0 1,320 Banks/financial institutions 916 0 1,018 0 1,018 Other corporate 2,433 0 2,911 0 2,911 Commercial mortgage and 9,569 0 0 9,648 9,648 Other investments (1) 30 0 30 0 30 Total assets $ 39,684 $ 27,937 $ 9,677 $ 9,658 $ 47,272 Liabilities: Other policyholders’ funds $ 7,317 $ 0 $ 0 $ 7,234 $ 7,234 Notes payable 6,408 0 6,663 272 6,935 Total liabilities $ 13,725 $ 0 $ 6,663 $ 7,506 $ 14,169 (1) Excludes policy loans of $250 and equity method investments of $569 , at carrying value 2018 (In millions) Carrying Quoted Prices in Significant Significant Total Assets: Securities held to maturity, Fixed maturity securities: Government and agencies $ 21,712 $ 27,030 $ 8 $ 0 $ 27,038 Municipalities 359 0 469 0 469 Mortgage and asset-backed 14 0 0 15 15 Public utilities 2,727 0 2,973 0 2,973 Sovereign and 1,551 0 1,840 0 1,840 Banks/financial institutions 1,445 0 1,583 0 1,583 Other corporate 2,510 0 2,804 0 2,804 Commercial mortgage and 6,919 0 0 6,893 6,893 Other investments (1) 26 0 26 0 26 Total assets $ 37,263 $ 27,030 $ 9,703 $ 6,908 $ 43,641 Liabilities: Other policyholders’ funds $ 7,146 $ 0 $ 0 $ 7,067 $ 7,067 Notes payable 5,765 0 5,606 270 5,876 Total liabilities $ 12,911 $ 0 $ 5,606 $ 7,337 $ 12,943 (1) Excludes policy loans of $232 and equity method investments of $377 , at carrying value Fair Value of Financial Instruments Fixed maturity and equity securities The Company determines the fair values of fixed maturity securities and public and privately-issued equity securities using the following approaches or techniques: price quotes and valuations from third party pricing vendors (including quoted market prices readily available from public exchange markets) and non-binding price quotes the Company obtains from outside brokers. A third party pricing vendor has developed valuation models to determine fair values of privately issued securities to reflect the impact of the persistent economic environment and the changing regulatory framework. These models are discounted cash flow (DCF) valuation models, but also use information from related markets, specifically the CDS market to estimate expected cash flows. These models take into consideration any unique characteristics of the securities and make various adjustments to arrive at an appropriate issuer-specific loss adjusted credit curve. This credit curve is then used with the relevant recovery rates to estimate expected cash flows and modeling of additional features, including illiquidity adjustments, if necessary, to price the security by discounting those loss adjusted cash flows. In cases where a credit curve cannot be developed from the specific security features, the valuation methodology takes into consideration other market observable inputs, including: 1) the most appropriate comparable security(ies) of the issuer 2) issuer-specific CDS spreads 3) bonds or CDS spreads of comparable issuers with similar characteristics such as rating, geography, or sector 4) bond indices that are comparative in rating, industry, maturity and region. The pricing data and market quotes the Company obtains from outside sources, including third party pricing services, are reviewed internally for reasonableness. If a fair value appears unreasonable, the Company will re-examine the inputs and assess the reasonableness of the pricing data with the vendor. Additionally, the Company may compare the inputs to relevant market indices and other performance measurements. Based on management's analysis, the valuation is confirmed or may be revised if there is evidence of a more appropriate estimate of fair value based on available market data. The Company has performed verification of the inputs and calculations in any valuation models to confirm that the valuations represent reasonable estimates of fair value. The fixed maturity securities classified as Level 3 consist of securities with limited or no observable valuation inputs. For Level 3 securities, the Company estimates the fair value of these securities by obtaining non-binding broker quotes from a limited number of brokers. These brokers base their quotes on a combination of their knowledge of the current pricing environment and market conditions. The Company considers these inputs to be unobservable. The Company also considers a variety of significant valuation inputs in the valuation process, including forward exchange rates, yen swap rates, dollar swap rates, interest rate volatilities, credit spread data on specific issuers, assumed default and default recovery rates, and certain probability assumptions. In obtaining these valuation inputs, the Company has determined that certain pricing assumptions and data used by its pricing sources are difficult to validate or corroborate by the market and/or appear to be internally developed rather than observed in or corroborated by the market. The use of these unobservable valuation inputs causes more subjectivity in the valuation process for these securities. For the periods presented, the Company has not adjusted the quotes or prices it obtains from the pricing services and brokers it uses. The following tables present the pricing sources for the fair values of the Company's fixed maturity and equity securities as of December 31. 2019 (In millions) Quoted Prices in Active Markets for Identical Assets Significant Observable Inputs Significant Unobservable Inputs Total Securities available for sale, carried at fair value: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 34,878 $ 1,522 $ 0 $ 36,400 Total government and agencies 34,878 1,522 0 36,400 Municipalities: Third party pricing vendor 0 1,847 0 1,847 Total municipalities 0 1,847 0 1,847 Mortgage- and asset-backed securities: Third party pricing vendor 0 232 0 232 Broker/other 0 0 178 178 Total mortgage- and asset-backed securities 0 232 178 410 Public utilities: Third party pricing vendor 0 6,556 0 6,556 Broker/other 0 0 224 224 Total public utilities 0 6,556 224 6,780 Sovereign and supranational: Third party pricing vendor 0 1,042 0 1,042 Total sovereign and supranational 0 1,042 0 1,042 Banks/financial institutions: Third party pricing vendor 0 10,264 0 10,264 Broker/other 0 0 23 23 Total banks/financial institutions 0 10,264 23 10,287 Other corporate: Third party pricing vendor 0 34,234 0 34,234 Broker/other 0 0 262 262 Total other corporate 0 34,234 262 34,496 Total securities available for sale $ 34,878 $ 55,697 $ 687 $ 91,262 Equity securities, carried at fair value: Third party pricing vendor $ 642 $ 80 $ 0 $ 722 Broker/other 0 0 80 80 Total equity securities $ 642 $ 80 $ 80 $ 802 2019 (In millions) Quoted Prices in Active Markets for Identical Assets Significant Observable Inputs Significant Unobservable Inputs Total Securities held to maturity, carried at amortized cost: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 27,937 $ 354 $ 0 $ 28,291 Total government and agencies 27,937 354 0 28,291 Municipalities: Third party pricing vendor 0 1,083 0 1,083 Total municipalities 0 1,083 0 1,083 Mortgage- and asset-backed securities: Third party pricing vendor 0 7 0 7 Broker/other 0 0 10 10 Total mortgage- and asset-backed securities 0 7 10 17 Public utilities: Third party pricing vendor 0 2,954 0 2,954 Total public utilities 0 2,954 0 2,954 Sovereign and supranational: Third party pricing vendor 0 1,320 0 1,320 Total sovereign and supranational 0 1,320 0 1,320 Banks/financial institutions: Third party pricing vendor 0 1,018 0 1,018 Total banks/financial institutions 0 1,018 0 1,018 Other corporate: Third party pricing vendor 0 2,911 0 2,911 Total other corporate 0 2,911 0 2,911 Total securities held to maturity $ 27,937 $ 9,647 $ 10 $ 37,594 2018 (In millions) Quoted Prices in Active Markets Significant Observable Significant Unobservable Inputs Total Securities available for sale, carried at fair value: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 32,993 $ 1,349 $ 0 $ 34,342 Total government and agencies 32,993 1,349 0 34,342 Municipalities: Third party pricing vendor 0 1,863 0 1,863 Total municipalities 0 1,863 0 1,863 Mortgage- and asset-backed securities: Third party pricing vendor 0 162 0 162 Broker/other 0 0 177 177 Total mortgage- and asset-backed securities 0 162 177 339 Public utilities: Third party pricing vendor 0 7,062 0 7,062 Broker/other 0 0 109 109 Total public utilities 0 7,062 109 7,171 Sovereign and supranational: Third party pricing vendor 0 1,260 0 1,260 Total sovereign and supranational 0 1,260 0 1,260 Banks/financial institutions: Third party pricing vendor 0 8,895 0 8,895 Broker/other 0 0 23 23 Total banks/financial institutions 0 8,895 23 8,918 Other corporate: Third party pricing vendor 0 28,789 0 28,789 Broker/other 0 0 213 213 Total other corporate 0 28,789 213 29,002 Total securities available for sale $ 32,993 $ 49,380 $ 522 $ 82,895 Equity securities, carried at fair value: Third party pricing vendor $ 874 $ 67 $ 0 $ 941 Broker/other 0 0 46 46 Total equity securities $ 874 $ 67 $ 46 $ 987 2018 (In millions) Quoted Prices in Active Markets Significant Observable Significant Unobservable Inputs Total Securities held to maturity, carried at amortized cost: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 27,030 $ 8 $ 0 $ 27,038 Total government and agencies 27,030 8 0 27,038 Municipalities: Third party pricing vendor 0 469 0 469 Total municipalities 0 469 0 469 Mortgage- and asset-backed securities: Broker/other 0 0 15 15 Total mortgage- and asset-backed securities 0 0 15 15 Public utilities: Third party pricing vendor 0 2,973 0 2,973 Total public utilities 0 2,973 0 2,973 Sovereign and supranational: Third party pricing vendor 0 1,840 0 1,840 Total sovereign and supranational 0 1,840 0 1,840 Banks/financial institutions: Third party pricing vendor 0 1,583 0 1,583 Total banks/financial institutions 0 1,583 0 1,583 Other corporate: Third party pricing vendor 0 2,804 0 2,804 Total other corporate 0 2,804 0 2,804 Total securities held to maturity $ 27,030 $ 9,677 $ 15 $ 36,722 The following is a discussion of the determination of fair value of the Company's remaining financial instruments. Derivatives The Company uses derivative instruments to manage the risk associated with certain assets. However, the derivative instrument may not be classified in the same fair value hierarchy level as the associated asset. The Company uses pricing models to determine the estimated fair value of derivatives. Inputs used to value derivatives include, but are not limited to, interest rates, credit spreads, foreign currency forward and spot rates, and interest volatility. The significant inputs to pricing derivatives are generally observable in the market or can be derived by observable market data. When these inputs are observable, the derivatives are classified as Level 2. The fair values of the foreign currency forwards and options are based on observable market inputs, therefore they are classified as Level 2. To determine the fair value of its interest rate derivatives, the Company uses inputs that are generally observable in the market or can be derived from observable market data. Interest rate swaps are cleared trades. In a cleared swap contract the clearinghouse provides benefits to the counterparties similar to contracts listed for investment traded on an exchange since it maintains a daily margin to mitigate counterparties credit risk. These derivatives are priced using observable inputs, accordingly, they are classified as Level 2. For its interest rate swaptions, the Company estimates their fair values using observable market data, including interest rate curves and volatilities. Their fair values are also classified as Level 2. For derivatives associated with VIEs where the Company is the primary beneficiary, the Company is not the direct counterparty to the swap contracts. As a result, the fair value measurements incorporate the credit risk of the collateral associated with the VIE. The Company receives valuations from a third party pricing vendor for these derivatives. Based on an analysis of these derivatives and a review of the methodology employed by the pricing vendor, the Company determined that due to the long duration of these swaps and the need to extrapolate from short-term observable data to derive and measure long-term inputs, certain inputs, assumptions and judgments are required to value future cash flows that cannot be corroborated by current inputs or current observable market data. As a result, the derivatives associated with the Company's consolidated VIEs are classified as Level 3 of the fair value hierarchy. Commercial mortgage and other loans Commercial mortgage and other loans include transitional real estate loans, commercial mortgage loans and middle market loans. The Company's loan receivables do not have readily determinable market prices and generally lack market liquidity. Fair values for loan receivables are determined based on the present value of expected future cash flows discounted at the applicable U.S. Treasury or London Interbank Offered Rate (LIBOR) yield plus an appropriate spread that considers other risk factors, such as credit and liquidity risk. These spreads are provided by the applicable asset managers based on their knowledge of the current loan pricing environment and market conditions. The spreads are a significant component of the pricing inputs and are generally considered unobservable. Therefore, these investments have been assigned a Level 3 within the fair value hierarchy. Other investments Other investments includes short-term investments that are measured at fair value where amortized cost approximates fair value. Other policyholders' funds The largest component of the other policyholders' funds liability is the Company's annuity line of business in Aflac Japan. The Company's annuities have fixed benefits and premiums. For this product, the Company estimates the fair value to be equal to the cash surrender value. This is analogous to the value paid to policyholders on the valuation date if they were to surrender their policy. The Company periodically checks the cash value against discounted cash flow projections for reasonableness. The Company considers its inputs for this valuation to be unobservable and have accordingly classified this valuation as Level 3. Notes payable Transfers between Hierarchy Levels and Level 3 Rollforward There were no transfers between Level 1 and 2 for assets and liabilities that are measured and carried at fair value on a recurring basis for the years ended December 31, 2019 and 2018 , respectively. The following tables present the changes in fair value of the Company's investments and derivatives carried at fair value classified as Level 3 as of December 31. 2019 Fixed Maturity Securities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 177 $ 109 $ 23 $ 213 $ 46 $ 80 $ 0 $ 648 Realized investment gains (losses) included 0 0 0 (1 ) 0 (33 ) 0 (34 ) Unrealized gains (losses) included in other 1 6 1 8 0 (4 ) 0 12 Purchases, issuances, sales and settlements: Purchases 0 48 0 165 34 0 0 247 Issuances 0 0 0 0 0 0 0 0 Sales 0 (24 ) 0 (17 ) 0 0 0 (41 ) Settlements 0 (6 ) 0 0 0 0 0 (6 ) Transfers into Level 3 0 116 (2) 0 26 (2) 0 0 0 142 Transfers out of Level 3 0 (25 ) (2) (1 ) (132 ) (2), (3) 0 0 0 (158 ) Balance, end of period $ 178 $ 224 $ 23 $ 262 $ 80 $ 43 $ 0 $ 810 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ (33 ) $ 0 $ (33 ) (1) Derivative assets and liabilities are presented net (2) Transfer due to sector classification change (3) Transfer due to availability of observable market inputs 2018 Fixed Maturity Securities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 175 $ 68 $ 25 $ 146 $ 16 $ 22 $ 1 $ 453 Realized investment gains (losses) included in 0 0 0 0 (1 ) 54 (1 ) 52 Unrealized gains (losses) included in other 2 1 (2 ) 1 0 4 0 6 Purchases, issuances, sales and settlements: Purchases 0 40 0 56 31 0 0 127 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 0 0 0 0 Settlements 0 0 0 (6 ) 0 0 0 (6 ) Transfers into Level 3 0 0 0 16 0 0 0 16 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 177 $ 109 $ 23 $ 213 $ 46 $ 80 $ 0 $ 648 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ (1 ) $ 54 $ (1 ) $ 52 (1) Derivative assets and liabilities are presented net Level 3 Significant Unobservable Input Sensitivity The following tables summarize the significant unobservable inputs used in the valuation of the Company's Level 3 investments and derivatives carried at fair value as of December 31. Included in the tables are the inputs or range of possible inputs that have an effect on the overall valuation of the financial instruments. 2019 (In millions) Fair Value Valuation Technique(s) Unobservable Input Range Assets: Securities available for sale, carried at fair value: Fixed maturity securities: Mortgage- and asset-backed securities $ 178 Consensus pricing Offered quotes N/A (a) Public utilities 224 Discounted cash flow Credit spreads N/A (a) Banks/financial institutions 23 Consensus pricing Offered quotes N/A (a) Other corporate 262 Discounted cash flow Credit spreads N/A (a) Equity securities 80 Net asset value Offered quotes N/A (a) Other assets: Foreign currency swaps 106 Discounted cash flow Interest rates (USD) 1.89% - 2.09% (b) Interest rates (JPY) .12% - .43% (c) CDS spreads 10 - 100 bps 63 Discounted cash flow Interest rates (USD) 1.89% - 2.09% (b) Interest rates (JPY) .12% - .43% (c) Total assets $ 936 Liabilities: Other liabilities: Foreign currency swaps $ 118 Discounted cash flow Interest rates (USD) 1.89% - 2.09% (b) Interest rates (JPY) .12% - .43% (c) CDS spreads 13 - 159 bps 8 Discounted cash flow Interest rates (USD) 1.89% - 2.09% (b) Interest rates (JPY) .12% - .43% (c) Total liabilities $ 126 (a) N/A represents securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques or unobservable inputs. (b) Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps (c) Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps 2018 (In millions) Fair Value Valuation Technique(s) Unobservable Input Range Assets: Securities available for sale, carried at fair value: Fixed maturity securities: Mortgage- and asset-backed securities $ 177 Consensus pricing Offered quotes N/A (a) Public utilities 109 Discounted cash flow Credit spreads N/A (a) Banks/financial institutions 23 Consensus pricing Offered quotes N/A (a) Other corporate 213 Discounted cash flow Credit spreads N/A (a) Equity securities 46 Net asset value Offered quotes N/A (a) Other assets: Foreign currency swaps 125 Discounted cash flow Interest rates (USD) 2.75% - 2.84% (b) Interest rates (JPY) .18% - .71% (c) CDS spreads 19 - 120 bps 57 Discounted cash flow Interest rates (USD) 2.75% - 2.84% (b) Interest rates (JPY) .18% - .71% (c) Total assets $ 750 Liabilities: Other liabilities: Foreign currency swaps $ 98 Discounted cash flow Interest rates (USD) 2.75% - 2.84% (b) Interest rates (JPY) .18% - .71% (c) CDS spreads 28 - 211 bps 4 Discounted cash flow Interest rates (USD) 2.75% - 2.84% (b) Interest rates (JPY) .18% - .71% (c) Total liabilities $ 102 (a) N/A represents securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques or unobservable inputs. (b) Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps (c) Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps The following is a discussion of the significant unobservable inputs or valuation techniques used in determining the fair value of securities and derivatives classified as Level 3. Net Asset Value The Company holds certain unlisted equity securities whose fair value is derived based on the financial statements published by the investee. These securities do not trade on an active market and the valuations derived are dependent on the availability of timely financial reporting of the investee. Net asset value is an unobservable input in the determination of fair value of equity securities. Offered Quotes In circumstances where the Company's valuation model price is overridden because it implies a value that is not consistent with current market conditions, the Company will solicit bids from a limited number of brokers. The Company also receives unadjusted prices from brokers for its mortgage and asset-backed securities. These quotes are non-binding but are reflective of valuation best estimates at that particular point in time. Offered quotes are an unobservable input in the determination of fair value of mortgage- and asset-backed securities, certain banks/financial institutions, certain other corporate, and equity securities investments. Interest Rates and CDS Spreads The significant drivers of the valuation of the foreign exchange swaps are interest rates and CDS spreads. Some of the Company's swaps have long maturities that increase the sensitivity of the swaps to interest rate fluctuations. For the Company's foreign exchange or cross currency swaps that are in a net asset position, an increase in yen interest rates (all other factors held constant) will decrease the present value of the yen final settlement receivable (receive leg), thus decreasing the value of the swap as long as the derivative remains in a net asset position. Foreign exchange swaps also have a lump-sum final settlement of foreign exchange principal amounts at the termination of the swap. Assuming all other factors are held constant, an increase in yen interest rates will decrease the receive leg and decrease the net value of the swap. Likewise, holding all other factors constant, an increase in U.S. dollar interest rates will increase the swap's net value due to the decrease in the present value of the dollar final settlement payable (pay leg). The extinguisher feature in most of the Company's VIE swaps results in a cessation of cash flows and no further payments between the parties to the swap in the event of a default on the referenced or underlying collateral. To price this feature, the Company applies the survival probability of the referenced entity to the projected cash flows. The survival probability uses the CDS spreads and recovery rates to adjust the present value of the cash flows. For extinguisher swaps with positive values, an increase in CDS spreads decreases the likelihood of receiving the final exchange payments and reduces the value of the swap. For additional information on the Company's investments and financial instruments, see the accompanying Notes 1, 3 and 4.

DEFERRED POLICY ACQUISITION COS

DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES	12 Months Ended
DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES	Dec. 31, 2019
Deferred Policy Acquisition Costs Disclosures [Abstract]
DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES	DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES Consolidated policy acquisition costs deferred were $1.5 billion in 2019 , 2018 and 2017 . The following table presents a rollforward of deferred policy acquisition costs by segment for the years ended December 31. 2019 2018 (In millions) Japan U.S. Japan U.S. Deferred policy acquisition costs: Balance, beginning of year $ 6,384 $ 3,491 $ 6,150 $ 3,355 Capitalization 825 626 833 669 Amortization (709 ) (573 ) (710 ) (534 ) Foreign currency translation and other 84 0 111 1 Balance, end of year $ 6,584 $ 3,544 $ 6,384 $ 3,491 Commissions deferred as a percentage of total acquisition costs deferred were 74% in 2019 , compared with 72% in both 2018 and 2017 . Personnel, compensation and benefit expenses as a percentage of insurance expenses were 57% in 2019 , compared with 54% in 2018 and 56% in 2017 . Advertising expense, which is included in insurance expenses in the consolidated statements of earnings, was as follows for the years ended December 31: (In millions) 2019 2018 2017 Advertising expense: Aflac Japan $ 101 $ 108 $ 100 Aflac U.S. 118 110 110 Total advertising expense $ 219 $ 218 $ 210 Depreciation and other amortization expenses, which are included in insurance expenses in the consolidated statements of earnings, were as follows for the years ended December 31: (In millions) 2019 2018 2017 Depreciation expense $ 40 $ 48 $ 50 Other amortization expense 1 1 3 Total depreciation and other amortization expense $ 41 $ 49 $ 53

POLICY LIABILITIES

POLICY LIABILITIES	12 Months Ended
POLICY LIABILITIES	Dec. 31, 2019
Insurance Loss Reserves [Abstract]
POLICY LIABILITIES	POLICY LIABILITIES Policy liabilities consist of future policy benefits, unpaid policy claims, unearned premiums, and other policyholders' funds, which accounted for 85% , 4% , 4% and 7% of total policy liabilities at December 31, 2019 , respectively. The Company regularly reviews the adequacy of its policy liabilities in total and by component. The liability for future policy benefits as of December 31 consisted of the following: Liability Amounts Interest Rate Assumptions (In millions) 2019 2018 Health insurance Japan $ 50,941 $ 49,496 0.6 - 6.75 % U.S. 8,646 8,442 3.0 - 7.0 Intercompany eliminations (532 ) (1) (583 ) (1) 2.0 Life insurance Japan 30,520 28,318 1.0 - 4.5 U.S. 760 695 2.5 - 6.0 Total $ 90,335 $ 86,368 (1) Elimination entry necessary due to recapture of a portion of policy liabilities ceded externally, as a result of the reinsurance retrocession transaction as described in Note 8 of the Notes to the Consolidated Financial Statements The weighted-average interest rates reflected in the consolidated statements of earnings for future policy benefits for Japanese policies were 3.2% in 2019 , compared with 3.3% in 2018 and 3.4% in 2017 ; and for U.S. policies, 5.3% in 2019 , compared with 5.3% in 2018 and 5.4% in 2017 . Changes in the liability for unpaid policy claims were as follows for the years ended December 31: (In millions) 2019 2018 2017 Unpaid supplemental health claims, beginning of period $ 3,952 $ 3,884 $ 3,707 Less reinsurance recoverables 27 30 27 Net balance, beginning of period 3,925 3,854 3,680 Add claims incurred during the period related to: Current year 7,216 7,101 6,979 Prior years (552 ) (563 ) (518 ) Total incurred 6,664 6,538 6,461 Less claims paid during the period on claims incurred during: Current year 4,715 4,612 4,530 Prior years 1,965 1,898 1,822 Total paid 6,680 6,510 6,352 Effect of foreign exchange rate changes on unpaid claims 29 43 65 Net balance, end of period 3,938 3,925 3,854 Add reinsurance recoverables 30 27 30 Unpaid supplemental health claims, end of period 3,968 3,952 3,884 Unpaid life claims, end of period 691 632 508 Total liability for unpaid policy claims $ 4,659 $ 4,584 $ 4,392 The incurred claims development related to prior years reflects favorable claims experience compared to previous estimates. The favorable claims development of $552 million for 2019 comprises approximately $395 million from Japan, which represents approximately 72% of the total. Excluding the impact of foreign exchange of a gain of approximately $5 million from December 31, 2018 to December 31, 2019 , the favorable claims development in Japan would have been approximately $390 million , representing approximately 71% of the total. The Company has experienced continued favorable claim trends in 2019 for its core health products in Japan. The Company's experience in Japan related to the average length of stay in the hospital for cancer treatment has shown continued decline in the current period. In addition, cancer treatment patterns in Japan are continuing to be influenced by significant advances in early-detection techniques and by the increased use of pathological diagnosis rather than clinical exams. Additionally, follow-up radiation and chemotherapy treatments are occurring more often on an outpatient basis. Such changes in treatment not only increase the quality of life and initial outcomes for the patients, but also decrease the average length of each hospital stay, resulting in favorable claims development. As of December 31, 2019 and 2018 , unearned premiums consisted primarily of discounted advance premiums on deposit. Discounted advance premiums are premiums on deposit from policyholders in conjunction with their purchase of certain Aflac Japan limited-pay insurance products. These advanced premiums are deferred upon collection and recognized as premium revenue over the contractual premium payment period. These advanced premiums represented 64% of the December 31, 2019 and 69% of the December 31, 2018 unearned premiums balances. As of December 31, 2019 and 2018 , the largest component of the other policyholders' funds liability was the Company's annuity line of business in Aflac Japan. The Company's annuities have fixed benefits and premiums. These annuities represented 97% of other policyholders' funds liability at December 31, 2019 and 2018 .

REINSURANCE

REINSURANCE	12 Months Ended
REINSURANCE	Dec. 31, 2019
Reinsurance Disclosures [Abstract]
REINSURANCE	REINSURANCE The Company periodically enters into fixed quota-share coinsurance agreements with other companies in the normal course of business. For each of its reinsurance agreements, the Company determines whether the agreement provides indemnification against loss or liability relating to insurance risk in accordance with applicable accounting standards. Reinsurance premiums and benefits paid or provided are accounted for on bases consistent with those used in accounting for the original policies issued and the terms of the reinsurance contracts. Premiums and benefits are reported net of insurance ceded. The Company has recorded a deferred profit liability related to reinsurance transactions. The remaining deferred profit liability of $1.0 billion , as of December 31, 2019 , is included in future policy benefits in the consolidated balance sheet and is being amortized into income over the expected lives of the policies. The Company has also recorded a reinsurance recoverable for reinsurance transactions, which is included in other assets in the consolidated balance sheet and had a remaining balance of $970 million and $941 million as of December 31, 2019 and 2018 , respectively. The increase in the reinsurance recoverable balance was driven by two aggregating factors: yen strengthening and the growth in reserves related to the business that has been reinsured as the policies age. The spot yen/dollar exchange rate strengthened by approximately 1.3% and ceded reserves increased approximately 1.4% from December 31, 2018 , to December 31, 2019 . The following table reconciles direct premium income and direct benefits and claims to net amounts after the effect of reinsurance for the years ended December 31. (In millions) 2019 2018 2017 Direct premium income $ 19,122 $ 19,018 $ 18,875 Ceded to other companies: Ceded Aflac Japan closed blocks (478 ) (497 ) (515 ) Other (69 ) (58 ) (51 ) Assumed from other companies: Retrocession activities 200 208 216 Other 5 6 6 Net premium income $ 18,780 $ 18,677 $ 18,531 Direct benefits and claims $ 12,237 $ 12,293 $ 12,486 Ceded benefits and change in reserves for future benefits: Ceded Aflac Japan closed blocks (433 ) (450 ) (473 ) Eliminations 41 43 51 Other (57 ) (44 ) (44 ) Assumed from other companies: Retrocession activities 194 209 209 Eliminations (41 ) (53 ) (51 ) Other 1 2 3 Benefits and claims, net $ 11,942 $ 12,000 $ 12,181 These reinsurance transactions are indemnity reinsurance that do not relieve the Company from its obligations to policyholders. In the event that the reinsurer is unable to meet their obligations, the Company remains liable for the reinsured claims. As a part of its capital contingency plan, the Company entered into a committed reinsurance facility agreement on December 1, 2015 in the amount of approximately ¥110 billion of reserves. This reinsurance facility agreement was renewed in 2019 and is effective until December 31, 2020. There are also additional commitment periods of a one-year duration each of which are automatically extended unless notification is received from the reinsurer within 60 days prior to the expiration. The reinsurer can withdraw from the committed facility if Aflac‘s Standard and Poor's (S&P) rating drops below BBB-. As of December 31, 2019 , the Company had not executed a reinsurance treaty under this committed reinsurance facility.

NOTES PAYABLE

NOTES PAYABLE	12 Months Ended
NOTES PAYABLE	Dec. 31, 2019
Debt Disclosure [Abstract]
NOTES PAYABLE	NOTES PAYABLE AND LEASE OBLIGATIONS A summary of notes payable and lease obligations as of December 31 follows: (In millions) 2019 2018 4.00% senior notes due February 2022 (1) $ 348 $ 348 3.625% senior notes due June 2023 698 698 3.625% senior notes due November 2024 747 746 3.25% senior notes due March 2025 448 447 2.875% senior notes due October 2026 298 297 6.90% senior notes due December 2039 220 220 6.45% senior notes due August 2040 254 254 4.00% senior notes due October 2046 394 394 4.750% senior notes due January 2049 541 540 Yen-denominated senior notes and subordinated debentures: .932% senior notes due January 2027 (principal amount ¥60.0 billion) 545 538 .500% senior notes due December 2029 (principal amount ¥12.6 billion) 114 0 1.159% senior notes due October 2030 (principal amount ¥29.3 billion) 266 262 .843% senior notes due December 2031 (principal amount ¥9.3 billion) 84 0 1.488% senior notes due October 2033 (principal amount ¥15.2 billion) 138 136 .934% senior notes due December 2034 (principal amount ¥9.8 billion) 88 0 1.750% senior notes due October 2038 (principal amount ¥8.9 billion) 81 79 1.122% senior notes due December 2039 (principal amount ¥6.3 billion) 57 0 2.108% subordinated debentures due October 2047 (principal amount ¥60.0 billion) 543 536 .963% subordinated bonds due April 2049 (principal amount ¥30.0 billion) 272 0 Yen-denominated loans: Variable interest rate loan due September 2026 (.42% in 2019 and .32% in 2018, principal amount ¥5.0 billion) 45 45 Variable interest rate loan due September 2029 (.57% in 2019 and .47% in 2018, principal amount ¥25.0 billion) 227 225 Finance lease obligations payable through 2026 12 13 Operating lease obligations payable through 2049 (2) 149 0 Total notes payable and lease obligations $ 6,569 $ 5,778 (1) Redeemed in January 2020 (2) See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2019 related to leases. Amounts in the table above are reported net of debt issuance costs and issuance premiums or discounts, if applicable, that are being amortized over the life of the notes. In December 2019, the Parent Company issued four series of senior notes totaling ¥38.0 billion through a public debt offering under its U.S. shelf registration statement. The first series, which totaled ¥12.6 billion , bears interest at a fixed rate of .500% per annum, payable semi-annually, and will mature in December 2029. The second series, which totaled ¥9.3 billion , bears interest at a fixed rate of .843% per annum, payable semi-annually, and will mature in December 2031. The third series, which totaled ¥9.8 billion , bears interest at a fixed rate of .934% per annum, payable semi-annually, and will mature in December 2034. The fourth series, which totaled ¥6.3 billion , bears interest at a fixed rate of 1.122% per annum, payable semi-annually, and will mature in December 2039. These notes may only be redeemed before maturity, in whole but not in part, upon the occurrence of certain changes affecting U.S. taxation, as specified in the indenture governing the terms of the issuance. In September 2019, the Parent Company renewed a ¥30.0 billion senior term loan facility. The first tranche of the facility, which totaled ¥5.0 billion , bears interest at a rate per annum equal to the Tokyo interbank market rate (TIBOR), or alternate TIBOR, if applicable, plus the applicable TIBOR margin and will mature in September 2026. The applicable margin ranges between .30% and .70% , depending on the Parent Company's debt ratings as of the date of determination. The second tranche, which totaled ¥25.0 billion , bears interest at a rate per annum equal to the TIBOR, or alternate TIBOR, if applicable, plus the applicable TIBOR margin and will mature in September 2029. The applicable margin ranges between .45% and 1.00% , depending on the Parent Company's debt ratings as of the date of determination. In April 2019, ALIJ issued ¥30.0 billion (par value) of perpetual subordinated bonds. These bonds bear interest at a fixed rate of .963% per annum and then at six-month Euro Yen LIBOR plus an applicable spread on and after the day immediately following April 18, 2024. The bonds will be callable on each interest payment date on and after April 18, 2024. In November 2019, ALIJ amended the bonds to change their duration from perpetual to a stated maturity date of April 16, 2049 and to remove provisions that permitted ALIJ to defer payments of interest under certain circumstances. In October 2018, the Parent Company issued $550 million of senior notes through a U.S. public debt offering. The notes bear interest at a fixed rate of 4.750% per annum, payable semi-annually, and will mature in January 2049. These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the yield to maturity for a U.S.Treasury security with a maturity comparable to the remaining term of the notes, plus 25 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date. In October 2018, the Parent Company issued three series of senior notes totaling ¥53.4 billion through a public debt offering under its U.S. shelf registration statement. The first series, which totaled ¥29.3 billion , bears interest at a fixed rate of 1.159% per annum, payable semi-annually, and will mature in October 2030. The second series, which totaled ¥15.2 billion , bears interest at a fixed rate of 1.488% per annum, payable semi-annually, and will mature in October 2033. The third series, which totaled ¥8.9 billion , bears interest at a fixed rate of 1.750% per annum, payable semi-annually, and will mature in October 2038. These notes may only be redeemed before maturity, in whole but not in part, upon the occurrence of certain changes affecting U.S. taxation, as specified in the indenture governing the terms of the issuance. In October 2017, the Parent Company issued ¥60.0 billion of subordinated debentures through a U.S. public debt offering. The debentures bear interest at an initial rate of 2.108% per annum through October 22, 2027, or earlier redemption. Thereafter, the rate of the interest of the debentures will be reset every five years at a rate of interest equal to the then-current JPY 5-year Swap Offered Rate plus 205 basis points. The debentures are payable semi-annually in arrears and will mature in October 2047. The debentures are redeemable (i) at any time, in whole but not in part, upon the occurrence of certain tax events or certain rating agency events, as specified in the indenture governing the terms of the debentures or (ii) on or after October 23, 2027, in whole or in part, at a redemption price equal to their principal amount plus accrued and unpaid interest to, but excluding, the date of redemption. In January 2017, the Parent Company issued ¥60.0 billion of senior notes through a U.S. public debt offering. The notes bear interest at a fixed rate of .932% per annum, payable semi-annually, and will mature in January 2027. These notes may only be redeemed before maturity, in whole but not in part, upon the occurrence of certain changes affecting U.S. taxation, as specified in the indenture governing the terms of the issuance. In September 2016, the Parent Company issued two series of senior notes totaling $700 million through a U.S. public debt offering. The first series, which totaled $300 million , bears interest at a fixed rate of 2.875% per annum, payable semi-annually and will mature in October 2026. The second series, which totaled $400 million , bears interest at a fixed rate of 4.00% per annum, payable semi-annually, and will mature in October 2046. In March 2015, the Parent Company issued $450 million of senior notes through a U.S. public debt offering. The notes bear interest at a fixed rate of 3.25% per annum, payable semi-annually, and will mature in March 2025. The Parent Company entered into cross-currency swaps that convert the U.S. dollar-denominated principal and interest on the senior notes into yen-denominated obligations which results in lower nominal net interest rates on the debt. By entering into these cross-currency swaps, the Parent Company economically converted its $450 million liability into a ¥55.0 billion yen liability and reduced the interest rate on this debt from 3.25% in dollars to .82% in yen. In November 2014, the Parent Company issued $750 million of senior notes through a U.S. public debt offering. The notes bear interest at a fixed rate of 3.625% per annum, payable semi-annually, and will mature in November 2024. These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the treasury rate plus 20 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date. The Parent Company entered into cross-currency interest rate swaps to reduce interest expense by converting the U.S. dollar-denominated principal and interest on the senior notes it issued into yen-denominated obligations. By entering into the swaps, the Parent Company economically converted its $750 million liability into an ¥85.3 billion liability and reduced the interest rate on this debt from 3.625% in dollars to 1.00% in yen. In June 2013, the Parent Company issued $700 million of senior notes through a U.S. public debt offering. The notes bear interest at a fixed rate of 3.625% per annum, payable semi-annually, and will mature in June 2023. These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the treasury rate plus 20 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date. The Parent Company had entered into cross-currency interest rate swaps to reduce interest expense by converting the U.S. dollar-denominated principal and interest on the senior notes it issued into yen-denominated obligations. By entering into these swaps, the Parent Company economically converted its $700 million liability into a ¥69.8 billion liability and reduced the interest rate on this debt from 3.625% in dollars to 1.50% in yen. In February 2012, the Parent Company issued $350 million of senior notes through a U.S. public debt offering. The notes bear interest at a fixed rate of 4.00% per annum, payable semiannually, and will mature in February 2022. These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the principal amount of the notes or (ii) the present value of the remaining scheduled payments of principal and interest to be redeemed, discounted to the redemption date, plus accrued and unpaid interest. The Parent Company entered into cross-currency interest rate swaps to reduce interest expense by converting the U.S. dollar-denominated principal and interest on the senior notes it issued into yen-denominated obligations. By entering into these swaps, the Parent Company economically converted its $350 million liability into a ¥27.0 billion liability and reduced the interest rate on this debt from 4.00% in dollars to 2.07% in yen. In 2010 and 2009, the Parent Company issued senior notes through U.S. public debt offerings; the details of these notes are as follows. In August 2010, the Parent Company issued $450 million of senior notes that will mature in August 2040. In December 2009, the Parent Company issued $400 million of senior notes that will mature in December 2039. These senior notes pay interest semiannually and are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the principal amount of the notes or (ii) the present value of the remaining scheduled payments of principal and interest to be redeemed, discounted to the redemption date, plus accrued and unpaid interest. In December 2016, the Parent Company completed a tender offer in which it extinguished $176 million principal of its 6.90% senior notes due December 2039 and $193 million principal of its 6.45% senior notes due August 2040. The pretax loss due to the early redemption of these notes was $137 million . For the Company's yen-denominated notes and loans, the principal amount as stated in dollar terms will fluctuate from period to period due to changes in the yen/dollar exchange rate. The Company has designated the majority of its yen-denominated notes payable as a nonderivative hedge of the foreign currency exposure of the Company's investment in Aflac Japan. The aggregate contractual maturities of notes payable during each of the years after December 31, 2019 , are as follows: (In millions) Total 2020 $ 0 2021 0 2022 350 2023 700 2024 750 Thereafter 4,658 Total $ 6,458 The following table presents the contractual maturities and present value of lease liabilities as of December 31. 2019 (In millions) Operating Leases Finance Leases Total 2020 $ 49 $ 4 $ 53 2021 37 3 40 2022 31 2 33 2023 10 2 12 2024 10 1 11 After 2024 22 0 22 Total lease payments $ 159 $ 12 $ 171 Less: Interest 10 0 10 Present value of lease liabilities $ 149 $ 12 $ 161 The following table presents the weighted average remaining lease term and weighted average discount rate for lease liabilities as of December 31. 2019 Weighted average remaining lease term (years): Operating leases 6.8 Finance leases 3.7 Weighted average discount rate: Operating leases 2.1% Finance leases 1.5% Operating lease costs, included in insurance expenses in the consolidated statements of earnings, were $54 million , $73 million and $75 million for the years ended December 31, 2019 , 2018 and 2017, respectively. Operating cash outflow for operating leases was $52 million for the year ended December 31, 2019 A summary of the Company's lines of credit as of December 31, 2019 follows: Borrower Type Original Term Expiration Date Capacity Amount Outstanding Interest Rate on Borrowed Amount Maturity Period Commitment Fee Business Purpose Aflac Incorporated uncommitted bilateral 364 days December 18, 2020 $100 million $0 million The rate quoted by the bank and agreed upon at the time of borrowing Up to 3 months None General corporate purposes Aflac Incorporated unsecured revolving 5 years March 29, ¥100.0 billion ¥0.0 billion A rate per annum equal to (a) Tokyo interbank market rate (TIBOR) plus, the alternative applicable TIBOR margin during the availability period from the closing date to the commitment termination date or (b) the TIBOR rate offered by the agent to major banks in yen for the applicable period plus, the applicable alternative TIBOR margin during the term out period No later than .30% to .50%, depending on the Parent Company's debt ratings as of the date of determination General corporate purposes, including a capital contingency plan for the operations of the Parent Company Aflac Incorporated unsecured revolving 5 years November 18, 2024, or the date commitments are terminated pursuant to an event of default $1.0 billion $0.0 billion A rate per annum equal to, at the Company's option, either, (a) the rate for Eurocurrency for deposits in the London interbank market for a period of one, two, three or six months (LIBOR) or (b) a base rate determined by reference to the highest of (1) the federal funds rate plus 1/2 of 1%, (2) the rate of interest in effect for such day as publicly announced from time to time by Mizuho as its “prime rate”, and (3) the LIBOR for a one month interest period in effect on such day (or if such day is not a business day, the immediately preceding business day) plus 1.00%, and in each case an applicable margin No later than November 18, 2024 .085% to General corporate purposes, including a capital contingency plan for the operations of the Parent Company Aflac Incorporated uncommitted bilateral None specified None specified $50 million $0 million A rate per annum equal to, at the Parent Company's option, either (a) a eurocurrency rate determined by reference to the agent's LIBOR for the interest period relevant to such borrowing or (b) the base rate determined by reference to the greater of (i) the prime rate as determined by the agent, and (ii) the sum of 0.50% and the federal funds rate for such day Up to 3 months None General corporate purposes Aflac (1) uncommitted revolving 364 days November 30, 2020 $250 million $0 million USD three-month LIBOR plus 75 basis points per annum 3 months None General corporate purposes Aflac Incorporated (1) uncommitted revolving 364 days April 2, 2020 ¥50.0 billion ¥0.0 billion Three-month TIBOR plus 70 basis points per annum 3 months None General corporate purposes Aflac Incorporated (1) uncommitted revolving 364 days November 25, 2020 ¥50.0 billion ¥0.0 billion Three-month TIBOR plus 70 basis points per annum 3 months None General corporate purposes (1) Intercompany credit agreement The Parent Company was in compliance with all of the covenants of its notes payable and lines of credit at December 31, 2019 . No events of default or defaults occurred during 2019 and 2018 .

INCOME TAXES

INCOME TAXES	12 Months Ended
INCOME TAXES	Dec. 31, 2019
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The components of income tax expense (benefit) applicable to pretax earnings for the years ended December 31 were as follows: (In millions) Foreign U.S. Total 2019: Current $ 737 $ 69 $ 806 Deferred 183 152 335 Total income tax expense $ 920 $ 221 $ 1,141 2018: Current $ 771 $ 608 $ 1,379 Deferred 93 (409 ) (316 ) Total income tax expense $ 864 $ 199 $ 1,063 2017: Current $ 722 $ (91 ) $ 631 Deferred (24 ) (1,193 ) (1,217 ) Total income tax expense $ 698 $ (1,284 ) $ (586 ) The Japan income tax rate for the fiscal year 2017 was 28.2% . The rate was reduced to 28.0% for fiscal years 2018 and 2019. For the U.S., the Tax Cuts and Jobs Act (Tax Act) was signed into law on December 22, 2017. Effective January 1, 2018, the Tax Act imposed a broad number of changes in tax law, including permanently reducing the U.S. federal statutory corporate income tax rate from 35% to 21% , eliminating or reducing certain deductions and credits and limiting the deductibility of interest expense and executive compensation. In accordance with Staff Accounting Bulletin 118 (SAB 118) issued by the U.S. Securities and Exchange Commission in December 2017, the Company recorded provisional amounts for certain items for which the income tax accounting was not complete. As of the enactment date, the Company estimated provisional amounts for its deferred taxes, including related valuation allowance, resulting in a reduction of its DTAs by approximately $1.0 billion and its deferred tax liabilities (DTLs) by $2.9 billion , for a net DTL reduction of approximately $1.9 billion . The provisions of ASC 740-10, Income Taxes , require that the effects of changes in tax law on deferred taxes be recognized as a component of the income tax provision in the period the tax rate change was enacted. Therefore, the $1.9 billion provisional amount of net DTL reduction was recorded in the fourth quarter of 2017 as a reduction in the “Income tax expense, Deferred” line item of the Company’s consolidated statement of earnings. In 2018, the Company recorded additional income tax expense of $.4 million resulting from a decrease in the SAB 118 provisional estimate related to Japan deferred tax balances. No further adjustment was made to the SAB 118 provisional estimate related to the valuation allowance. As of December 31, 2018, the Company has completed its accounting for the Tax Act in accordance with SAB 118. Income tax expense in the accompanying statements of earnings varies from the amount computed by applying the expected U.S. tax rate of 21% in both 2019 and 2018 and 35% in 2017 to pretax earnings. The principal reasons for the differences and the related tax effects for the years ended December 31 were as follows: (In millions) 2019 2018 2017 Income taxes based on U.S. statutory rates $ 933 $ 836 $ 1,406 Foreign rate differential 229 220 0 Write-down of U.S. deferred tax liabilities for tax reform change 0 0 (1,933 ) Utilization of foreign tax credit (6 ) (3 ) (27 ) Nondeductible expenses 10 21 10 Other, net (25 ) (11 ) (42 ) Income tax expense $ 1,141 $ 1,063 $ (586 ) Total income tax expense for the years ended December 31 was allocated as follows: (In millions) 2019 2018 2017 Statements of earnings $ 1,141 $ 1,063 $ (586 ) Other comprehensive income (loss): Unrealized foreign currency translation gains (losses) during period 27 10 52 Unrealized gains (losses) on investment securities: Unrealized holding gains (losses) on investment 1,532 (787 ) 575 Reclassification adjustment for realized (gains) losses 5 (12 ) 1 Unrealized gains (losses) on derivatives during period (3 ) 0 0 Pension liability adjustment during period (18 ) (8 ) 3 Total income tax expense (benefit) related to items of 1,543 (797 ) 631 Total income taxes $ 2,684 $ 266 $ 45 The income tax effects of the temporary differences that gave rise to deferred income tax assets and liabilities as of December 31 were as follows: (In millions) 2019 2018 Deferred income tax liabilities: Deferred policy acquisition costs $ 3,492 $ 3,404 Unrealized gains and other basis differences on investments 4,485 1,307 Premiums receivable 152 149 Policy benefit reserves 3,442 3,828 Total deferred income tax liabilities 11,571 8,688 Deferred income tax assets: Unfunded retirement benefits 8 8 Other accrued expenses 36 40 Policy and contract claims 781 775 Foreign currency loss on Aflac Japan 16 38 Deferred compensation 162 163 Capital loss carryforwards 34 5 Depreciation 164 119 Anticipatory foreign tax credit 5,487 4,040 Deferred foreign tax credit 605 591 Other 204 150 Total deferred income tax assets before valuation allowance 7,497 5,929 Valuation allowance (1,340 ) (738 ) Total deferred income tax assets after valuation allowance 6,157 5,191 Net deferred income tax liability 5,414 3,497 Current income tax (asset) liability (44 ) 523 Total income tax liability $ 5,370 $ 4,020 The application of U.S. GAAP requires the Company to evaluate the recoverability of deferred tax assets and establish a valuation allowance if necessary to reduce the deferred tax asset to an amount that is more likely than not expected to be realized. The Company has determined a $1,022 million valuation allowance against its anticipatory foreign tax credit is necessary. The anticipatory foreign tax credit represents the foreign tax credit the Company will generate from the reversal of Japan deferred tax liabilities in the future. The increase in the valuation allowance on the anticipatory foreign tax credit is due to an increase Japan's local country deferred tax inventory relative to the deferred tax inventory for Japan's U.S. tax obligation. The Company has also determined a $318 million valuation allowance against its deferred foreign tax credits is necessary. Deferred foreign tax credits are foreign tax credits generated in the current tax year by the Japanese life company, but are unable to be utilized until 2020 due to Japan's current tax year not closing until March 31, 2020. The valuation allowance on the deferred foreign tax credit has increased due to the utilization of prior year credits as well as the recognition of the current year deferred foreign tax credit. Based upon a review of the Company's anticipated future taxable income, and including all other available evidence, both positive and negative, the Company's management has concluded that, notwithstanding the items noted above, it is more likely than not that all other deferred tax assets will be realized. Under U.S. income tax rules, only 35% of non-life operating losses can be offset against life insurance taxable income each year . For current U.S. income tax purposes, as of December 31, 2019 , there were non-life operating loss carryforwards of $99 million available to offset against future taxable income, of which $31 million expires in 2039, and $68 million does not expire. The Company has capital loss carryforwards of $161 million available to offset capital gains, of which $65 million expires in 2023 and $96 million expires in 2024. The Company files federal income tax returns in the U.S. and Japan as well as state or prefecture income tax returns in various jurisdictions in the two countries. The Company is currently under audit by the IRS for the 2013-2016 amended federal income tax returns. There are currently no other open Federal, State, or local U.S. income tax audits. U.S. federal income tax returns for years before 2016 are no longer subject to examination. Japan corporate income tax returns for years before 2016 are no longer subject to examination. Management believes it has established adequate tax liabilities and final resolution of all open audits is not expected to have a material impact on the Company's consolidated financial statements. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows for the years ended December 31: (In millions) 2019 2018 Balance, beginning of year $ 15 $ 14 Additions for tax positions of prior years 2 1 Balance, end of year $ 17 $ 15 Included in the balance of the liability for unrecognized tax benefits at December 31, 2019 , are $15 million of tax positions for which the ultimate deductibility is highly certain, but for which there is uncertainty about the timing of such deductibility, compared with $14 million at December 31, 2018 . Because of the impact of deferred tax accounting, other than interest and penalties, the disallowance of the shorter deductibility period would not affect the annual effective tax rate, but would accelerate the payment of cash to the taxing authority to an earlier period. The Company has accrued approximately $2 million as of December 31, 2019 , for permanent uncertainties, which if reversed would not have a material effect on the annual effective rate. The Company recognizes accrued interest and penalties related to unrecognized tax benefits in income tax expense. The Company recognized approximately $1 million in interest and penalties in 2019 , 2018 and 2017 , respectively. The Company has accrued approximately $2 million for the payment of interest and penalties as of December 31, 2019 , compared with $2 million at December 31, 2018 . As of December 31, 2019 , there were no material uncertain tax positions for which the total amounts of unrecognized tax benefits will significantly increase or decrease within the next 12 months.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	12 Months Ended
SHAREHOLDERS' EQUITY	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS' EQUITY The following table is a reconciliation of the number of shares of the Company's common stock for the years ended December 31. (In thousands of shares) 2019 2018 2017 Common stock - issued: Balance, beginning of period 1,347,540 1,345,762 1,342,498 Exercise of stock options and issuance of restricted shares 1,769 1,778 3,264 Balance, end of period 1,349,309 1,347,540 1,345,762 Treasury stock: Balance, beginning of period 592,254 564,852 530,877 Purchases of treasury stock: Share repurchase program 31,994 28,949 35,510 Other 592 392 1,018 Dispositions of treasury stock: Shares issued to AFL Stock Plan (1,610) (1,306) (1,782) Exercise of stock options (418) (519) (734) Other (296) (114) (37) Balance, end of period 622,516 592,254 564,852 Shares outstanding, end of period 726,793 755,286 780,910 Outstanding share-based awards are excluded from the calculation of weighted-average shares used in the computation of basic EPS. The following table presents the approximate number of share-based awards to purchase shares, on a weighted-average basis, that were considered to be anti-dilutive and were excluded from the calculation of diluted earnings per share at December 31: (In thousands) 2019 2018 2017 Anti-dilutive share-based awards 6 44 510 The weighted-average shares used in calculating earnings per share for the years ended December 31 were as follows: (In thousands of shares) 2019 2018 2017 Weighted-average outstanding shares used for calculating basic EPS 742,414 769,588 792,042 Dilutive effect of share-based awards 4,016 5,062 5,819 Weighted-average outstanding shares used for calculating diluted EPS 746,430 774,650 797,861 Share Repurchase Program: During 2019 , the Company repurchased 32.0 million shares of its common stock in the open market for $1.6 billion . The Company repurchased 28.9 million shares for $1.3 billion in 2018 and 35.5 million shares for $1.4 billion in 2017 . As of December 31, 2019 , a remaining balance of 37.1 million shares of the Company's common stock was available for purchase under share repurchase authorizations by its board of directors. Voting Rights: In accordance with the Parent Company's articles of incorporation, shares of common stock are generally entitled to one vote per share until they have been held by the same beneficial owner for a continuous period of 48 months , at which time they become entitled to 10 votes per share. Reclassifications from Accumulated Other Comprehensive Income The tables below are reconciliations of accumulated other comprehensive income by component for the years ended December 31. Changes in Accumulated Other Comprehensive Income 2019 (In millions) Unrealized Foreign Unrealized Unrealized Pension Total Balance, beginning of period $ (1,847 ) $ 4,234 $ (24 ) $ (212 ) $ 2,151 Other comprehensive 224 4,327 (9 ) (76 ) 4,466 Amounts reclassified from 0 (13 ) 0 11 (2 ) Net current-period other 224 4,314 (9 ) (65 ) 4,464 Balance, end of period $ (1,623 ) $ 8,548 $ (33 ) $ (277 ) $ 6,615 All amounts in the table above are net of tax. 2018 (In millions) Unrealized Foreign Unrealized Unrealized Pension Liability Adjustment Total Balance, beginning of period $ (1,750 ) $ 5,964 $ (23 ) $ (163 ) $ 4,028 Cumulative effect of change 0 (148 ) 0 0 (148 ) Cumulative effect of change (325 ) 734 (3 ) (32 ) 374 Other comprehensive 228 (2,350 ) 2 (30 ) (2,150 ) Amounts reclassified from 0 34 0 13 47 Net current-period other 228 (2,316 ) 2 (17 ) (2,103 ) Balance, end of period $ (1,847 ) $ 4,234 $ (24 ) $ (212 ) $ 2,151 All amounts in the table above are net of tax. 2017 (In millions) Unrealized Foreign Unrealized Unrealized Pension Liability Adjustment Total Balance, beginning of period $ (1,983 ) $ 4,805 $ (24 ) $ (168 ) $ 2,630 Other comprehensive 233 1,158 1 (6 ) 1,386 Amounts reclassified from 0 1 0 11 12 Net current-period other 233 1,159 1 5 1,398 Balance, end of period $ (1,750 ) $ 5,964 $ (23 ) $ (163 ) $ 4,028 All amounts in the table above are net of tax. For the year ended December 31, 2018, see Note 1 for discussion of the amounts reclassified between AOCI and retained earnings upon the adoption of new accounting pronouncements. The tables below summarize the amounts reclassified from each component of accumulated other comprehensive income based on source for the years ended December 31. Reclassifications Out of Accumulated Other Comprehensive Income (In millions) 2019 Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (13 ) Other-than-temporary impairment 31 Other gains (losses) 18 Total before tax (5 ) Tax (expense) or benefit (1) $ 13 Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (15 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 4 Tax (expense) or benefit (1) $ (11 ) Net of tax Total reclassifications for the period $ 2 Net of tax (1) Based on 26% blended tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 14 for additional details). (In millions) 2018 Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (63 ) Other-than-temporary impairment 17 Other gains (losses) (46 ) Total before tax 12 Tax (expense) or benefit (1) $ (34 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (18 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 5 Tax (expense) or benefit (1) $ (13 ) Net of tax Total reclassifications for the period $ (47 ) Net of tax (1) Based on 27% blended tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 14 for additional details). (In millions) 2017 Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (29 ) Other-than-temporary impairment 27 Other gains (losses) (2 ) Total before tax 1 Tax (expense) or benefit (1) $ (1 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (17 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 6 Tax (expense) or benefit (1) $ (11 ) Net of tax Total reclassifications for the period $ (12 ) Net of tax (1) Based on 35% tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 14 for additional details).

SHARE-BASED COMPENSATION

SHARE-BASED COMPENSATION	12 Months Ended
SHARE-BASED COMPENSATION	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
SHARE-BASED COMPENSATION	SHARE-BASED COMPENSATION As of December 31, 2019 , the Company has outstanding share-based awards under the Aflac Incorporated Long-Term Incentive Plan (the Plan). Share-based awards are designed to reward employees for their long-term contributions to the Company and provide incentives for them to remain with the Company. The number and frequency of share-based awards are based on competitive practices, operating results of the Company, government regulations, and other factors. The Plan, as amended on February 14, 2017, allows for a maximum number of shares issuable over its term of 75 million shares including 38 million shares that may be awarded in respect of awards other than options or stock appreciation rights. If any awards granted under the Plan are forfeited or are terminated before being exercised or settled for any reason other than tax forfeiture, then the shares underlying the awards will again be available under the Plan. The Plan allows awards to Company employees for incentive stock options (ISOs), non-qualifying stock options (NQSOs), restricted stock, restricted stock units, and stock appreciation rights. Non-employee directors are eligible for grants of NQSOs, restricted stock, and stock appreciation rights. As of December 31, 2019 , approximately 39.3 million shares were available for future grants under this plan. The ISOs and NQSOs have a term of 10 years , and the share-based awards generally vest upon time-based conditions or time and performance-based conditions. Time-based vesting generally occurs after three years . Performance-based vesting conditions generally include the attainment of goals related to Company financial performance. As of December 31, 2019 , the only performance-based awards issued and outstanding were restricted stock awards and units. Stock options and stock appreciation rights granted under the amended Plan have an exercise price of at least the fair market value of the underlying stock on the grant date and have an expiration date no later than 10 years from the grant date. Time-based restricted stock awards, restricted stock units and stock options granted after January 1, 2017 generally vest on a ratable basis over three years , and awards granted prior to the amendment vest on a three-year cliff basis. The Compensation Committee of the Board of Directors has the discretion to determine vesting schedules . Share-based awards granted to U.S.-based grantees are settled with authorized but unissued Company stock, while those issued to Japan-based grantees are settled with treasury shares. Summary of Share-Based Compensation Expense Share-based compensation expense consists primarily of expenses for stock options, restricted stock awards (including performance based restricted stock awards), and restricted stock units granted to employees. The following table presents the impact of the expense recognized in connection with share-based awards for the periods ended December 31. (In millions, except for per-share amounts) 2019 2018 2017 Impact on earnings from continuing operations $ 59 $ 57 $ 51 Impact on earnings before income taxes 59 57 51 Impact on net earnings 46 45 35 Impact on net earnings per share: Basic $ .06 $ .06 $ .05 Diluted .06 .06 .05 Stock Options The following table summarizes stock option activity under the employee stock option plan. (In thousands of shares) Stock Weighted-Average Outstanding at December 31, 2016 12,680 $ 26.28 Granted in 2017 626 35.80 Canceled in 2017 (236 ) 24.95 Exercised in 2017 (5,766 ) 30.11 Outstanding at December 31, 2017 7,304 28.03 Granted in 2018 67 44.59 Canceled in 2018 (167 ) 32.11 Exercised in 2018 (1,874 ) 26.78 Outstanding at December 31, 2018 5,330 28.54 Granted in 2019 0 0.00 Canceled in 2019 (40 ) 27.82 Exercised in 2019 (1,584 ) 25.97 Outstanding at December 31, 2019 3,706 $ 29.65 (In thousands of shares) 2019 2018 2017 Shares exercisable, end of year 3,553 3,917 4,208 The Company estimates the fair value of each stock option granted using the Black-Scholes-Merton multiple option approach. Expected volatility is based on historical periods generally commensurate with the estimated terms of the options. The Company uses historical data to estimate option exercise and termination patterns within the model. Separate groups of employees that have similar historical exercise patterns are stratified and considered separately for valuation purposes. The expected term of options granted is derived from the output of the Company's option model and represents the weighted-average period of time that options granted are expected to be outstanding. The Company bases the risk-free interest rate on the Treasury note rate with a term comparable to that of the estimated term of the options. There were no options granted in 2019. The weighted-average fair value of options at their grant date was $8.81 for 2018 compared with $7.64 in 2017 . The following table presents the assumptions used in valuing options granted during the years ended December 31. 2019 2018 2017 Expected term (years) 7.0 7.0 5.9 Expected volatility 18.0 % 22.0 % 26.0 % Annual forfeiture rate 3.9 3.6 3.4 Risk-free interest rate 2.9 2.5 2.5 Dividend yield 2.2 2.4 2.5 The following table summarizes information about stock options outstanding and exercisable at December 31, 2019 . (In thousands of shares) Options Outstanding Options Exercisable Range of Stock Option Wgtd.-Avg. Wgtd.-Avg. Stock Option Wgtd.-Avg. $ 16.92 - $ 24.75 872 2.1 $ 23.58 872 $ 23.58 24.79 - 28.97 919 3.8 28.49 919 28.49 29.04 - 31.21 988 4.7 30.77 988 30.77 31.22 - 36.21 778 6.5 34.31 626 34.02 37.22 - 44.59 149 7.8 40.57 148 40.59 $ 16.92 - $ 44.59 3,706 4.4 $ 29.65 3,553 $ 29.40 The aggregate intrinsic value in the following table represents the total pretax intrinsic value, and is based on the difference between the exercise price of the stock options and the quoted closing common stock price of $52.90 as of December 31, 2019 , for those awards that have an exercise price currently below the closing price. As of December 31, 2019 , the aggregate intrinsic value of stock options outstanding was $86 million , with a weighted-average remaining term of 4.4 years . The total number of in-the-money stock options exercisable as of December 31, 2019 , was 3.6 million . The aggregate intrinsic value of stock options exercisable at that same date was $84 million , with a weighted-average remaining term of 4.2 years . The following table summarizes stock option activity during the years ended December 31. (In millions) 2019 2018 2017 Total intrinsic value of options exercised $ 38 $ 34 $ 87 Cash received from options exercised 40 48 58 Tax benefit realized as a result of options exercised and 34 25 74 Performance-Based Restricted Stock Awards and Units Under the Plan, the Company grants selected executive officers performance-based restricted stock awards (PBRS) each February whose vesting is contingent upon meeting various performance goals. PBRS are generally granted at-the-money and contingently cliff vest over a period of three years , generally subject to continued employment. In February 2019, the Company granted 399 thousand performance-based stock awards, which are contingent on the achievement of the Company's financial performance metrics and its market-based conditions. On the date of grant, the Company estimated the fair value of restricted stock awards with market-based conditions using a Monte Carlo simulation model. The model discounts the value of the stock at the assumed vesting date based on a risk-free interest rate. Based on estimates of actual performance versus the vesting thresholds, the calculated fair value percentage pay-out estimate will be updated each quarter. Actual performance, including modification for relative total shareholder return, may result in the ultimate award of 0% to 200% percent of the initial number of PBRS issued, with the potential for no award if company performance goals are not achieved during the three-year period. PBRS subject to accelerated vesting at the date of retirement eligibility is recognized over the implicit service period. The Company also granted selected executive officers performance-based restricted stock units (PSUs) throughout the year whose vesting is contingent upon meeting various performance goals. PSUs are generally granted at-the-money and contingently cliff vest over a period of three years , generally subject to continued employment. In November 2019, the Company granted 46 thousand performance-based stock units, which are contingent on the achievement of certain Company determined metrics. Based on estimates of actual performance versus the vesting thresholds, the calculated fair value percentage pay-out estimate will be updated each quarter. Actual performance may result in the ultimate award of 0% to 200% percent of the initial number of PSUs issued, with the potential for no award if the Company determined metrics are not achieved during the three-year period. PSUs subject to accelerated vesting at the date of retirement eligibility is recognized over the implicit service period. The Company uses third-party analyses to assist in developing the assumptions used in, as well as calibrating, a Monte Carlo simulation model. The Company is responsible for determining the assumptions used in estimating the fair value of its share-based payment awards. Key assumptions used to value PBRS granted during 2019 follows: (In millions) 2019 Expected volatility (based on Aflac Inc. and peer group historical daily stock price) 15.82 % Expected life from grant date (years) 2.9 Risk-free interest rate (based on U.S. Treasury yields at the date of grant) 2.51 % Restricted Stock Awards and Units The value of restricted stock awards and restricted stock units is based on the fair market value of the Company's common stock at the date of grant. The following table summarizes restricted stock activity during the years ended December 31. (In thousands of shares) Shares Weighted-Average Restricted stock at December 31, 2016 3,736 $ 30.88 Granted in 2017 1,118 36.48 Canceled in 2017 (202 ) 32.23 Vested in 2017 (1,018 ) 31.09 Restricted stock at December 31, 2017 3,634 32.40 Granted in 2018 1,121 44.27 Canceled in 2018 (105 ) 34.39 Vested in 2018 (1,243 ) 31.64 Restricted stock at December 31, 2018 3,407 36.52 Granted in 2019 1,070 49.68 Canceled in 2019 (39 ) 41.60 Vested in 2019 (1,865 ) 32.73 Restricted stock at December 31, 2019 2,573 $ 44.66 As of December 31, 2019 , total compensation cost not yet recognized in the Company's financial statements related to restricted stock awards and restricted stock units was $60 million , of which $30 million ( 1.5 million shares) was related to restricted stock awards with a performance-based vesting condition. The Company expects to recognize these amounts over a weighted-average period of approximately 1.1 years . There are no other contractual terms covering restricted stock awards once vested.

STATUTORY ACCOUNTING AND DIVIDE

STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS	12 Months Ended
STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS	Dec. 31, 2019
Insurance [Abstract]
STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS	STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS The Company's insurance subsidiaries are required to report their results of operations and financial position to insurance regulatory authorities on the basis of statutory accounting practices prescribed or permitted by such authorities. Statutory accounting practices primarily differ from U.S. GAAP by charging policy acquisition costs to expense as incurred, establishing future policy benefit liabilities using different actuarial assumptions as well as valuing investments and certain assets and accounting for deferred taxes on a different basis. Aflac reports statutory financial statements that are prepared on the basis of accounting practices prescribed or permitted by the Nebraska Department of Insurance (NDOI). The NDOI recognizes statutory accounting principles and practices prescribed or permitted by the state of Nebraska for determining and reporting the financial condition and results of operations of an insurance company, and for determining a company's solvency under Nebraska insurance law. Statutory Accounting Principles (SAP) as detailed by the National Association of Insurance Commissioners' (NAIC) Accounting Practices and Procedures Manual has been adopted by the state of Nebraska as a component of those prescribed or permitted practices. Additionally, the Director of the NDOI has the right to permit other specific practices which deviate from prescribed practices. Prior to the Japan branch conversion on April 1, 2018, Aflac had been given explicit permission by the Director of the NDOI for two such permitted practices. On April 1, 2018, the Company entered into a series of transactions in order to complete the conversion of the Japan branch into a Japanese insurance corporation. As a result of the conversion, the permitted practices were no longer necessary, therefore they were canceled by the NDOI effective April 2, 2018. Aflac had no permitted practices as of December 31, 2019 and 2018 . Aflac's capital and surplus as determined by NAIC basis and Nebraska state basis was $2.1 billion and $2.6 billion as of December 31, 2019 and 2018 , respectively. As of December 31, 2019 , Aflac's capital and surplus significantly exceeded the required company action level capital and surplus of $.4 billion . As determined on a U.S. statutory accounting basis, Aflac's net income was $864 million in 2019 , $1.3 billion in 2018 and $2.6 billion in 2017 . Aflac Japan must report its results of operations and financial position to the Japanese Financial Services Agency (FSA) on a Japanese regulatory accounting basis as prescribed by the FSA. Capital and surplus of Aflac Japan, based on Japanese regulatory accounting practices, was $7.8 billion at December 31, 2019 , compared with $6.4 billion at December 31, 2018 . Japanese regulatory accounting practices differ in many respects from U.S. GAAP. Under Japanese regulatory accounting practices, policy acquisition costs are expensed immediately; policy benefit and claim reserving methods and assumptions are different; premium income is recognized on a cash basis; different consolidation criteria apply to VIEs; reinsurance is recognized on a different basis; and investments can have a separate accounting classification and treatment referred to as policy reserve matching bonds (PRM). The Parent Company depends on its subsidiaries for cash flow, primarily in the form of dividends and management fees. Consolidated retained earnings in the accompanying financial statements largely represent the undistributed earnings of the Company's insurance subsidiary. Amounts available for dividends, management fees and other payments to the Parent Company by its insurance subsidiaries may fluctuate due to different accounting methods required by regulatory authorities. These payments are also subject to various regulatory restrictions and approvals related to safeguarding the interests of insurance policyholders. Aflac must maintain adequate RBC for U.S. regulatory authorities, and Aflac Japan must maintain adequate solvency margins for Japanese regulatory authorities. The maximum amount of dividends that can be paid to the Parent Company by Aflac and CAIC without prior approval of Nebraska's director of insurance is the greater of the net income from operations, which excludes net realized investment gains, for the previous year determined under statutory accounting principles, or 10% of statutory capital and surplus as of the previous year-end. Dividends declared by Aflac during 2020 in excess of $864 million would require such approval. Aflac declared dividends of $1.3 billion during 2019 . After the Japan branch conversion as of April 1, 2018, Aflac Japan is required to meet certain financial criteria as governed by Japanese corporate law in order to provide dividends to the Parent Company. Under these criteria, dividend capacity at Aflac Japan is basically defined as retained earnings excluding capital reserves, which represent equity generated by capital profits that are statutorily required in Japan, less net after-tax unrealized losses on available-for-sale securities based on the previous fiscal year-end. Prior to April 1, 2018, a portion of Aflac Japan earnings, as determined on a Japanese regulatory accounting basis, could be remitted each year to Aflac U.S. after complying with solvency margin provisions and satisfying various conditions imposed by Japanese regulatory authorities for protecting policyholders. Profit remittances to the U.S. could fluctuate due to changes in the amounts of Japanese regulatory earnings. Among other items, factors affecting regulatory earnings include Japanese regulatory accounting practices and fluctuations in currency translation of Aflac Japan's U.S. dollar-denominated investments and related investment income into yen. Profits remitted by Aflac Japan to the Parent Company, after April 1, 2018, and to Aflac U.S., prior to April 1, 2018, were as follows for the years ended December 31: In Dollars In Yen (In millions of dollars and billions of yen) 2019 2018 2017 2019 2018 2017 Profit remittances $ 2,070 $ 808 $ 1,150 ¥ 225.2 ¥ 89.7 ¥ 129.3

BENEFIT PLANS

BENEFIT PLANS	12 Months Ended
BENEFIT PLANS	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
BENEFIT PLANS	Pension and Other Postretirement Plans The Company has funded defined benefit plans in Japan and the U.S., however the U.S. plan was frozen to new participants effective October 1, 2013. The Company also maintains non-qualified, unfunded supplemental retirement plans that provide defined pension benefits in excess of limits imposed by federal tax law for certain Japanese, U.S. and former employees, however the U.S. plan was frozen to new participants effective January 1, 2015. U.S. employees who are not participants in the defined benefit plan receive a nonelective 401(k) employer contribution. The Company provides certain health care benefits for eligible U.S. retired employees, their beneficiaries and covered dependents (other postretirement benefits). The health care plan is contributory and unfunded. Effective January 1, 2014, employees eligible for benefits included the following: (1) active employees whose age plus service, in years, equaled or exceeded 80 (rule of 80 ); (2) active employees who were age 55 or older and have met the 15 years of service requirement; (3) active employees who would meet the rule of 80 in the next five years ; (4) active employees who were age 55 or older and who would meet the 15 years of service requirement within the next five years ; and (5) current retirees. For certain employees and former employees, additional coverage is provided for all medical expenses for life. Information with respect to the Company's benefit plans' assets and obligations as of December 31 was as follows: Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2019 2018 2019 2018 2019 2018 Projected benefit obligation: Benefit obligation, beginning of year $ 396 $ 341 $ 875 $ 908 $ 37 $ 36 Service cost 22 19 23 27 0 0 Interest cost 7 7 20 31 1 1 Actuarial (gain) loss 17 35 163 (3) (69 ) 4 4 Benefits and expenses paid (11 ) (11 ) (23 ) (22 ) (3 ) (4 ) Effect of foreign exchange 5 5 0 0 0 0 Benefit obligation, end of year 436 396 1,058 875 39 37 Plan assets: Fair value of plan assets, 289 270 465 448 0 0 Actual return on plan assets 24 (9 ) 98 (30 ) 0 0 Employer contributions 38 34 104 69 3 4 Benefits and expenses paid (11 ) (11 ) (23 ) (22 ) (3 ) (4 ) Effect of foreign exchange 4 5 0 0 0 0 Fair value of plan assets, 344 289 644 465 0 0 Funded status of the plans (1) $ (92 ) $ (107 ) $ (414 ) $ (410 ) $ (39 ) $ (37 ) Amounts recognized in accumulated other Net actuarial (gain) loss $ 92 $ 95 $ 259 $ 174 $ 12 $ 9 Prior service (credit) cost (2 ) (2 ) (4 ) (4 ) 0 0 Total included in accumulated $ 90 $ 93 $ 255 $ 170 $ 12 $ 9 Accumulated benefit obligation $ 390 $ 356 $ 886 $ 746 N/A (2) N/A (2) (1) Recognized in other liabilities in the consolidated balance sheets (2) Not applicable (3) Actuarial losses increased due to lower discount rates at the end of 2019. Also, additional funds were contributed to the U.S. funded defined benefit plan in 2019. The Company contributed $95 million in 2019 compared to $60 million in 2018. Information for Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets Pension Benefits Japan U.S. (In millions) 2019 2018 2019 2018 Accumulated benefit obligation $ 390 $ 356 $ 886 $ 746 Fair value of plan assets 344 289 644 465 Information for Pension Plans with a Projected Benefit Obligation in Excess of Plan Assets Pension Benefits Japan (1) U.S. (2) (In millions) 2019 2018 2019 2018 Projected benefit obligation $ 436 $ 396 $ 1,058 $ 875 Fair value of plan assets 344 289 644 465 (1) The net amount of projected benefit obligation and plan assets for the underfunded (including unfunded) Japan pension plan was $92 and $107 at December 31, 2019 and 2018, respectively, and was classified as liabilities on the statement of financial position. (2) The net amount of projected benefit obligation and plan assets for the underfunded (including unfunded) U.S. pension plan was $414 and $410 at December 31, 2019 and 2018, respectively, and was classified as liabilities on the statement of financial position. Information for other postretirement benefit plans with an accumulated postretirement benefit obligation in excess of plan assets has been disclosed in the note on “Obligations and Funded Status” because all the other postretirement benefit plans are unfunded or underfunded. Pension Benefits Other Japan U.S. Postretirement Benefits 2019 2018 2017 2019 2018 2017 2019 2018 2017 Weighted-average actuarial assumptions: Discount rate - net periodic benefit cost 1.25 % 1.25 % 1.25 % 4.25 % 3.75 % 4.25 % 4.25 % 3.75 % 4.25 % Discount rate - benefit obligations .75 1.25 1.25 3.25 4.25 3.75 3.25 4.25 3.75 Expected long-term return on plan assets 2.00 2.00 2.00 6.25 6.50 6.75 N/A (1) N/A (1) N/A (1) Rate of compensation increase N/A (1) N/A (1) N/A (1) 4.00 4.00 4.00 N/A (1) N/A (1) N/A (1) Health care cost trend rates N/A (1) N/A (1) N/A (1) N/A (1) N/A N/A (1) 7.50 (2) 7.40 (2) 5.40 (2) (1) Not applicable (2) For the years 2019 , 2018 and 2017 , the health care cost trend rates are expected to trend down to 3.8% in 54 years , 4.1% in 61 years , and 4.5% in 77 years , respectively. The Company determines its discount rate assumption for its pension retirement obligations based on indices for AA corporate bonds with an average duration of approximately 20 years for the Japan pension plans and 17 years for the U.S. pension plans, and determination of the U.S. pension plans discount rate utilizes the 85 -year extrapolated yield curve. In Japan, participant salary and future salary increases are not factors in determining pension benefit cost or the related pension benefit obligation. The Company bases its assumption for the long-term rate of return on assets on historical trends ( 10 -year or longer historical rates of return for the Japanese plan assets and 15 -year historical rates of return for the U.S. plan assets), expected future market movement, as well as the portfolio mix of securities in the asset portfolio including, but not limited to, style, class and equity and fixed income allocations. In addition, the Company's consulting actuaries evaluate its assumptions for long-term rates of return under Actuarial Standards of Practice (ASOP). Under the ASOP, the actual portfolio type, mix and class is modeled to determine a best estimate of the long-term rate of return. The Company in turn use those results to further validate its own assumptions. Components of Net Periodic Benefit Cost Pension and other postretirement benefit expenses are included in acquisition and operating expenses in the consolidated statements of earnings, which includes $8 million , $25 million and $35 million of other components of net periodic pension cost and postretirement costs (other than services costs) for the years ended December 31, 2019, 2018 and 2017, respectively. Total net periodic benefit cost includes the following components: Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2019 2018 2017 2019 2018 2017 2019 2018 2017 Service cost $ 22 $ 19 $ 20 $ 23 $ 27 $ 24 $ 0 $ 0 $ 0 Interest cost 7 7 6 20 31 40 1 1 1 Expected return on plan (6 ) (6 ) (5 ) (29 ) (26 ) (24 ) 0 0 0 Amortization of net actuarial 4 1 2 10 16 14 1 1 1 Net periodic (benefit) cost $ 27 $ 21 $ 23 $ 24 $ 48 $ 54 $ 2 $ 2 $ 2 Changes in Accumulated Other Comprehensive Income The following table summarizes the amounts recognized in other comprehensive loss (income) for the years ended December 31: Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2019 2018 2017 2019 2018 2017 2019 2018 2017 Net actuarial loss (gain) $ 1 $ 52 $ (21 ) $ 95 $ (13 ) $ 28 $ 4 $ 4 $ 0 Amortization of net actuarial loss (4 ) (1 ) (2 ) (10 ) (16 ) (14 ) (1 ) (1 ) (1 ) Total $ (3 ) $ 51 $ (23 ) $ 85 $ (29 ) $ 14 $ 3 $ 3 $ (1 ) No transition obligations arose during 2019 . Benefit Payments The following table provides expected benefit payments, which reflect expected future service, as appropriate. Pension Benefits Other (In millions) Japan U.S. Postretirement Benefits 2020 $ 13 $ 25 $ 3 2021 12 27 4 2022 17 29 4 2023 14 30 4 2024 16 31 4 2025-2029 84 203 16 Funding The Company plans to make contributions of $35 million to the Japanese funded defined benefit plan in 2020. The Company does not plan to make any contributions to the U.S. funded defined benefit plan in 2020 . The Company funded additional contributions to the U.S. funded defined benefit plan in 2019. The funding policy for the Company's non-qualified supplemental defined benefit pension plans and other postretirement benefits plan is to contribute the amount of the benefit payments made during the year. Plan Assets The investment objective of the Company's Japanese and U.S. funded defined benefit plans is to preserve the purchasing power of the plan's assets and earn a reasonable inflation-adjusted rate of return over the long term. Furthermore, the Company seeks to accomplish these objectives in a manner that allows for the adequate funding of plan benefits and expenses. In order to achieve these objectives, the Company's goal is to maintain a conservative, well-diversified and balanced portfolio of high-quality equity, fixed-income and money market securities. As a part of its strategy, the Company has established strict policies covering quality, type and concentration of investment securities. For the Company's Japanese plan, these policies include limitations on investments in derivatives including futures, options and swaps, and low-liquidity investments such as real estate, venture capital investments, and privately issued securities. For the Company's U.S. plan, these policies prohibit investments in precious metals, limited partnerships, venture capital, and direct investments in real estate. The Company is also prohibited from trading on margin. The plan fiduciaries for the Company's funded defined benefit plans have developed guidelines for asset allocations reflecting a percentage of total assets by asset class, which are reviewed on an annual basis. Asset allocation targets as of December 31, 2019 were as follows: Japan Pension U.S. Pension Domestic equities 5 % 40 % International equities 20 20 Fixed income securities 66 40 Other 9 0 Total 100 % 100 % The U.S. Pension Plan had $100 million in cash at December 31, 2019. The plan fiduciaries authorized investing a contribution made to the Plan in 2019 on a graduated basis over a period of time. The following table presents the fair value of Aflac Japan's pension plan assets that are measured at fair value on a recurring basis as of December 31. All of these assets are classified as Level 2 in the fair value hierarchy. (In millions) 2019 2018 Japan pension plan assets: Equities: Japanese equity securities $ 17 $ 14 International equity securities 67 50 Fixed income securities: Japanese bonds 20 34 International bonds 207 160 Insurance contracts 33 31 Total $ 344 $ 289 The following table presents the fair value of Aflac U.S.'s pension plan assets that are measured at fair value on a recurring basis as of December 31. All of these assets are classified as Level 1 in the fair value hierarchy. (In millions) 2019 2018 U.S. pension plan assets: Mutual funds: Large cap equity funds $ 179 $ 120 Mid cap equity funds 22 17 Real estate equity funds 16 13 International equity funds 112 92 Fixed income bond funds 209 179 Aflac Incorporated common stock 6 5 Cash and cash equivalents 100 39 Total $ 644 $ 465 The fair values of the Company's pension plan investments categorized as Level 1, consisting of mutual funds and common stock, are based on quoted market prices for identical securities traded in active markets that are readily and regularly available to the Company. The fair values of the Company's pension plan investments classified as Level 2 are based on quoted prices for similar assets in markets that are not active, other inputs that are observable, such as interest rates, yield curves, volatilities, prepayment speeds, loss severities, credit risks, and default rates, or other market-corroborated inputs. 401(k) Plan The Company sponsors a 401(k) plan in which it matches a portion of U.S. employees' contributions. The plan provides for salary reduction contributions by employees and provides for matching contributions which, starting January 1, 2018, the Company increased to 100% of each employee's contributions which were not in excess of 4% of the employee's annual cash compensation as a result of tax reform. The Company also provides a nonelective contribution to the 401(k) plan of 2% of annual cash compensation for employees who opted out of the future benefits of the U.S. defined benefit plan and for new U.S. employees. The 401(k) contributions by the Company, included in acquisition and operating expenses in the consolidated statements of earnings, were $18 million in both 2019 and 2018 and $15 million in 2017 . The plan trustee held approximately 2.6 million shares of the Company's common stock for plan participants at December 31, 2019 . Stock Bonus Plan Aflac U.S. maintains a stock bonus plan for eligible U.S. sales associates. Plan participants receive shares of Aflac Incorporated common stock based on their new annualized premium sales and their first-year persistency of substantially all new insurance policies. The cost of this plan, which was capitalized as deferred policy acquisition costs, amounted to $31 million in 2019 , 2018 and 2017 .

COMMITMENTS AND CONTINGENT LIAB

COMMITMENTS AND CONTINGENT LIABILITIES	12 Months Ended
COMMITMENTS AND CONTINGENT LIABILITIES	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENT LIABILITIES	COMMITMENTS AND CONTINGENT LIABILITIES The Company has two outsourcing agreements with a technology and consulting corporation. The first agreement provides mainframe computer operations, distributed mid-range server computer operations, and related support for Aflac Japan. It has a remaining term of three years and an aggregate remaining cost of ¥26.7 billion ( $244 million using the December 31, 2019 , exchange rate). The second agreement provides application maintenance and development services for Aflac Japan. It has a remaining term of four years and an aggregate remaining cost of ¥6.6 billion ( $61 million using the December 31, 2019 , exchange rate). The Company has an outsourcing agreement with a management consulting and technology services company to provide application maintenance and development services for its Japanese operation. The agreement has a remaining term of two years with an aggregate remaining cost of ¥6.9 billion ( $63 million using the December 31, 2019 , exchange rate). The Company has two outsourcing agreements with information technology and data services companies to provide application maintenance and development services for its Japanese operation. The first agreement has a remaining term of three years with an aggregate remaining cost of ¥5.5 billion ( $50 million using the December 31, 2019 , exchange rate). The second agreement has a remaining term of three years with an aggregate remaining cost of ¥4.9 billion ( $45 million using the December 31, 2019 , exchange rate). The Company is a defendant in various lawsuits considered to be in the normal course of business. Members of the Company's senior legal and financial management teams review litigation on a quarterly and annual basis. The final results of any litigation cannot be predicted with certainty. Although some of this litigation is pending in states where large punitive damages, bearing little relation to the actual damages sustained by plaintiffs, have been awarded in recent years, the Company believes the outcome of pending litigation will not have a material adverse effect on its financial position, results of operations, or cash flows. See Note 3 of the Notes to the Consolidated Financial Statements for details on certain investment commitments. Guaranty Fund Assessments The U.S. insurance industry has a policyholder protection system that is monitored and regulated by state insurance departments. These life and health insurance guaranty associations are state entities (in all 50 states as well as Puerto Rico and the District of Columbia) created to protect policyholders of an insolvent insurance company. All insurance companies (with limited exceptions) licensed to sell life or health insurance in a state must be members of that state’s guaranty association. Under state guaranty association laws, certain insurance companies can be assessed (up to prescribed limits) for certain obligations to the policyholders and claimants of impaired or insolvent insurance companies that write the same line or similar lines of business. In 2009, the Pennsylvania Insurance Commissioner placed long-term care insurer Penn Treaty Network America Insurance Company and its subsidiary American Network Insurance Company (collectively referred to as Penn Treaty), neither of which is affiliated with Aflac, in rehabilitation and petitioned a state court for approval to liquidate Penn Treaty. A final order of liquidation was granted by a recognized judicial authority on March 1, 2017, and as a result, Penn Treaty is in the process of liquidation. The Company estimated and recognized the impact of its share of guaranty fund assessments resulting from the liquidation using a discounted rate of 4.25% . The Company recognized a discounted liability for the assessments of $62 million (undiscounted $94 million ), offset by discounted premium tax credits of $48 million (undiscounted $74 million ), for a net $14 million impact to net income in the quarter ended March 31, 2017. The Company paid a majority of these assessments by March 31, 2019. The Company used the cost estimate provided as of the liquidation date by the National Organization of Life and Health Guaranty Associations (NOLHGA) to calculate its estimated assessments and tax credits. Other guaranty fund assessments for the years ended December 31, 2019, 2018, and 2017 were immaterial.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
SUBSEQUENT EVENTS	Dec. 31, 2019
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS In January 2020, the Parent Company used proceeds from senior notes issued in December 2019 to redeem $350 million of its 4.00% fixed-rate senior notes due February 2022.

UNAUDITED CONSOLIDATED QUARTERL

UNAUDITED CONSOLIDATED QUARTERLY FINANCIAL DATA	12 Months Ended
UNAUDITED CONSOLIDATED QUARTERLY FINANCIAL DATA	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
UNAUDITED CONSOLIDATED QUARTERLY FINANCIAL DATA	UNAUDITED CONSOLIDATED QUARTERLY FINANCIAL DATA In management's opinion, the following quarterly financial information fairly presents the results of operations for such periods and is prepared on a basis consistent with the Company's annual audited financial statements. (In millions, except for per-share amounts) March 31, June 30, September 30, December 31, Net premium income $ 4,691 $ 4,681 $ 4,736 $ 4,671 Net investment income 878 878 936 886 Realized investment gains (losses) 71 (66 ) (153 ) 12 Other income (loss) 17 18 17 34 Total revenues 5,657 5,511 5,536 5,603 Total benefits and expenses 4,415 4,402 4,500 4,545 Earnings before income taxes 1,242 1,109 1,036 1,058 Total income tax 314 292 259 276 Net earnings $ 928 $ 817 $ 777 $ 782 Net earnings per basic share $ 1.23 $ 1.10 $ 1.05 $ 1.07 Net earnings per diluted share 1.23 1.09 1.04 1.06 Quarterly amounts may not agree in total to the corresponding annual amounts due to rounding. (In millions, except for per-share amounts) March 31, June 30, September 30, December 31, Net premium income $ 4,745 $ 4,706 $ 4,636 $ 4,591 Net investment income 837 862 870 874 Realized investment gains (losses) (134 ) 3 56 (355 ) Other income (loss) 16 18 15 16 Total revenues 5,464 5,589 5,577 5,126 Total benefits and expenses 4,482 4,458 4,431 4,404 Earnings before income taxes 982 1,131 1,146 722 Total income tax 265 299 301 197 Net earnings $ 717 $ 832 $ 845 $ 525 Net earnings per basic share $ .92 $ 1.08 $ 1.10 $ .69 Net earnings per diluted share .91 1.07 1.09 .69 Quarterly amounts may not agree in total to the corresponding annual amounts due to rounding.

SCHEDULE II CONDENSED FINANCIAL

SCHEDULE II CONDENSED FINANCIAL INFORMATION OF REGISTRANT	12 Months Ended
SCHEDULE II CONDENSED FINANCIAL INFORMATION OF REGISTRANT	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
SCHEDULE II CONDENSED FINANCIAL INFORMATION OF REGISTRANT	CONDENSED FINANCIAL INFORMATION OF REGISTRANT Aflac Incorporated (Parent Only) Condensed Statements of Earnings Years ended December 31, (In millions) 2019 2018 2017 Revenues: Management and service fees from subsidiaries (1) $ 151 $ 190 $ 297 Net investment income 77 69 30 Interest from subsidiaries (1) 4 4 5 Realized investment gains (losses) 98 (16 ) (1 ) Total revenues 330 247 331 Operating expenses: Interest expense 200 188 197 Other operating expenses (2) 221 225 180 Total operating expenses 421 413 377 Earnings before income taxes and equity in earnings of (91 ) (166 ) (46 ) Income tax expense (benefit) (22 ) (12 ) (23 ) Earnings before equity in earnings of subsidiaries (69 ) (154 ) (23 ) Equity in earnings of subsidiaries (1) 3,373 3,074 4,627 Net earnings $ 3,304 $ 2,920 $ 4,604 (1) Eliminated in consolidation (2) Includes expense of $13 in 2017 for the early extinguishment of debt See the accompanying Notes to Condensed Financial Statements. See the accompanying Report of Independent Registered Public Accounting Firm. CONDENSED FINANCIAL INFORMATION OF REGISTRANT Aflac Incorporated (Parent Only) Condensed Statements of Comprehensive Income (Loss) Years ended December 31, (In millions) 2019 2018 2017 Net earnings $ 3,304 $ 2,920 $ 4,604 Other comprehensive income (loss) before income taxes: Unrealized foreign currency translation gains (losses) during period 252 232 286 Unrealized gains (losses) on fixed maturity securities during period 5,852 (3,109 ) 1,733 Unrealized gains (losses) on derivatives during period (12 ) 2 1 Pension liability adjustment during period (85 ) (25 ) 9 Total other comprehensive income (loss) before income taxes 6,007 (2,900 ) 2,029 Income tax expense (benefit) related to items of other comprehensive 1,543 (797 ) 631 Other comprehensive income (loss), net of income taxes 4,464 (2,103 ) 1,398 Total comprehensive income (loss) $ 7,768 $ 817 $ 6,002 See the accompanying Notes to Condensed Financial Statements. See the accompanying Report of Independent Registered Public Accounting Firm. CONDENSED FINANCIAL INFORMATION OF REGISTRANT Aflac Incorporated (Parent Only) Condensed Balance Sheets December 31, (In millions, except for share and per-share amounts) 2019 2018 Assets: Investments and cash: Fixed maturity securities available for sale, at fair value $ 1,567 $ 1,222 Investments in subsidiaries (1) 30,744 26,230 Other investments 36 21 Cash and cash equivalents 2,508 1,767 Total investments and cash 34,855 29,240 Due from subsidiaries (1) 170 98 Income taxes receivable 337 176 Other assets 405 390 Total assets $ 35,767 $ 29,904 Liabilities and shareholders' equity: Liabilities: Employee benefit plans $ 323 $ 310 Notes payable 6,136 5,765 Other liabilities 349 367 Total liabilities 6,808 6,442 Shareholders' equity: Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2019 and 2018; issued 1,349,309 shares in 2019 and 1,347,540 shares in 2018 135 135 Additional paid-in capital 2,313 2,177 Retained earnings 34,291 31,788 Accumulated other comprehensive income (loss): Unrealized foreign currency translation gains (losses) (1,623 ) (1,847 ) Unrealized gains (losses) on fixed maturity securities 8,548 4,234 Unrealized gains (losses) on derivatives (33 ) (24 ) Pension liability adjustment (277 ) (212 ) Treasury stock, at average cost (14,395 ) (12,789 ) Total shareholders' equity 28,959 23,462 Total liabilities and shareholders' equity $ 35,767 $ 29,904 (1) Eliminated in consolidation See the accompanying Notes to Condensed Financial Statements. See the accompanying Report of Independent Registered Public Accounting Firm. CONDENSED FINANCIAL INFORMATION OF REGISTRANT Aflac Incorporated (Parent Only) Condensed Statements of Cash Flows Years ended December 31, (In millions) 2019 2018 2017 Cash flows from operating activities: Net earnings $ 3,304 $ 2,920 $ 4,604 Adjustments to reconcile net earnings to net cash provided from Equity in earnings of subsidiaries (1) (3,373 ) (3,074 ) (4,627 ) Cash dividends received from subsidiaries 3,466 1,820 2,001 Other, net (203 ) 99 (46 ) Net cash provided (used) by operating activities 3,194 1,765 1,932 Cash flows from investing activities: Fixed maturity securities sold 340 207 263 Fixed maturity securities purchased (639 ) (254 ) (329 ) Other investments sold (purchased) (16 ) 31 (47 ) Settlement of derivatives 22 (2 ) 223 Additional capitalization of subsidiaries (1) (214 ) (62 ) (69 ) Other, net 87 (107 ) (218 ) Net cash provided (used) by investing activities (420 ) (187 ) (177 ) Cash flows from financing activities: Purchases of treasury stock (1,627 ) (1,301 ) (1,351 ) Proceeds from borrowings 347 1,020 1,040 Principal payments under debt obligations 0 (550 ) (1,161 ) Dividends paid to shareholders (771 ) (793 ) (661 ) Treasury stock reissued 49 58 33 Proceeds from exercise of stock options 29 34 38 Net change in amount due to/from subsidiaries (1) (58 ) (4 ) (5 ) Other, net (2 ) 0 0 Net cash provided (used) by financing activities (2,033 ) (1,536 ) (2,067 ) Net change in cash and cash equivalents 741 42 (312 ) Cash and cash equivalents, beginning of period 1,767 1,725 2,037 Cash and cash equivalents, end of period $ 2,508 $ 1,767 $ 1,725 (1) Eliminated in consolidation See the accompanying Notes to Condensed Financial Statements. See the accompanying Report of Independent Registered Public Accounting Firm. (A) Notes Payable A summary of notes payable as of December 31 follows: (In millions) 2019 2018 4.00% senior notes due February 2022 (1) $ 348 $ 348 3.625% senior notes due June 2023 698 698 3.625% senior notes due November 2024 747 746 3.25% senior notes due March 2025 448 447 2.875% senior notes due October 2026 298 297 6.90% senior notes due December 2039 220 220 6.45% senior notes due August 2040 254 254 4.00% senior notes due October 2046 394 394 4.750% senior notes due January 2049 541 540 Yen-denominated senior notes and subordinated debentures: .932% senior notes due January 2027 (principal amount ¥60.0 billion) 545 538 .500% senior notes due December 2029 (principal amount ¥12.6 billion) 114 0 1.159% senior notes due October 2030 (principal amount ¥29.3 billion) 266 262 .843% senior notes due December 2031 (principal amount ¥9.3 billion) 84 0 1.488% senior notes due October 2033 (principal amount ¥15.2 billion) 138 136 .934% senior notes due December 2034 (principal amount ¥9.8 billion) 88 0 1.750% senior notes due October 2038 (principal amount ¥8.9 billion) 81 79 1.122% senior notes due December 2039 (principal amount ¥6.3 billion) 57 0 2.108% subordinated debentures due October 2047 (principal amount ¥60.0 billion) 543 536 Yen-denominated loans: Variable interest rate loan due September 2026 (.42% in 2019 and .32 in 2018, principal amount ¥5.0 billion) 45 45 Variable interest rate loan due September 2029 (.57% in 2019 and .47 in 2018, principal amount ¥25.0 billion) 227 225 Total notes payable $ 6,136 $ 5,765 (1) Redeemed in January 2020 Amounts in the table above are reported net of debt issuance costs and issuance premiums or discounts, if applicable, that are being amortized over the life of the notes. In December 2019, the Parent Company issued four series of senior notes totaling ¥38.0 billion through a public debt offering under its U.S. shelf registration statement. The first series, which totaled ¥12.6 billion , bears interest at a fixed rate of .500% per annum, payable semi-annually, and will mature in December 2029. The second series, which totaled ¥9.3 billion , bears interest at a fixed rate of .843% per annum, payable semi-annually, and will mature in December 2031. The third series, which totaled ¥9.8 billion , bears interest at a fixed rate of .934% per annum, payable semi-annually, and will mature in December 2034. The fourth series, which totaled ¥6.3 billion , bears interest at a fixed rate of 1.122% per annum, payable semi-annually, and will mature in December 2039. These notes may only be redeemed before maturity, in whole but not in part, upon the occurrence of certain changes affecting U.S. taxation, as specified in the indenture governing the terms of the issuance. In September 2019, the Parent Company renewed a ¥30.0 billion senior term loan facility. The first tranche of the facility, which totaled ¥5.0 billion , bears interest at a rate per annum equal to the Tokyo interbank market rate (TIBOR), or alternate TIBOR, if applicable, plus the applicable TIBOR margin and will mature in September 2026. The applicable margin ranges between .30% and .70% , depending on the Parent Company's debt ratings as of the date of determination. The second tranche, which totaled ¥25.0 billion , bears interest at a rate per annum equal to the TIBOR, or alternate TIBOR, if applicable, plus the applicable TIBOR margin and will mature in September 2029. The applicable margin ranges between .45% and 1.00% , depending on the Parent Company's debt ratings as of the date of determination. The aggregate contractual maturities of notes payable during each of the years after December 31, 2019 , are as follows: (In millions) 2020 $ 0 2021 0 2022 350 2023 700 2024 750 Thereafter 4,386 Total $ 6,186 For further information regarding notes payable, see Note 9 of the Notes to the Consolidated Financial Statements. (B) Derivatives At December 31, 2019 , the Parent Company's outstanding freestanding derivative contracts were swaps, foreign currency forwards and options. The swaps are associated with its notes payable, consisting of cross-currency interest rate swaps, also referred to as foreign currency swaps, associated with the Parent Company's senior notes due in February 2022, June 2023, November 2024 and March 2025. The foreign currency forwards and options are designated as derivative hedges of the foreign currency exposure of the Company's net investment in Aflac Japan. The Parent Company does not use derivative financial instruments for trading purposes, nor does it engage in leveraged derivative transactions. For further information regarding these derivatives, see Notes 1, 4 and 9 of the Notes to the Consolidated Financial Statements. (C) Income Taxes The Parent Company and its eligible U.S. subsidiaries file a consolidated U.S. federal income tax return. Income tax liabilities or benefits are recorded by each principal subsidiary based upon separate return calculations, and any difference between the consolidated provision and the aggregate amounts recorded by the subsidiaries is reflected in the Parent Company financial statements. For further information on income taxes, see Note 10 of the Notes to the Consolidated Financial Statements. (D) Dividend Restrictions See Note 13 of the Notes to the Consolidated Financial Statements for information regarding dividend restrictions. (E) Supplemental Disclosures of Cash Flow Information (In millions) 2019 2018 2017 Interest paid $ 189 $ 179 $ 195 Noncash financing activities: Treasury stock issued for shareholder dividend reinvestment 30 8 29

SCHEDULE III SUPPLEMENTARY INSU

SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION	12 Months Ended
SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION	Dec. 31, 2019
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Abstract]
SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION	SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION Aflac Incorporated and Subsidiaries Years ended December 31, (In millions) Deferred Policy Future Policy Unearned Other 2019: Aflac Japan $ 6,584 $ 84,341 $ 4,135 $ 7,317 Aflac U.S. 3,544 11,184 111 0 All other 0 223 0 0 Intercompany eliminations 0 (754 ) (3 ) 0 Total $ 10,128 $ 94,994 $ 4,243 $ 7,317 2018: Aflac Japan $ 6,384 $ 80,672 $ 4,977 $ 7,145 Aflac U.S. 3,491 10,864 117 0 All other 0 183 0 1 Intercompany eliminations 0 (767 ) (4 ) 0 Total $ 9,875 $ 90,952 $ 5,090 $ 7,146 Segment amounts may not agree in total to the corresponding consolidated amounts due to rounding. Years Ended December 31, (In millions) Net Net Benefits and Amortization of Other Premiums 2019: Aflac Japan $ 12,772 $ 2,753 $ 8,877 $ 709 $ 2,465 $ 12,367 Aflac U.S. 5,808 720 2,871 573 1,834 5,813 All other 200 105 194 0 339 0 Total $ 18,780 $ 3,578 $ 11,942 $ 1,282 $ 4,638 $ 18,180 2018: Aflac Japan $ 12,762 $ 2,639 $ 8,913 $ 710 $ 2,374 $ 12,298 Aflac U.S. 5,708 727 2,887 534 1,736 5,707 All other 207 76 200 1 420 0 Total $ 18,677 $ 3,442 $ 12,000 $ 1,245 $ 4,530 $ 18,005 2017: Aflac Japan $ 12,752 $ 2,463 $ 9,087 $ 630 $ 2,257 $ 12,092 Aflac U.S. 5,563 721 2,885 502 1,658 5,565 All other 216 36 209 0 421 0 Total $ 18,531 $ 3,220 $ 12,181 $ 1,132 $ 4,336 $ 17,657 Segment amounts may not agree in total to the corresponding consolidated amounts due to rounding. See the accompanying Report of Independent Registered Public Accounting Firm.

SCHEDULE IV REINSURANCE

SCHEDULE IV REINSURANCE	12 Months Ended
SCHEDULE IV REINSURANCE	Dec. 31, 2019
Reinsurance Disclosures [Abstract]
SCHEDULE IV REINSURANCE	SCHEDULE IV REINSURANCE Aflac Incorporated and Subsidiaries Years Ended December 31, (In millions) Gross Ceded to Assumed Net Percentage 2019: Life insurance in force $ 146,585 $ 6,592 $ 0 $ 139,993 0 % Premiums: Health insurance $ 15,657 $ 527 $ 205 $ 15,335 1 % Life insurance 3,465 20 0 3,445 0 Total earned premiums $ 19,122 $ 547 $ 205 $ 18,780 1 % 2018: Life insurance in force $ 151,457 $ 4,702 $ 0 $ 146,755 0 % Premiums: Health insurance $ 15,330 $ 541 $ 214 $ 15,003 1 % Life insurance 3,688 14 0 3,674 0 Total earned premiums $ 19,018 $ 555 $ 214 $ 18,677 1 % 2017: Life insurance in force $ 152,502 $ 4,121 $ 0 $ 148,381 0 % Premiums: Health insurance $ 14,829 $ 554 $ 222 $ 14,497 1 % Life insurance 4,046 12 0 4,034 0 Total earned premiums $ 18,875 $ 566 $ 222 $ 18,531 1 % Premiums by type may not agree in total to the corresponding consolidated amounts due to rounding. See the accompanying Report of Independent Registered Public Accounting Firm.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business Aflac Incorporated (the Parent Company) and its subsidiaries (collectively, the Company) primarily sell supplemental health and life insurance in the United States (U.S.) and Japan. The Company's insurance business is marketed and administered through American Family Life Assurance Company of Columbus (Aflac) in the U.S. and, effective April 1, 2018, through Aflac Life Insurance Japan Ltd. (ALIJ) in Japan. Prior to April 1, 2018, the Company's insurance business was marketed in Japan as a branch of Aflac. The Company’s operations consist of two reportable business segments: Aflac U.S., which includes Aflac, and Aflac Japan, which includes ALIJ. American Family Life Assurance Company of New York (Aflac New York) is a wholly owned subsidiary of Aflac. Most of Aflac's policies are individually underwritten and marketed through independent agents. Additionally, Aflac U.S. markets and administers group products through Continental American Insurance Company (CAIC), branded as Aflac Group Insurance. The Company's insurance operations in the U.S. and Japan service the two markets for the Company's insurance business. Aflac Japan's revenues, including realized gains and losses on its investment portfolio, accounted for 69% of the Company's total revenues in 2019 , compared with 70% in both 2018 and 2017 . The percentage of the Company's total assets attributable to Aflac Japan was 83% at December 31, 2019 , compared with 84% at December 31, 2018 . In November 2019, the Company acquired Argus Holdings, LLC and its subsidiary Argus Dental & Vision, Inc. (Argus), a benefits management organization and national network dental and vision company, which provides a platform for Aflac Dental and Vision. The Company paid $75 million at closing and made an additional commitment of up to $21 million in contingent consideration payable over three years based on the achievement by Argus of certain performance targets. Argus is an addition to the Aflac U.S. segment. Basis of Presentation The Company prepares its financial statements in accordance with U.S. generally accepted accounting principles (U.S. GAAP). These principles are established primarily by the Financial Accounting Standards Board (FASB). In these Notes to the Consolidated Financial Statements, references to U.S. GAAP issued by the FASB are derived from the FASB Accounting Standards Codification TM (ASC). The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates based on currently available information when recording transactions resulting from business operations. The most significant items on the Company's balance sheet that involve a greater degree of accounting estimates and actuarial determinations subject to changes in the future are the valuation of investments and derivatives, deferred policy acquisition costs (DAC), liabilities for future policy benefits and unpaid policy claims, and income taxes. These accounting estimates and actuarial determinations are sensitive to market conditions, investment yields, mortality, morbidity, commission and other acquisition expenses, and terminations by policyholders. As additional information becomes available, or actual amounts are determinable, the recorded estimates will be revised and reflected in operating results. Although some variability is inherent in these estimates, the Company believes the amounts provided are adequate. The consolidated financial statements include the accounts of the Parent Company, its subsidiaries, and those entities required to be consolidated under applicable accounting standards. All material intercompany accounts and transactions have been eliminated.
Translation of Foreign Currencies	Foreign Currency Translation: The functional currency of Aflac Japan is the Japanese yen. The Company translates its yen-denominated financial statement accounts into U.S. dollars as follows. Assets and liabilities are translated at end-of-period exchange rates. Realized gains and losses on security transactions are translated at the exchange rate on the trade date of each transaction. Other revenues, expenses, and cash flows are translated using average exchange rates for the period. The resulting currency translation adjustments are reported in accumulated other comprehensive income. The Company includes in earnings the realized currency exchange gains and losses resulting from foreign currency transactions. The Parent Company has designated a majority of its yen-denominated liabilities (notes payable and yen-denominated loans) as non-derivative hedges and from time-to-time may designate certain foreign currency forwards and options as derivative hedges of the foreign currency exposure of the Company's net investment in Aflac Japan. Outstanding principal and related accrued interest on these Parent Company liabilities and the fair value of these derivatives are translated into U.S. dollars at end-of-period exchange rates. Currency translation adjustments and changes in the fair value of these derivatives are recorded as unrealized foreign currency translation gains (losses) in other comprehensive income and are included in accumulated other comprehensive income.
Insurance Revenue and Expense Recognition	Insurance Revenue and Expense Recognition: Substantially all of the supplemental health and life insurance policies the Company issues are classified as long-duration contracts. The contract provisions generally cannot be changed or canceled during the contract period; however, the Company may adjust premiums for supplemental health policies issued in the U.S. within prescribed guidelines and with the approval of state insurance regulatory authorities. Insurance premiums for most of the Company's health and life policies, including cancer, accident, hospital, critical illness, dental, vision, term life, whole life, long-term care and disability, are recognized as revenue over the premium-paying periods of the contracts when due from policyholders. When revenues are reported, the related amounts of benefits and expenses are charged against such revenues, so that profits are recognized in proportion to premium revenues during the period the policies are expected to remain in force. This association is accomplished by means of annual additions to the liability for future policy benefits and the deferral and subsequent amortization of policy acquisition costs. Premiums from the Company's products with limited-pay features, including term life, whole life, WAYS, and child endowment, are collected over a significantly shorter period than the period over which benefits are provided. Premiums for these products are recognized as revenue over the premium-paying periods of the contracts when due from policyholders. Any gross premium in excess of the net premium is deferred and recorded in earnings, such that profits are recognized in a constant relationship with insurance in force. Benefits are recorded as an expense when they are incurred. A liability for future policy benefits is recorded when premiums are recognized using the net premium method. At the policyholder's option, customers can also pay discounted advanced premiums for certain of the Company's products. Advanced premiums are deferred and recognized when due from policyholders over the regularly scheduled premium payment period. The calculation of DAC and the liability for future policy benefits requires the use of estimates based on sound actuarial valuation techniques. For new policy issues, the Company reviews its actuarial assumptions and deferrable acquisition costs each year and revises them when necessary to more closely reflect recent experience and studies of actual acquisition costs. For policies in force, the Company evaluates DAC by major product groupings to determine that they are recoverable from future revenues, and any amounts determined not to be recoverable are charged against net earnings. The Company has not had any material charges to earnings for DAC that was determined not to be recoverable in any of the years presented in this Form 10-K.
Advertising Cost, Policy, Expensed Advertising Cost	Advertising expense is reported as incurred in insurance expenses in the consolidated statements of earnings.
Cash and Cash Equivalents	Cash and Cash Equivalents: Cash and cash equivalents include cash on hand, money market instruments, and other debt instruments with a maturity of 90 days or less when purchased.
Investments	Investments: The Company's debt securities consist of fixed maturity securities, which are classified as either held to maturity or available for sale. Securities classified as held to maturity are securities that the Company has the ability and intent to hold to maturity or redemption and are carried at amortized cost. All other fixed maturity debt securities are classified as available for sale and are carried at fair value. If the fair value is higher than the amortized cost for debt securities, the excess is an unrealized gain, and if lower than cost, the difference is an unrealized loss. The net unrealized gains and losses on securities available for sale, less related deferred income taxes, are recorded through other comprehensive income and included in accumulated other comprehensive income. Amortized cost of debt securities is based on the Company's purchase price adjusted for accrual of discount, or amortization of premium, and recognition of impairment charges, if any. The amortized cost of debt securities the Company purchases at a discount or premium will equal the face or par value at maturity or the call date, if applicable. Interest is reported as income when earned and is adjusted for amortization of any premium or discount. The Company has investments in marketable equity securities which are carried at fair value. Changes in the fair value of equity securities are recorded in earnings as a component of realized investment gains and losses. The Company has investments in variable interest entities (VIEs). Criteria for evaluating VIEs for consolidation focuses on identifying which enterprise has the power to direct the activities of a variable interest entity that most significantly impact the entity's economic performance and (1) the obligation to absorb losses of the entity or (2) the right to receive benefits from the entity. The Company is the primary beneficiary of certain VIEs, and therefore consolidates these entities in its financial statements. While the consolidated VIEs generally operate within a defined set of contractual terms, there are certain powers that are retained by the Company that are considered significant in the conclusion that the Company is the primary beneficiary. These powers vary by structure but generally include the initial selection of the underlying collateral; the ability to obtain the underlying collateral in the event of default; and, the ability to appoint or dismiss key parties in the structure. In particular, the Company's powers surrounding the underlying collateral were considered to be the most significant powers because those most significantly impact the economics of the VIE. The Company has no obligation to provide any continuing financial support to any of the entities in which it is the primary beneficiary. The Company's maximum loss is limited to its original investment. Neither the Company nor any of its creditors have the ability to obtain the underlying collateral, nor does the Company have control over the instruments held in the VIEs, unless there is an event of default. For those entities where the Company is the primary beneficiary, the consolidated entity's assets are segregated on the balance sheet by the caption "consolidated variable interest entities," and consist of fixed maturity securities, equity securities, loan receivables, limited partnerships and derivative instruments. For the mortgage- and asset-backed securities held in the Company's fixed maturity portfolio, the Company recognizes income using a constant effective yield, which is based on anticipated prepayments and the estimated economic life of the securities. When estimates of prepayments change, the effective yield is recalculated to reflect actual payments to date and anticipated future payments. The net investment in mortgage- and asset-backed securities is adjusted to the amount that would have existed had the new effective yield been applied at the time of acquisition. This adjustment is reflected in net investment income. The Company uses the specific identification method to determine the gain or loss from securities transactions and report the realized gain or loss in the consolidated statements of earnings. Securities transactions are accounted for based on values as of the trade date of the transaction. An investment in a fixed maturity security is impaired if the fair value falls below amortized cost. The Company regularly reviews its fixed maturity security investments portfolio for declines in fair value. The Company's fixed maturity security investments are evaluated for other-than-temporary impairment using its debt impairment model. The Company's debt impairment model focuses on the ultimate collection of the cash flows from its investments and whether the Company has the intent to sell or if it is more likely than not the Company would be required to sell the security prior to recovery of its amortized cost. The determination of the amount of impairments under this model is based upon the Company's periodic evaluation and assessment of known and inherent risks associated with the respective securities. Such evaluations and assessments are revised as conditions change and new information becomes available. When determining the Company's intention to sell a security prior to recovery of its fair value to amortized cost, the Company evaluates facts and circumstances such as, but not limited to, future cash flow needs, decisions to reposition its security portfolio, and risk profile of individual investment holdings. The Company performs ongoing analyses of its liquidity needs, which includes cash flow testing of its policy liabilities, debt maturities, projected dividend payments, and other cash flow and liquidity needs. The determination of whether an impairment in value of the Company's fixed maturity securities is other than temporary is based largely on the Company's evaluation of the issuer ' s creditworthiness. The Company must apply considerable judgment in determining the likelihood of its fixed maturity securities recovering in value. Factors that may influence this include the overall level of interest rates, credit spreads, the credit quality of the underlying issuer, and other factors. This process requires consideration of risks which can be controlled to a certain extent, such as credit risk, and risks which cannot be controlled, such as interest rate risk and foreign currency risk. If, after monitoring and analyses, management believes that fair value will not recover to amortized cost, the Company recognizes an other-than-temporary impairment of the security. Once a security is considered to be other-than-temporarily impaired, the impairment loss is separated into two components: the portion of the impairment related to credit and the portion of the impairment related to factors other than credit. The Company recognizes a charge to earnings for the credit-related portion of other-than-temporary impairments. Impairments related to factors other than credit are charged to earnings in the event the Company intends to sell the security prior to the recovery of its amortized cost or if it is more likely than not that the Company would be required to dispose of the security prior to recovery of its amortized cost; otherwise, non-credit-related other-than-temporary impairments are charged to other comprehensive income. The Company lends fixed maturity and public equity securities to financial institutions in short-term security-lending transactions. These securities continue to be carried as investment assets on the Company's balance sheet during the terms of the loans and are not reported as sales. The Company receives cash or other securities as collateral for such loans. For loans involving unrestricted cash or securities as collateral, the collateral is reported as an asset with a corresponding liability for the return of the collateral. For loans where the Company receives as collateral securities that the Company is not permitted to sell or repledge, the collateral is not reported as an asset. Commercial mortgage and other loans include transitional real estate loans (TREs), commercial mortgage loans (CMLs) and middle market loans (MMLs). The Company's investments in TREs, CMLs, and MMLs are accounted for as loan receivables and are recorded at amortized cost on the acquisition date. The Company has the intent and ability to hold these loan receivables for the foreseeable future or until they mature and therefore, they are considered held for investment and are carried at amortized cost in the commercial mortgage and other loans line in its consolidated balance sheets. The amortized cost of the loan receivables reflects allowances for expected incurred losses estimated based on past events and current economic conditions as of each reporting date. Other investments include policy loans, limited partnerships, and short-term investments with maturities at the time of purchase of one year or less, but greater than 90 days. Limited partnerships are accounted for using the equity method of accounting. Under the equity method of accounting, the Company reports its portion of partnership earnings as a component of net investment income in its consolidated statements of earnings. The underlying investments held by the Company’s limited partnerships primarily consist of private equity and real estate. Short-term investments are stated at amortized cost, which approximates fair value.
Derivatives and Hedging	Derivatives and Hedging: Freestanding derivative instruments are reported in the consolidated balance sheet at fair value and are reported in other assets and other liabilities, with changes in value reported in earnings and/or other comprehensive income. These freestanding derivatives are foreign currency forwards, foreign currency options, foreign currency swaps, interest rate swaps, interest rate swaptions, and, in prior year periods, credit default swaps (CDSs). The Company does not use derivatives for trading purposes, nor does the Company engage in leveraged derivative transactions. From time to time, the Company purchases certain investments that contain an embedded derivative. The Company assesses whether this embedded derivative is clearly and closely related to the asset that serves as its host contract. If the Company deems that the embedded derivative's terms are not clearly and closely related to the host contract, and a separate instrument with the same terms would qualify as a derivative instrument, the derivative is separated from that contract, held at fair value, and reported with the host instrument in the consolidated balance sheet, with changes in fair value reported in earnings. If the Company has elected the fair value option, the embedded derivative is not bifurcated, and the entire investment is held at fair value with changes in fair value reported in earnings. See Note 5 for a discussion on how the Company determines the fair value of its derivatives. Accruals on derivatives are typically recorded in other assets or within other liabilities in the consolidated balance sheets. To qualify for hedge accounting treatment, a derivative must be highly effective in mitigating the designated risk attributable to the hedged item. At the inception of hedging relationships the Company formally documents all relationships between hedging instruments and hedged items, as well as its risk-management objectives and strategies for undertaking the respective hedging relationship, and the methodology that will be used to assess the effectiveness of the hedge relationship at and subsequent to hedge inception. The Company documents the designation of each hedge as either (i) a hedge of the variability of cash flows to be received or paid related to a recognized asset or liability or the hedge of a forecasted transaction ("cash flow hedge"); (ii) a hedge of the estimated fair value of a recognized asset or liability ("fair value hedge"); or (iii) a hedge of a net investment in a foreign operation. The documentation process includes linking derivatives and non-derivative financial instruments that are designated as hedges to specific assets or groups of assets or liabilities in the statement of financial position or to specific forecasted transactions and defining the effectiveness testing methods to be used. At the hedge inception and on an ongoing quarterly basis, the Company also formally assesses whether the derivatives and non-derivative financial instruments used in hedging activities have been, and are expected to continue to be, highly effective in offsetting their designated risk. Hedge effectiveness is assessed using qualitative and quantitative methods. The assessment of hedge effectiveness determines the accounting treatment of changes in fair value. For assessing hedge effectiveness, qualitative methods may include the comparison of critical terms of the derivative to the hedged item, and quantitative methods may include regression, dollar offset, or other statistical analysis of changes in fair value or cash flows associated with the hedge relationship. For derivative instruments that are designated and qualify as cash flow hedges, the gain or loss on the derivative is reported as a component of other comprehensive income (loss) and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. In cash flow hedges, all components of each derivative's gain or loss are included in the assessment of hedge effectiveness. For derivative instruments that are designated and qualify as fair value hedges, the gain or loss on the hedged item and the portion of the hedging instrument included in the assessment of effectiveness are recorded in the line item of the consolidated statements of earnings in which gain or loss on the hedged item is recorded. When assessing the effectiveness of the Company's fair value hedges, the Company excludes the changes in fair value related to the difference between the spot and the forward rate on its foreign currency forwards and the time value of money of foreign exchange options and interest rate swaptions. For interest rate swaptions designated under fair value hedges of interest rate risk, the change in the time value of money is recognized in other comprehensive income (loss) and amortized into earnings (net investment income) over its legal term. As discussed in Note 4, from time to time the Company designates net investment hedges of its net investment in Aflac Japan. The Company makes its net investment hedge designation at the beginning of each quarter. For derivative hedging instruments designated as net investment hedges, Aflac follows the spot-rate method. According to that method, the change in fair value of the hedging instrument due to fluctuations in the spot exchange rate is recorded in the unrealized foreign currency component of other comprehensive income and reclassified to earnings only when the hedged net investment is sold, or when a liquidation of the respective net investment in the foreign entity is substantially completed. If and when a sale or liquidation occurs, the changes in fair value of the derivative deferred in the unrealized foreign currency component of other comprehensive income will be released in the same income statement line item where the gain (loss) on the hedged net investment would be recorded upon sale. All other changes in fair value of the hedging instrument are considered the “excluded component” and are accounted for in realized investment gains (losses). Should these designated net investment hedge positions exceed the Company's net investment in Aflac Japan, the foreign exchange effect on the portion that exceeds its investment in Aflac Japan would be recognized in current earnings within realized investment gains (losses). The Company discontinues hedge accounting prospectively when (1) it is determined that the derivative is no longer highly effective in offsetting changes in the estimated cash flows or fair value of a hedged item; (2) the derivative is de-designated as a hedging instrument; or (3) the derivative expires or is sold, terminated or exercised. When hedge accounting is discontinued on a cash flow hedge or fair value hedge, the derivative is carried in the consolidated balance sheets at its estimated fair value, with changes in estimated fair value recognized in current period earnings. For discontinued cash flow hedges, including those where the derivative is sold, terminated or exercised, amounts previously deferred in other comprehensive income (loss) are reclassified into earnings when earnings are impacted by the cash flow of the hedged item. If a derivative is not designated as an accounting hedge or its use in managing risk does not qualify for hedge accounting, changes in the estimated fair value of the derivative are generally reported within other gains (losses), which is a component of realized investment gains (losses). The fluctuations in estimated fair value of derivatives that have not been designated for hedge accounting can result in volatility in net earnings. The Company receives and pledges cash or other securities as collateral on open derivative positions. Cash received as collateral is reported as an asset with a corresponding liability for the return of the collateral. Cash pledged as collateral is recorded as a reduction to cash, and a corresponding receivable is recognized for the return of the cash collateral. The Company generally can repledge or resell collateral obtained from counterparties, although the Company does not typically exercise such rights. Securities received as collateral are not recognized unless the Company was to exercise its right to sell that collateral or exercise remedies on that collateral upon a counterparty default. Securities that the Company has pledged as collateral continue to be carried as investment assets on its balance sheet.
Deferred Policy Acquisition Costs	Deferred Policy Acquisition Costs: Certain direct and incremental costs of acquiring new business are deferred and amortized with interest over the premium payment periods in proportion to the ratio of annual premium income to total anticipated premium income. Anticipated premium income is estimated by using the same mortality, persistency and interest assumptions used in computing liabilities for future policy benefits. In this manner, the related acquisition expenses are matched with revenues. Deferred costs include the excess of current-year commissions over ultimate renewal-year commissions and certain incremental direct policy issue, underwriting and sales expenses. All of these incremental costs are directly related to successful policy acquisition. For some products, policyholders can elect to modify product benefits, features, rights or coverages by exchanging a contract for a new contract or by amendment, endorsement, or rider to a contract, or by the election of a feature or coverage within a contract. These transactions are known as internal replacements. The Company performs a two-stage analysis of the internal replacements to determine if the modification is substantive to the base policy. The stages of evaluation are as follows: 1) determine if the modification is integrated with the base policy, and 2) if it is integrated, determine if the resulting contract is substantially changed. For internal replacement transactions where the resulting contract is substantially unchanged, the policy is accounted for as a continuation of the replaced contract. Unamortized deferred acquisition costs from the original policy continue to be amortized over the expected life of the new policy, and the costs of replacing the policy are accounted for as policy maintenance costs and expensed as incurred. Examples include conversions of same age bands, certain family coverage changes, pricing era changes (decrease), and ordinary life becomes reduced paid-up and certain reinstatements. An internal replacement transaction that results in a policy that is substantially changed is accounted for as an extinguishment of the original policy and the issuance of a new policy. Unamortized deferred acquisition costs on the original policy are immediately expensed, and the costs of acquiring the new policy are capitalized and amortized in accordance with the Company's accounting policies for deferred acquisition costs. Further, the policy reserves are evaluated based on the new policy features, and any change (up or down) necessary is recognized at the date of contract change/modification. Examples include conversions to higher age bands, certain family coverage changes, pricing era changes (increase), lapse & re-issue, certain reinstatements and certain other contract conversions. Riders can be considered internal replacements that are either integrated or non-integrated resulting in either substantially changed or substantially unchanged treatment. Riders are evaluated based on the specific facts and circumstances of the rider and are considered an expansion of the existing benefits with additional premium required. Non-integrated riders to existing contracts do not change the Company's profit expectations for the related products and are treated as a new policy establishment for incremental coverage. The Company measures the recoverability of DAC and the adequacy of its policy reserves annually by performing gross premium valuations on its business. (See the following discussion for further information regarding policy reserves.)
Policy Liabilities - Future Policy Benefits	Policy Liabilities: Future policy benefits represent claims that are expected to occur in the future and are computed following a net level premium method using estimated future investment yields, persistency and recognized morbidity and mortality tables modified to reflect the Company's experience, including a provision for adverse deviation. These assumptions are generally established and considered locked at policy inception. These assumptions may only be unlocked in certain circumstances based on the results of periodic DAC recoverability and premium deficiency testing.
Policy Liabilities - Unpaid Policy Claims	Unpaid policy claims are estimates computed primarily on an undiscounted basis using statistical analyses of historical claims experience adjusted for current trends and changed conditions. The ultimate liability may vary significantly from such estimates. The Company regularly adjusts these estimates as new claims experience emerges and reflects the changes in operating results in the year such adjustments are made.
Unearned Premiums	Unearned premiums consist primarily of discounted advance premiums on deposit from policyholders in conjunction with their purchase of certain Aflac Japan limited-pay insurance products. These advanced premiums are deferred upon collection and recognized as premium revenue over the contractual premium payment period.
Other Policy Liabilities	Other policyholders’ funds liability consists primarily of the fixed annuity line of business in Aflac Japan which has fixed benefits and premiums.
Internal Replacements of Insurance Contracts	For internal replacements that are determined to not be substantially unchanged, policy liabilities related to the original policy that was replaced are immediately released, and policy liabilities are established for the new insurance contract; however, for internal replacements that are considered substantially unchanged, no changes to the reserves are recognized.
Reinsurance Accounting Policy	Reinsurance: The Company enters into reinsurance agreements with other companies in the normal course of business. For each reinsurance agreement, the Company determines if the agreement provides indemnification against loss or liability relating to insurance risk in accordance with applicable accounting standards. Reinsurance premiums and benefits paid or provided are accounted for on bases consistent with those used in accounting for the original policies issued and the terms of the reinsurance contracts. Premiums, benefits and DAC are reported net of insurance ceded.
Income Taxes	Income Taxes: Income tax provisions are generally based on pretax earnings reported for financial statement purposes, which differ from those amounts used in preparing the Company's income tax returns. Deferred income taxes are recognized for temporary differences between the financial reporting basis and income tax basis of assets and liabilities, based on enacted tax laws and statutory tax rates applicable to the periods in which the Company expects the temporary differences to reverse. The Company records deferred tax assets for tax positions taken based on its assessment of whether the tax position is more likely than not to be sustained upon examination by taxing authorities. A valuation allowance is established for deferred tax assets when it is more likely than not that an amount will not be realized.
Policyholder Protection Corporation and State Guaranty Association Assessments	Policyholder Protection Corporation and State Guaranty Association Assessments: In Japan, the government has required the insurance industry to contribute to a policyholder protection corporation. The Company recognizes a charge for its estimated share of the industry's obligation once it is determinable. The Company reviews the estimated liability for policyholder protection corporation contributions on an annual basis and reports any adjustments in Aflac Japan's expenses. In the U.S., each state has a guaranty association that supports insolvent insurers operating in those states. The Company's policy is to accrue assessments when the entity for which the insolvency relates has met its state of domicile's statutory definition of insolvency, the amount of the loss is reasonably estimable and the related premium upon which the assessment is based is written. See Note 15 of the Notes to the Consolidated Financial Statements for further discussion of the guaranty fund assessments charged to the Company.
Treasury Stock	Treasury Stock: Treasury stock is reflected as a reduction of shareholders' equity at cost. The Company uses the weighted-average purchase cost to determine the cost of treasury stock that is reissued. The Company includes any gains and losses in additional paid-in capital when treasury stock is reissued.
Share-Based Compensation	Share-Based Compensation: The Company measures compensation cost related to its share-based payment transactions at fair value on the grant date, and the Company recognizes those costs in the financial statements over the vesting period during which the employee provides service in exchange for the award. The Company has formalized its entity-wide accounting policy election to estimate the number of awards that are expected to vest and the corresponding forfeitures.
Earnings Per Share	Earnings Per Share: The Company computes basic earnings per share (EPS) by dividing net earnings by the weighted-average number of unrestricted shares outstanding for the period. Diluted EPS is computed by dividing net earnings by the weighted-average number of shares outstanding for the period plus the shares representing the dilutive effect of share-based awards.
Reclassifications	Reclassifications: Certain reclassifications have been made to prior-year amounts to conform to current-year reporting classifications. These reclassifications had no impact on net earnings or total shareholders' equity.
Recently Adopted Accounting Pronouncements	New Accounting Pronouncements Recently Adopted Accounting Pronouncements Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters Accounting Standard Update (ASU) 2018-16 Derivatives and Hedging Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes In October 2018, the FASB issued amendments to permit use of the Overnight Index Swap (OIS) rate based on the Secured Overnight Financing Rate (SOFR) as a U.S. benchmark interest rate for hedge accounting purposes under Topic 815 in addition to the Treasury obligations of the U.S. government (UST), the London Interbank Offered Rate (LIBOR) swap rate, the OIS rate based on the Fed Funds Effective Rate, and the Securities Industry and Financial Markets Association (SIFMA) Municipal Swap Rate. Early adopted as of October 1, 2018 The adoption of this guidance did not have a significant impact on the Company’s financial position, results of operations or disclosures. ASU 2018-15 Intangibles - Goodwill and Other - Internal-Use Software, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In August 2018, the FASB issued amendments to align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. Early adopted as of January 1, 2019 The adoption of this guidance did not have a significant impact on the Company’s financial position, results of operations or disclosures. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2018-14 Compensation - Retirement Benefits - Defined Benefit Plans - General, Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans In August 2018, the FASB issued amendments to modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. Accordingly, six disclosures requirements were removed, two added and two clarified. Early adopted as of December 31, 2019 The adoption of this guidance did not have a significant impact on the Company’s financial position, results of operations or disclosures. ASU 2018-03 Technical Corrections and Improvements to Financial Instruments - Overall Recognition and Measurement of Financial Assets and Financial Liabilities In February 2018, the FASB issued amendments to clarify certain aspects of the guidance issued in the original Financial Instruments - Overall - Recognition and Measurement pronouncement summarized below. Specifically, for entities who have chosen the measurement alternative approach for equity securities without readily determinable fair values, the amendments clarify that entities may change from a measurement alternative approach to a fair value method through an irrevocable election that would apply to a specific equity security and all identical or similar investments of the same issuer; entities should use an observable price at the date of the transaction rather than reporting date for the measurement alternative calculation; and insurance companies should use a prospective transition method when applying the measurement alternative. Early adopted as of January 1, 2018 The adoption of this guidance did not have a significant impact on the Company’s financial position, results of operations, or disclosures. ASU 2018-02 Income Statement - Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the FASB issued amendments which allow a reclassification from accumulated other comprehensive income (AOCI) to retained earnings of the effects of the change in the U.S. federal income tax rate resulting from the Tax Cuts and Jobs Act (Tax Act) on the gross deferred tax amounts and the corresponding valuation allowances related to items remaining in AOCI. The amendments eliminate the stranded tax effects resulting from the Tax Act and also require certain disclosures about the reclassified tax effects. Early adopted as of January 1, 2018 The amounts reclassified from AOCI to retained earnings include the income tax effects of the change in the federal corporate tax rate enacted by the Tax Act. The Company’s policy is to follow the portfolio approach for releasing income tax effects from AOCI. The adoption of this guidance resulted in an increase to beginning 2018 AOCI of $374 million with a corresponding decrease to beginning 2018 retained earnings as of January 1, 2018. ASU 2017-12 Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities In August 2017, the FASB issued guidance which improves and simplifies the accounting rules around hedge accounting and creates more transparency around how economic results are presented in financial statements. Issues addressed in this new guidance include: 1) risk component hedging, 2) accounting for the hedged item in fair value hedges of interest rate risk, 3) recognition and presentation of the effects of hedging instruments, and 4) amounts excluded from the assessment of hedge effectiveness. Early adopted as of October 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2017-09 Compensation - Stock Compensation: Scope of Modification Accounting In May 2017, the FASB issued amendments to provide guidance clarifying when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. An entity should apply modification accounting if the fair value, vesting conditions or classification of the award (as an equity instrument or liability instrument) changes as a result of the change in terms or conditions of the award. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-08 Receivables - Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities In March 2017, the FASB issued amendments to shorten the amortization period for certain callable debt securities held at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount. Early adopted as of July 1, 2018 The adoption of this guidance did not have a significant impact on the Company’s financial position, results of operations, or disclosures. ASU 2017-07 Compensation - Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost In March 2017, the FASB issued amendments requiring that an employer report the service cost component of net periodic pension cost and net periodic postretirement benefit cost in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net periodic pension cost and net periodic postretirement benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. If a separate line item or items are used to present the other components of net benefit cost, that line item or items must be appropriately described. If a separate line item or items are not used, the line item or items used in the income statement to present the other components of net benefit cost must be disclosed. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-05 Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets: Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets In February 2017, the FASB issued amendments that clarify the scope and accounting guidance for the derecognition of a nonfinancial asset or a financial asset that meets the definition of an "in substance nonfinancial asset." The amendments define an "in substance nonfinancial asset" and provide additional accounting guidance for partial sales of nonfinancial assets. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-01 Business Combinations: Clarifying the Definition of a Business In January 2017, the FASB issued amendments clarifying when a set of assets and activities is a business. The amendments provide a screen to exclude transactions where substantially all the fair value of the transferred set is concentrated in a single asset, or group of similar assets, from being evaluated as a business. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2016-18 Statement of Cash Flows: Restricted Cash In November 2016, the FASB issued amendments requiring that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, statements of cash flows, or disclosures. ASU 2016-17 Consolidation - Interests Held through Related Parties That Are under Common Control In October 2016, the FASB issued amendments which clarify the consolidation guidance on how a reporting entity that is the single decision maker of a variable interest entity (VIE) should treat indirect interests in the entity held through related parties that are under common control with the reporting entity when determining whether it is the primary beneficiary of that VIE. January 1, 2017 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2016-16 Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued amendments that require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2016-15 Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued amendments that provide guidance on eight specific statement of cash flow classification issues, including distributions received from equity method investees. January 1, 2018 The Company elected nature of distribution for distributions received from equity method investees. The adoption of this guidance did not have a significant impact on the Company's financial position, statement of cash flows, results of operations, or disclosures. ASU 2016-09 Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting In March 2016, the FASB issued amendments which simplify several aspects for share-based payment award transactions, including the income tax consequences, classification of awards as either liability or equity, classification of taxes paid on the statement of cash flows and treatment of forfeitures. January 1, 2017 As a result of applying this requirement, the Company believes that recognition of excess tax benefits will increase volatility in its statement of operations and the Company made an entity-wide accounting policy election to estimate the number of awards that are expected to vest (consistent with the Company's prior policy), but the adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, statements of cash flows, or disclosures. ASU 2016-07 Investments - Equity Method and Joint Ventures - Simplifying the Transition to the Equity Method of Accounting In March 2016, the FASB issued amendments which eliminate the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations, and retained earnings retroactively on a step-by-step basis as if the equity method had been in effect during all previous periods that the investment had been held. Per the amendments, upon qualifying for the equity method of accounting, no retroactive adjustment of the investment is required. January 1, 2017 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2016-06 Derivatives and Hedging - Contingent Put and Call Options in Debt Instruments In March 2016, the FASB issued amendments which clarify what steps are required when assessing whether the economic characteristics and risks of call (put) options are clearly and closely related to the economic characteristics and risks of their debt hosts, which is one of the criteria for bifurcating an embedded derivative. Consequently, when a call (put) option is contingently exercisable, an entity does not have to assess whether the event that triggers the ability to exercise a call (put) option is related to interest rates or credit risks. January 1, 2017 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2016-05 Derivatives and Hedging - Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships In March 2016, the FASB issued amendments which clarify that a change in the counterparty to a derivative instrument that has been designated as the hedging instrument does not, in and of itself, require dedesignation of that hedging relationship provided that all other hedge accounting criteria remain intact. January 1, 2017 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2016-02 Leases ASU 2018-01 , Leases: Land Easement Practical Expedient for Transition to Topic 842, ASU 2018-10 , Codification Improvements to Topic 842, Leases, ASU 2018-11 , Leases, Targeted Improvements, and ASU 2018-20 , Leases: Narrow-Scope Improvements for Lessors In February 2016, the FASB issued updated guidance for accounting for leases (“Leases Update”). Per the Leases Update, lessees are required to recognize all leases on the balance sheet with the exception of short-term leases. A lease liability will be recorded for the obligation of a lessee to make lease payments arising from a lease. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. The Leases Update provided a number of optional practical expedients. The Company elected the "package of practical expedients," which permits the Company not to reassess under the new standard its prior conclusions about lease identification, lease classification and initial direct costs. Under the Leases Update, lessor accounting is largely unchanged. January 1, 2019 The Company has operating and finance leases for office space and equipment. The Company elected the short-term lease exemption for all classes of leases which allows the Company to not recognize right-of-use assets and lease liabilities on the consolidated balance sheet and allows the Company to recognize the lease expense for short-term leases on a straight-line basis over the lease term. The Company elected the practical expedient to not separate lease and non-lease components and applied it to all classes of leases where the non-lease components are not significant. Some of the Company's leases include options to extend or terminate the lease and the lease terms may include such options when it is reasonably certain that the Company will exercise that option. Certain leases also include options to purchase the leased property. The leases within scope of the leases update increased the Company's right-of-use assets and lease liabilities recorded in its consolidated balance sheet by $134 million. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2016-01 Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued guidance to address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. The main provisions of this guidance require certain equity investments to be measured at fair value with changes in fair value recognized in net earnings; separate presentation in other comprehensive income for changes in fair value of financial liabilities measured under the fair value option that are due to instrument-specific credit risk; and changes in disclosures associated with the fair value of financial instruments. The guidance also clarifies that entities should evaluate the need for a valuation allowance on a deferred tax asset (DTA) related to available-for-sale (AFS) securities in combination with the entity's other DTAs. January 1, 2018 The Company recorded a cumulative effect adjustment with an increase to beginning 2018 retained earnings and a decrease to beginning 2018 AOCI of $148 million, net of taxes.
Description of Accounting Pronouncements Pending Adoption	Accounting Pronouncements Pending Adoption Standard Description Effect on Financial Statements or Other Significant Matters ASU 2020-01 Clarifying the interactions between Topic 321, Topic 323, and Topic 815 In January 2020, the FASB issued amendments clarifying that an entity should consider observable transactions that require it to either apply or discontinue the equity method of accounting for the purposes of applying the measurement alternative in accordance with Topic 321 immediately before applying or upon discontinuing the equity method. In addition, the amendments clarify that for the purpose of applying certain derivative guidance in Topic 815, an entity should not consider whether, upon the settlement of the forward contract or exercise of the purchased option, individually or with existing investments, the underlying securities would be accounted for under the equity method in Topic 323 or the fair value option in accordance with the financial instruments guidance in Topic 825. An entity also would evaluate the remaining characteristics in Topic 815 to determine the accounting for those forward contracts and purchased options. The amendments are effective for public business entities for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. Early adoption is permitted. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Effect on Financial Statements or Other Significant Matters ASU 2019-04 Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments In April 2019, the FASB issued Codification improvements to clarify and correct certain areas of guidance amended as part of ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities; ASU 2016-13 , Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments; and ASU 2017-12 , Derivative and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The Company did not reclassify any assets from held-to-maturity to available-for-sale as part of its implementation of ASU 2017-12, and is therefore eligible to reclassify qualifying securities as a result of these clarifications. Effective on January 1, 2020, the Company anticipates the reclassification of approximately $6.9 billion (at amortized cost) of pre-payable fixed-maturity securities from the held-to-maturity to the available-for-sale category. This reclassification is expected to result in recording in accumulated other comprehensive income a net unrealized gain of approximately $800 million on an after-tax basis, based on the securities’ fair values on the reclassification date. The reclassification will impact the adoption of ASU 2016-13 which will be effective January 1, 2020 (see ASU 2016-13 below for additional details). ASU 2018-17 Consolidation: Targeted Improvements to Related Party Guidance for Variable Interest Entities In October 2018, the FASB issued targeted improvements which provide that indirect interests held through related parties under common control should be considered on a proportional basis for determining whether fees paid to decision makers and service providers are variable interests. The amendments are effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. The adoption of this guidance is not expected to have a significant impact on the Company’s financial position, results of operations or disclosures. ASU 2018-13 Fair Value Measurement, Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued amendments to the disclosure requirements on fair value measurements. The amendments remove, modify, and add certain disclosures. The amendments are effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. Further, an entity is permitted to early adopt any removed or modified disclosures upon issuance of this update and delay adoption of the additional disclosures until their effective date. The adoption of this guidance is not expected to have a significant impact on the Company’s financial position, results of operations, or disclosures. Standard Description Effect on Financial Statements or Other Significant Matters ASU 2018-12 Financial Services - Insurance, Targeted Improvements to the Accounting for Long-Duration Contracts as clarified and amended by: ASU No. 2019-09, Financial Services Insurance (Topic 944)- Effective Date In August 2018, the FASB issued amendments that will significantly change how insurers account for long-duration contracts. The amendments will change existing recognition, measurement, presentation, and disclosure requirements. Issues addressed in the new guidance include: 1) a requirement to review and, if there is a change, update assumptions for the liability for future policy benefits at least annually, and to update the discount rate assumption quarterly, 2) accounting for market risk benefits at fair value, 3) simplified amortization for deferred acquisition costs, and 4) enhanced financial statement presentation and disclosures. In November 2019, the FASB issued an amendment extending the effective date for public business entities that meet the definition of an SEC filer, excluding entities eligible to be small reporting companies as defined by the SEC, by one year. The amendments are now effective for the Company for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2021. Early application of the amendments is permitted. The Company is thoroughly evaluating the impact of adoption and expects that the adoption will have a significant impact on the Company’s financial position, results of operations, and disclosures. The Company anticipates that the requirement to update assumptions for liability for future policy benefits will have a significant impact on its results of operations, systems, processes and controls while the requirement to update the discount rate will have a significant impact on its equity. The Company has no products with market risk benefits. The Company does not expect to early adopt the updated standard and has tentatively selected a modified retrospective transition method. ASU 2017-04 Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued amendments simplifying the subsequent measurement of goodwill. An entity, under this update, is no longer required to perform a hypothetical purchase price allocation to measure goodwill impairment. Instead, the entity should perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. The amendments are effective for public business entities that are SEC filers for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for any goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Effect on Financial Statements or Other Significant Matters ASU 2016-13 Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments ASU 2019-04 , Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, ASU 2019-05 , Financial Instruments - Credit Losses (Topic 326), Targeted Transition Relief ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments- Credit Losses In June 2016, the FASB issued amendments that require a financial asset (or a group of financial assets) measured at amortized cost to be presented net of an allowance for credit losses (Credit Losses ASU) in order to reflect the amount expected to be collected on the financial asset(s). The measurement of expected credit losses is amended by replacing the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information. Credit losses on available-for-sale debt securities will be measured in a manner similar to current U.S. GAAP; however, the amendments require that credit losses be presented as an allowance rather than as a write-down. Other amendments include changes to the balance sheet presentation and interest income recognition of purchased financial assets with a more-than-insignificant credit deterioration since origination (PCD financial assets). The Company has identified the following financial instruments in scope of the new guidance: certain fixed maturity securities, loans and loan receivables, reinsurance recoverable, as well as certain other receivable balances and off-balance sheet arrangements. The Company has concluded that of the held-to-maturity fixed maturity securities, Japanese government and agency securities and certain Japanese government-guaranteed mortgage backed securities meet the requirements for a zero-loss expectation and therefore will not be included in the current expected credit loss measurement process upon adoption of the new standard. The Company has substantially completed the review and validation of credit models, methodologies and inputs for all asset classes. The Company performed parallel runs during the second, third and fourth quarters and refined its estimation process with additional parallel testing throughout 2019. The Company has estimated the adoption-date net after-tax impact at a $56 million decrease to retained earnings. As noted above relative to ASU 2019-04, the Company is planning a one-time reclassification as of January 1, 2020 of approximately $6.9 billion (amortized cost as of December 31, 2019) of its eligible fixed-maturity securities from held-to-maturity to available-for-sale category. The aforementioned reclassification has been reflected in the expected impact estimate from adoption of ASU 2016-13. The Company plans to adopt this ASU on January 1, 2020.

BUSINESS SEGMENT AND FOREIGN _2

BUSINESS SEGMENT AND FOREIGN INFORMATION (Tables)	12 Months Ended
BUSINESS SEGMENT AND FOREIGN INFORMATION (Tables)	Dec. 31, 2019
Segment Reporting [Abstract]
Reconciliation of Revenue from Segments to Consolidated	Information regarding operations by reportable segment and Corporate and other for the years ended December 31 follows: (In millions) 2019 2018 2017 Revenues: Aflac Japan: Net earned premiums: Cancer $ 6,031 $ 5,849 $ 5,612 Medical and other health 3,582 3,516 3,379 Life insurance 3,159 3,397 3,761 Net investment income, less amortized hedge costs (1),(2) 2,496 2,403 2,235 Other income 45 41 41 Total Aflac Japan 15,313 15,206 15,028 Aflac U.S.: Net earned premiums: Accident/disability 2,665 2,611 2,537 Cancer 1,309 1,311 1,308 Other health 1,548 1,508 1,445 Life insurance 286 278 273 Net investment income 720 727 721 Other income 22 8 5 Total Aflac U.S. 6,550 6,443 6,289 Corporate and other (3) 393 339 272 Total adjusted revenues 22,256 21,988 21,589 Realized investment gains (losses) (1),(2),(3) 51 (230 ) 78 Total revenues $ 22,307 $ 21,758 $ 21,667 (1) Amortized hedge costs of $257 , $236 and $228 in 2019 , 2018 and 2017 , respectively, related to certain foreign currency exposure management strategies have been reclassified from realized investment gains (losses) and reported as a deduction from net investment income when analyzing operations. (2) Net interest cash flows from derivatives associated with certain investment strategies of $(17) in 2019 and an immaterial amount in 2018 have been reclassified from realized investment gains (losses) and included in adjusted earnings as a component of net investment income. (3) Amortized hedge income of $89 in 2019 and $36 in 2018 related to certain foreign currency exposure management strategies has been reclassified from realized investment gains (losses) and reported as an increase to net investment income when analyzing operations.
Reconciliation of Adjusted Profit (Loss) from Segments to Consolidated	(In millions) 2019 2018 2017 Pretax earnings: Aflac Japan (1),(2) $ 3,261 $ 3,208 $ 3,054 Aflac U.S. 1,272 1,285 1,245 Corporate and other (3),(4) (72 ) (139 ) (212 ) Pretax adjusted earnings (5) 4,461 4,354 4,087 Realized investment gains (losses) (1),(2),(3),(4) (15 ) (297 ) 0 Other income (loss) (6) (1 ) (74 ) (69 ) Total earnings before income taxes $ 4,445 $ 3,983 $ 4,018 Income taxes applicable to pretax adjusted earnings $ 1,147 $ 1,129 $ 1,370 Effect of foreign currency translation on after-tax 15 28 (41 ) (1) Amortized hedge costs of $257 , $236 and $228 in 2019 , 2018 and 2017 , respectively, related to certain foreign currency exposure management strategies have been reclassified from realized investment gains (losses) and reported as a deduction from net investment income when analyzing operations. (2) Net interest cash flows from derivatives associated with certain investment strategies of $(17) in 2019 and an immaterial amount in 2018 have been reclassified from realized investment gains (losses) and included in adjusted earnings as a component of net investment income. (3) Amortized hedge income of $89 in 2019 and $36 in 2018 related to certain foreign currency exposure management strategies has been reclassified from realized investment gains (losses) and reported as an increase to net investment income when analyzing operations. (4) A gain of $66 in 2019 , $67 in 2018 and $77 in 2017 , related to the interest rate component of the change in fair value of foreign currency swaps on notes payable have been reclassified from realized investment gains (losses) and included in adjusted earnings when analyzing operations. (5) Includes $135 , $122 and $122 of interest expense on debt in 2019 , 2018 and 2017 (6) Includes expense of $13 in 2017 for the early extinguishment of debt
Reconciliation of Assets from Segment to Consolidated	Assets as of December 31 were as follows: (In millions) 2019 2018 Assets: Aflac Japan $ 127,523 $ 118,342 Aflac U.S. 20,945 19,100 Corporate and other 4,300 2,964 Total assets $ 152,768 $ 140,406
Foreign Currency Disclosure	Yen-Translation Effects: The following table shows the yen/dollar exchange rates used for or during the periods ended December 31 . Exchange effects were calculated using the same yen/dollar exchange rate for the current year as for each respective prior year. 2019 2018 2017 Statements of Earnings: Weighted-average yen/dollar exchange rate (1) 109.07 110.39 112.16 Yen percent strengthening (weakening) 1.2 % 1.6 % (3.1 )% Exchange effect on pretax adjusted earnings (in millions) $ 20 $ 38 $ (63 ) 2019 2018 Balance Sheets: Yen/dollar exchange rate at December 31 (1) 109.56 111.00 Yen percent strengthening (weakening) 1.3 % 1.8 % Exchange effect on total assets (in millions) $ 1,225 $ 1,362 Exchange effect on total liabilities (in millions) 1,533 1,270 (1) Rates are based on the published MUFG Bank, Ltd. telegraphic transfer middle rate (TTM)
Schedule of Intercompany Transfers of Funds	Information on transfers for each of the years ended December 31 is shown below. See Note 13 for information concerning restrictions on transfers from Aflac Japan. (In millions) 2019 2018 2017 Management fees $ 75 $ 136 $ 93 Allocated expenses 4 24 109 Profit remittances 2,070 808 1,150 Total transfers from Aflac Japan $ 2,149 $ 968 $ 1,352
Property, Plant and Equipment	Classes of property and equipment as of December 31 were as follows: (In millions) 2019 2018 Property and equipment: Land $ 168 $ 168 Buildings 473 456 Equipment and furniture 549 400 Total property and equipment 1,190 1,024 Less accumulated depreciation 609 581 Net property and equipment $ 581 $ 443

INVESTMENTS (Tables)

INVESTMENTS (Tables)	12 Months Ended
INVESTMENTS (Tables)	Dec. 31, 2019
Schedule Of Net Investment Income	The components of net investment income for the years ended December 31 were as follows: (In millions) 2019 2018 2017 Fixed maturity securities $ 3,141 $ 3,142 $ 3,173 Equity securities 37 38 42 Commercial mortgage and other loans 468 333 86 Other investments 53 36 8 Short-term investments and cash equivalents 56 41 25 Gross investment income 3,755 3,590 3,334 Less investment expenses 177 148 114 Net investment income $ 3,578 $ 3,442 $ 3,220
Available-for-Sale Debt Securities	The amortized cost for the Company's investments in fixed maturity securities, the cost for equity securities and the fair values of these investments at December 31 are shown in the following tables. 2019 (In millions) Cost or Gross Gross Fair Securities available for sale, carried at fair value Fixed maturity securities: Yen-denominated: Japan government and agencies $ 30,929 $ 5,169 $ 0 $ 36,098 Municipalities 516 116 3 629 Mortgage- and asset-backed securities 229 25 0 254 Public utilities 1,855 406 0 2,261 Sovereign and supranational 680 50 0 730 Banks/financial institutions 6,152 700 86 6,766 Other corporate 5,323 944 24 6,243 Total yen-denominated 45,684 7,410 113 52,981 U.S. dollar-denominated: U.S. government and agencies 293 9 0 302 Municipalities 1,077 141 0 1,218 Mortgage- and asset-backed securities 149 7 0 156 Public utilities 3,804 725 10 4,519 Sovereign and supranational 239 73 0 312 Banks/financial institutions 2,879 646 4 3,521 Other corporate 25,246 3,255 248 28,253 Total U.S. dollar-denominated 33,687 4,856 262 38,281 Total securities available for sale $ 79,371 $ 12,266 $ 375 $ 91,262 2018 (In millions) Cost or Gross Gross Fair Securities available for sale, carried at fair value Fixed maturity securities: Yen-denominated: Japan government and agencies $ 30,637 $ 3,700 $ 140 $ 34,197 Municipalities 385 32 9 408 Mortgage- and asset-backed securities 155 22 0 177 Public utilities 1,732 280 4 2,008 Sovereign and supranational 826 123 0 949 Banks/financial institutions 5,440 502 238 5,704 Other corporate 4,852 649 44 5,457 Total yen-denominated 44,027 5,308 435 48,900 U.S dollar-denominated: U.S. government and agencies 137 9 1 145 Municipalities 1,343 120 8 1,455 Mortgage- and asset-backed securities 155 8 1 162 Public utilities 4,772 496 105 5,163 Sovereign and supranational 251 60 0 311 Banks/financial institutions 2,860 389 35 3,214 Other corporate 23,311 1,343 1,109 23,545 Total U.S. dollar-denominated 32,829 2,425 1,259 33,995 Total securities available for sale $ 76,856 $ 7,733 $ 1,694 $ 82,895
Held-to-Maturity Securities	2019 (In millions) Cost or Gross Gross Fair Securities held to maturity, carried at amortized cost: Fixed maturity securities: Yen-denominated: Japan government and agencies $ 22,241 $ 6,050 $ 0 $ 28,291 Municipalities 821 262 0 1,083 Mortgage- and asset-backed securities 16 1 0 17 Public utilities 2,535 419 0 2,954 Sovereign and supranational 1,123 197 0 1,320 Banks/financial institutions 916 105 3 1,018 Other corporate 2,433 485 7 2,911 Total yen-denominated 30,085 7,519 10 37,594 Total securities held to maturity $ 30,085 $ 7,519 $ 10 $ 37,594 2018 (In millions) Cost or Gross Gross Fair Securities held to maturity, carried at amortized cost: Fixed maturity securities: Yen-denominated: Japan government and agencies $ 21,712 $ 5,326 $ 0 $ 27,038 Municipalities 359 110 0 469 Mortgage- and asset-backed securities 14 1 0 15 Public utilities 2,727 254 8 2,973 Sovereign and supranational 1,551 289 0 1,840 Banks/financial institutions 1,445 158 20 1,583 Other corporate 2,510 332 38 2,804 Total yen-denominated 30,318 6,470 66 36,722 Total securities held to maturity $ 30,318 $ 6,470 $ 66 $ 36,722
Equity Securities, FV-NI	2019 2018 (In millions) Fair Value Fair Value Equity securities, carried at fair value through net earnings: Equity securities: Yen-denominated $ 658 $ 641 U.S. dollar-denominated 144 346 Total equity securities $ 802 $ 987
Investments Classified by Contractual Maturity Date	The contractual and economic maturities of the Company's investments in fixed maturity securities at December 31, 2019 , were as follows: (In millions) Amortized Fair Available for sale: Due in one year or less $ 583 $ 612 Due after one year through five years 7,933 8,122 Due after five years through 10 years 11,347 12,819 Due after 10 years 59,130 69,299 Mortgage- and asset-backed securities 378 410 Total fixed maturity securities available for sale $ 79,371 $ 91,262 Held to maturity: Due in one year or less $ 265 $ 270 Due after one year through five years 1,227 1,330 Due after five years through 10 years 532 599 Due after 10 years 28,045 35,378 Mortgage- and asset-backed securities 16 17 Total fixed maturity securities held to maturity $ 30,085 $ 37,594
Investment Exposures Exceeding 10 Percent Shareholders Equity	Investment exposures that individually exceeded 10% of shareholders' equity as of December 31 were as follows: 2019 2018 (In millions) Credit Amortized Fair Credit Amortized Fair Japan National Government (1) A+ $51,726 $62,584 A+ $51,207 $59,945 (1) Japan Government Bonds (JGBs) or JGB-backed securities
Gain (Loss) on Investments	Information regarding pretax realized gains and losses from investments for the years ended December 31 follows: (In millions) 2019 2018 2017 Realized investment gains (losses): Fixed maturity securities: Available for sale: Gross gains from sales $ 115 $ 101 $ 51 Gross losses from sales (68 ) (156 ) (68 ) Foreign currency gains (losses) on sales and redemptions (16 ) 73 (48 ) Other-than-temporary impairment losses (13 ) (64 ) (7 ) Total fixed maturity securities 18 (46 ) (72 ) Equity securities 101 (131 ) 71 (1) Loan receivables: Loan loss reserves (18 ) (19 ) (8 ) Total loan receivables (18 ) (19 ) (8 ) Derivatives and other: Derivative gains (losses) (174 ) (224 ) (109 ) Foreign currency gains (losses) (62 ) (10 ) (33 ) Total derivatives and other (236 ) (234 ) (142 ) Total realized investment gains (losses) $ (135 ) $ (430 ) $ (151 ) (1) Includes impairments of $22 in 2017
Unrealized Gain (Loss) on Investments	Information regarding changes in unrealized gains and losses from investments recorded in AOCI for the years ended December 31 follows: (In millions) 2019 2018 2017 Changes in unrealized gains (losses): Fixed maturity securities, available for sale $ 5,852 $ (3,142 ) $ 1,657 Equity securities 0 0 71 Total change in unrealized gains (losses) $ 5,852 $ (3,142 ) $ 1,728
Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities	The net effect on shareholders' equity of unrealized gains and losses from fixed maturity securities at December 31 was as follows: (In millions) 2019 2018 Unrealized gains (losses) on securities available for sale $ 11,891 $ 6,039 Deferred income taxes (3,343 ) (1,805 ) Shareholders’ equity, unrealized gains (losses) on fixed maturity securities $ 8,548 $ 4,234
Investments Gross Unrealized Loss Aging	The following tables show the fair values and gross unrealized losses of the Company's available-for-sale and held-to-maturity investments that were in an unrealized loss position, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at December 31 . 2019 Total Less than 12 months 12 months or longer (In millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturity securities: Municipalities: Yen-denominated $ 80 $ 3 $ 80 $ 3 $ 0 $ 0 Public utilities: U.S. dollar-denominated 306 10 69 2 237 8 Banks/financial institutions: U.S. dollar-denominated 79 4 18 0 61 4 Yen-denominated 1,828 89 1,828 89 0 0 Other corporate: U.S. dollar-denominated 4,261 248 792 53 3,469 195 Yen-denominated 636 31 636 31 0 0 Total $ 7,190 $ 385 $ 3,423 $ 178 $ 3,767 $ 207 2018 Total Less than 12 months 12 months or longer (In millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturity securities: U.S. government and U.S. dollar-denominated $ 67 $ 1 $ 67 $ 1 $ 0 $ 0 Japan government and Yen-denominated 3,604 140 3,604 140 0 0 Municipalities: U.S. dollar-denominated 515 8 515 8 0 0 Yen-denominated 148 9 148 9 0 0 Mortgage- and asset- U.S. dollar-denominated 74 1 74 1 0 0 Public utilities: U.S. dollar-denominated 1,585 105 892 48 693 57 Yen-denominated 604 12 604 12 0 0 Banks/financial institutions: U.S. dollar-denominated 625 35 340 19 285 16 Yen-denominated 3,057 258 3,057 258 0 0 Other corporate: U.S. dollar-denominated 12,899 1,109 5,782 407 7,117 702 Yen-denominated 1,306 82 1,306 82 0 0 Total $ 24,484 $ 1,760 $ 16,389 $ 985 $ 8,095 $ 775
Commercial Mortgage and Other Loans by Property Type	The table below reflects the composition of the carrying value for commercial mortgage and other loans by property type as of December 31. (In millions) 2019 2018 Amortized Cost % of Total Amortized Cost % of Total Commercial Mortgage and other loans Transitional real estate loans: Office $ 1,800 18.7 % $ 1,621 23.3 % Retail 131 1.4 147 2.1 Apartments/Multi-Family 2,085 21.7 1,706 24.6 Industrial 256 2.7 250 3.6 Hospitality 1,036 10.8 531 7.6 Other 164 1.7 139 2.0 Total transitional real estate loans 5,472 57.0 4,394 63.2 Commercial mortgage loans: Office 410 4.3 281 4.1 Retail 348 3.5 316 4.6 Apartments/Multi-Family 569 5.9 369 5.3 Industrial 383 4.0 99 1.4 Total commercial mortgage loans 1,710 17.7 1,065 15.4 Middle market loans 2,432 25.3 1,487 21.4 Total commercial mortgage and other loans $ 9,614 100.0 % $ 6,946 100.0 % Allowance for Loan Losses (45 ) (27 ) Total net commercial mortgage and other loans $ 9,569 $ 6,919
Allowance for Loan Losses by Portfolio Segment	The following table presents the rollforward of the Company's allowance for loan losses by portfolio segment during the year ended December 31. (In millions) Commercial Mortgage Loans Transitional Real Estate Loans Middle Market Loans Total Allowance for loan losses at December 31, 2018 $ (1 ) $ (17 ) $ (9 ) $ (27 ) Addition to (release of) allowance for credit losses (2 ) (5 ) (11 ) (18 ) Allowance for loan losses at December 31, 2019 $ (3 ) $ (22 ) $ (20 ) $ (45 )
Key Credit Quality Indicators for Commercial Mortgage Loans and Transitional Real Estate Loans	The table below summarizes key credit quality information by carrying value for CMLs and TREs as of December 31. 2019 (In millions) Transitional Real Estate Loans Commercial Mortgage Loans Total Loan-to-Value Ratio: 0%-59.99% $ 1,424 $ 1,390 $ 2,814 60%-69.99% 1,927 297 2,224 70%-79.99% 2,085 23 2,108 80% or greater 36 0 36 Total $ 5,472 $ 1,710 $ 7,182 Weighted Average Debt-Service Coverage Ratio 2.38 2018 (In millions) Transitional Real Estate Loans Commercial Mortgage Loans Total Loan-to-Value Ratio: 0%-59.99% $ 819 $ 877 $ 1,696 60%-69.99% 1,681 165 1,846 70%-79.99% 1,558 23 1,581 80% or greater 336 0 336 Total $ 4,394 $ 1,065 $ 5,459 Weighted Average Debt-Service Coverage Ratio 2.45
Other Investments	The table below reflects the composition of the carrying value for other investments as of December 31. (In millions) 2019 2018 Other investments: Policy loans $ 250 $ 232 Short-term investments (1) 628 152 Limited partnerships 569 377 Other 30 26 Total other investments $ 1,477 $ 787 (1)
Securities Lending Transactions Accounted for as Secured Borrowings	Details of collateral by loaned security type and remaining maturity of the agreements as of December 31 were as follows: Securities Lending Transactions Accounted for as Secured Borrowings 2019 Remaining Contractual Maturity of the Agreements (In millions) Overnight (1) Up to 30 Greater Total Securities lending transactions: Fixed maturity securities: Japan government and agencies $ 0 $ 1,013 $ 4,759 $ 5,772 Public utilities 35 0 0 35 Sovereign and supranational 2 0 0 2 Banks/financial institutions 48 0 0 48 Other corporate 778 0 0 778 Equity securities 0 0 0 0 Total borrowings $ 863 $ 1,013 $ 4,759 $ 6,635 Gross amount of recognized liabilities for securities lending transactions $ 1,876 Amounts related to agreements not included in offsetting disclosure in Note 4 $ 4,759 (1) The related loaned security, under the Company's Aflac U.S. securities lending program, can be returned to the Company at the transferee's discretion; therefore, they are classified as Overnight and Continuous. Securities Lending Transactions Accounted for as Secured Borrowings 2018 Remaining Contractual Maturity of the Agreements (In millions) Overnight (1) Up to 30 Greater Total Securities lending transactions: Fixed maturity securities: Japan government and agencies $ 0 $ 387 1,190 $ 1,577 Municipalities 5 0 0 5 Public utilities 27 0 0 27 Banks/financial institutions 74 0 0 74 Other corporate 549 0 0 549 Equity securities 10 0 0 10 Total borrowings $ 665 $ 387 $ 1,190 $ 2,242 Gross amount of recognized liabilities for securities lending transactions $ 1,052 Amounts related to agreements not included in offsetting disclosure in Note 4 $ 1,190 (1) The related loaned security, under the Company's Aflac U.S. securities lending program, can be returned to the Company at the transferee's discretion; therefore, they are classified as Overnight and Continuous
Variable Interest Entity, Consolidated
Investments in Variable Interest Entities	The following table presents the cost or amortized cost, fair value and balance sheet caption in which the assets and liabilities of consolidated VIEs are reported as of December 31. Investments in Consolidated Variable Interest Entities 2019 2018 (In millions) Cost or Amortized Fair Cost or Amortized Fair Assets: Fixed maturity securities, available for sale $ 3,308 $ 4,312 $ 3,849 $ 4,466 Equity securities 0 0 160 160 Commercial mortgage and other loans 7,956 8,015 5,528 5,506 Other investments (1) 494 494 328 328 Other assets (2) 169 169 182 182 Total assets of consolidated VIEs $ 11,927 $ 12,990 $ 10,047 $ 10,642 Liabilities: Other liabilities (2) $ 126 $ 126 $ 102 $ 102 Total liabilities of consolidated VIEs $ 126 $ 126 $ 102 $ 102 (1) Consists entirely of alternative investments in limited partnerships (2) Consists entirely of derivatives
Variable Interest Entity, Not Consolidated
Investments in Variable Interest Entities	The table below reflects the amortized cost, fair value and balance sheet caption in which the Company's investment in VIEs not consolidated are reported as of December 31. Investments in Variable Interest Entities Not Consolidated 2019 2018 (In millions) Amortized Fair Amortized Fair Assets: Fixed maturity securities, available for sale $ 4,129 $ 4,884 $ 4,575 $ 4,982 Fixed maturity securities, held to maturity 1,848 2,236 2,007 2,254 Other investments (1) 75 74 49 49 Total investments in VIEs not consolidated $ 6,052 $ 7,194 $ 6,631 $ 7,285 (1) Consists entirely of alternative investments in limited partnerships

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	12 Months Ended
DERIVATIVE INSTRUMENTS (Tables)	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	2019 2018 (In millions) Asset Liability Asset Liability Hedge Designation/ Derivative Notional Fair Value Fair Value Notional Fair Value Fair Value Cash flow hedges: Foreign currency swaps - VIE $ 75 $ 0 $ 8 $ 75 $ 1 $ 4 Total cash flow hedges 75 0 8 75 1 4 Fair value hedges: Foreign currency forwards 964 0 38 2,086 0 34 Foreign currency options 11,573 0 5 9,070 3 1 Interest rate swaptions 243 0 0 500 0 1 Total fair value hedges 12,780 0 43 11,656 3 36 Net investment hedge: Foreign currency forwards 4,952 72 2 0 0 0 Foreign currency options 2,000 0 0 0 0 0 Total net investment hedge 6,952 72 2 0 0 0 Non-qualifying strategies: Foreign currency swaps 2,800 72 78 2,800 103 129 Foreign currency swaps - VIE 2,587 169 118 2,587 181 101 Foreign currency forwards 19,821 166 337 16,057 126 117 Foreign currency options 9,553 0 0 430 0 0 Interest rate swaps 7,120 3 0 4,750 3 0 Interest rate swaptions 7 0 0 0 0 0 Total non-qualifying strategies 41,888 410 533 26,624 413 347 Total derivatives $ 61,695 $ 482 $ 586 $ 38,355 $ 417 $ 387
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location	The following table presents the gains and losses on derivatives and the related hedged items in fair value hedges for the years ended December 31. Fair Value Hedging Relationships (In millions) Hedging Derivatives Hedged Items Hedging Derivatives Hedged Items Total Gains (Losses) (1) Gains (Losses) (2) Gains (Losses) (2) Net Realized Gains (Losses) Recognized for Fair Value Hedge 2019: Foreign currency Fixed maturity securities $ (50 ) $ (64 ) $ 14 $ (12 ) $ 2 Foreign currency Fixed maturity securities (7 ) (7 ) 0 0 0 Interest rate Fixed maturity securities (9 ) (9 ) 0 0 0 Total gains (losses) $ (66 ) $ (80 ) $ 14 $ (12 ) $ 2 2018: Foreign currency forwards Fixed maturity securities $ 126 $ (104 ) $ 230 $ (242 ) $ (12 ) Foreign currency options Fixed maturity securities 4 4 0 0 0 Interest rate Fixed maturity securities (1 ) (1 ) 0 0 0 Total gains (losses) $ 129 $ (101 ) $ 230 $ (242 ) $ (12 ) 2017: Foreign currency forwards Fixed maturity and equity securities $ 98 $ (202 ) $ 300 $ (278 ) $ 22 Foreign currency options Fixed maturity securities 21 10 11 (10 ) 1 Total gains (losses) $ 119 $ (192 ) $ 311 $ (288 ) $ 23 (1) Gains (losses) excluded from effectiveness testing includes the forward point on foreign currency forwards and time value change on foreign currency options which are reported in the consolidated statement of earnings as realized investment gains (losses). It also includes the change in the fair value of the interest rate swaptions related to the time value of the swaptions which is recognized as a component of other comprehensive income (loss). (2) Gains and losses on foreign currency forwards and options and related hedged items are reported in the consolidated statement of earnings as realized investment gains (losses). For interest rate swaptions and related hedged items, gains and losses included in the hedge assessment, premium amortization and time value amortization while the hedge items are still outstanding are reported within net investment income. The time value gains and losses for interest rate swaptions when the related hedged items are redeemed are reported in realized investment gains and losses consistent with the impact of the hedged item. For the years ended December 31, 2019 and 2018, gains and losses included in the hedge assessment on interest rate swaptions and related hedged items were immaterial.
Schedule of Interest Rate Fair Value Hedges Hedged Items	The following table shows the carrying amounts of assets designated and qualifying as hedged items in fair value hedges of interest rate risk and the related cumulative hedge adjustment included in the carrying amount as of December 31. (In millions) Carrying Amount of the Hedged Assets/(Liabilities) (1) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Assets/(Liabilities) 2019 2018 2019 2018 Fixed maturity securities $ 4,633 $ 6,593 $ 256 $ 294 (1) The balance includes hedging adjustment on discontinued hedging relationships of $256 in 2019 and $294 in 2018 . The total notional amount of the Company's interest rate swaptions was $243 in 2019 and $500 in 2018 . The hedging adjustment related to these derivatives was immaterial.
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table summarizes the impact to realized investment gains (losses) and other comprehensive income (loss) from all derivatives and hedging instruments for the years ended December 31. 2019 2018 2017 (In millions) Net Investment Income (1) Realized Investment Other (2) Net Investment Income (1) Realized Investment Other (2) Net Investment Income (1) Realized Other (2) Qualifying hedges: Cash flow hedges: Foreign currency swaps - VIE $ (2 ) $ (1 ) $ (4 ) $ 0 $ 0 $ 3 $ 0 $ 0 $ 1 Total cash flow hedges (2 ) (1 ) (3) (4 ) 0 0 (3) 3 0 0 (3) 1 Fair value hedges: Foreign currency forwards (3) (62 ) (116 ) (180 ) Foreign currency options (3) (7 ) 4 11 Interest rate swaptions (3) (1 ) 0 (8 ) 0 0 (1 ) 0 0 0 Total fair value hedges (1 ) (69 ) (8 ) 0 (112 ) (1 ) 0 (169 ) 0 Net investment hedge: Non-derivative hedging 0 (24 ) 0 (32 ) 0 (15 ) Foreign currency forwards 10 83 0 0 0 (25 ) Foreign currency options (4 ) 0 0 (8 ) 0 5 Total net investment hedge 6 59 0 (40 ) 0 (35 ) Non-qualifying strategies: Foreign currency swaps 90 (40 ) 9 Foreign currency swaps - VIE (68 ) 60 44 Foreign currency forwards (148 ) (135 ) 8 Credit default swaps 0 0 (1 ) Interest rate swaps 17 3 0 Total non-qualifying strategies (110 ) (112 ) 60 Total $ (3 ) $ (174 ) $ 47 $ 0 $ (224 ) $ (38 ) $ 0 $ (109 ) $ (34 ) (1) Cash flow hedge items and the change in the fair value of interest rate swaptions related to the time value of the swaptions in fair value hedges are recorded as unrealized gains (losses) on derivatives and net investment hedge items are recorded in the unrealized foreign currency translation gains (losses) line in the consolidated statement of comprehensive income (loss). (2) Impact of cash flow hedges reported as realized investment gains (losses) includes an immaterial amount of gains or losses reclassified from accumulated other comprehensive income (loss) into earnings. It also includes an immaterial amount excluded from effectiveness testing during the years ended December 31, 2019 , 2018 and 2017 , respectively. (3) Impact shown net of effect of hedged items (see Fair Value Hedges section of this Note 4 for further detail)
Offsetting Assets	Offsetting of Financial Assets and Derivative Assets 2019 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Assets Gross Amount Offset in Balance Sheet Net Amount of Assets Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Received Net Amount Derivative assets: Derivative assets subject to a master netting agreement or offsetting arrangement OTC - bilateral $ 310 $ 0 $ 310 $ (190 ) $ (7 ) $ (113 ) $ 0 OTC - cleared 3 0 3 0 0 0 3 Total derivative 313 0 313 (190 ) (7 ) (113 ) 3 Derivative assets not subject to a master netting agreement or offsetting arrangement OTC - bilateral 169 169 169 Total derivative 169 169 169 Total derivative assets 482 0 482 (190 ) (7 ) (113 ) 172 Securities lending and similar arrangements 1,860 0 1,860 0 0 (1,860 ) 0 Total $ 2,342 $ 0 $ 2,342 $ (190 ) $ (7 ) $ (1,973 ) $ 172 2018 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Assets Gross Amount Offset in Balance Sheet Net Amount of Assets Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Received Net Amount Derivative assets: Derivative assets subject to a master netting agreement or offsetting arrangement OTC - bilateral $ 231 $ 0 $ 231 $ (152 ) $ (23 ) $ (55 ) $ 1 OTC - cleared 3 0 3 0 0 (3 ) 0 Total derivative 234 0 234 (152 ) (23 ) (58 ) 1 Derivative assets not subject to a master netting agreement or offsetting arrangement OTC - bilateral 183 183 183 Total derivative 183 183 183 Total derivative assets 417 0 417 (152 ) (23 ) (58 ) 184 Securities lending and similar arrangements 1,029 0 1,029 0 0 (1,029 ) 0 Total $ 1,446 $ 0 $ 1,446 $ (152 ) $ (23 ) $ (1,087 ) $ 184
Offsetting Liabilities	Offsetting of Financial Liabilities and Derivative Liabilities 2019 Gross Amounts Not Offset in Balance Sheet (In millions) Gross Amount of Recognized Liabilities Gross Amount Offset in Balance Sheet Net Amount of Liabilities Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Pledged Net Amount Derivative liabilities: Derivative liabilities subject to a master netting agreement or offsetting arrangement OTC - bilateral $ 459 $ 0 $ 459 $ (190 ) $ (222 ) $ (32 ) $ 15 OTC - cleared 1 0 1 0 0 (1 ) 0 Total derivative 460 0 460 (190 ) (222 ) (33 ) 15 Derivative liabilities not subject to a master netting agreement or offsetting arrangement OTC - bilateral 126 126 126 Total derivative 126 126 126 Total derivative liabilities 586 0 586 (190 ) (222 ) (33 ) 141 Securities lending and similar arrangements 1,876 0 1,876 (1,860 ) 0 0 16 Total $ 2,462 $ 0 $ 2,462 $ (2,050 ) $ (222 ) $ (33 ) $ 157 2018 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Liabilities Gross Amount Offset in Balance Sheet Net Amount of Liabilities Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Pledged Net Amount Derivative liabilities: Derivative liabilities subject to a master netting agreement or offsetting arrangement OTC - bilateral $ 285 $ 0 $ 285 $ (152 ) $ (37 ) $ (68 ) $ 28 Total derivative 285 0 285 (152 ) (37 ) (68 ) 28 Derivative liabilities not subject to a master netting agreement or offsetting arrangement OTC - bilateral 102 102 102 Total derivative 102 102 102 Total derivative liabilities 387 0 387 (152 ) (37 ) (68 ) 130 Securities lending and similar arrangements 1,052 0 1,052 (1,029 ) 0 0 23 Total $ 1,439 $ 0 $ 1,439 $ (1,181 ) $ (37 ) $ (68 ) $ 153

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
FAIR VALUE MEASUREMENTS (Tables)	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Hierarchy, Assets and Liabilities Measured on Recurring Basis	The following tables present the fair value hierarchy levels of the Company's assets and liabilities that are measured and carried at fair value on a recurring basis as of December 31. 2019 (In millions) Quoted Prices in Significant Significant Total Assets: Securities available for sale, carried at Fixed maturity securities: Government and agencies $ 34,878 $ 1,522 $ 0 $ 36,400 Municipalities 0 1,847 0 1,847 Mortgage- and asset-backed securities 0 232 178 410 Public utilities 0 6,556 224 6,780 Sovereign and supranational 0 1,042 0 1,042 Banks/financial institutions 0 10,264 23 10,287 Other corporate 0 34,234 262 34,496 Total fixed maturity securities 34,878 55,697 687 91,262 Equity securities 642 80 80 802 Other investments 628 0 0 628 Cash and cash equivalents 4,896 0 0 4,896 Other assets: Foreign currency swaps 0 72 169 241 Foreign currency forwards 0 238 0 238 Interest rate swaps 0 3 0 3 Total other assets 0 313 169 482 Total assets $ 41,044 $ 56,090 $ 936 $ 98,070 Liabilities: Other liabilities: Foreign currency swaps $ 0 $ 78 $ 126 $ 204 Foreign currency forwards 0 377 0 377 Foreign currency options 0 5 0 5 Total liabilities $ 0 $ 460 $ 126 $ 586 2018 (In millions) Quoted Prices in Significant Significant Total Assets: Securities available for sale, carried at Fixed maturity securities: Government and agencies $ 32,993 $ 1,349 $ 0 $ 34,342 Municipalities 0 1,863 0 1,863 Mortgage- and asset-backed securities 0 162 177 339 Public utilities 0 7,062 109 7,171 Sovereign and supranational 0 1,260 0 1,260 Banks/financial institutions 0 8,895 23 8,918 Other corporate 0 28,789 213 29,002 Total fixed maturity securities 32,993 49,380 522 82,895 Equity securities 874 67 46 987 Other investments 152 0 0 152 Cash and cash equivalents 4,337 0 0 4,337 Other assets: Foreign currency swaps 0 103 182 285 Foreign currency forwards 0 126 0 126 Foreign currency options 0 3 0 3 Interest rate swaps 0 3 0 3 Total other assets 0 235 182 417 Total assets $ 38,356 $ 49,682 $ 750 $ 88,788 Liabilities: Other liabilities: Foreign currency swaps $ 0 $ 132 $ 102 $ 234 Foreign currency forwards 0 151 0 151 Foreign currency options 0 1 0 1 Interest rate swaptions 0 1 0 1 Total liabilities $ 0 $ 285 $ 102 $ 387
Fair Value Hierarchy Levels of Assets and Liabilities Carried at Cost or Amortized Cost	The following tables present the carrying amount and fair value categorized by fair value hierarchy level for the Company's financial instruments that are not carried at fair value as of December 31. 2019 (In millions) Carrying Quoted Prices in Significant Significant Total Assets: Securities held to maturity, Fixed maturity securities: Government and agencies $ 22,241 $ 27,937 $ 354 $ 0 $ 28,291 Municipalities 821 0 1,083 0 1,083 Mortgage and asset-backed 16 0 7 10 17 Public utilities 2,535 0 2,954 0 2,954 Sovereign and 1,123 0 1,320 0 1,320 Banks/financial institutions 916 0 1,018 0 1,018 Other corporate 2,433 0 2,911 0 2,911 Commercial mortgage and 9,569 0 0 9,648 9,648 Other investments (1) 30 0 30 0 30 Total assets $ 39,684 $ 27,937 $ 9,677 $ 9,658 $ 47,272 Liabilities: Other policyholders’ funds $ 7,317 $ 0 $ 0 $ 7,234 $ 7,234 Notes payable 6,408 0 6,663 272 6,935 Total liabilities $ 13,725 $ 0 $ 6,663 $ 7,506 $ 14,169 (1) Excludes policy loans of $250 and equity method investments of $569 , at carrying value 2018 (In millions) Carrying Quoted Prices in Significant Significant Total Assets: Securities held to maturity, Fixed maturity securities: Government and agencies $ 21,712 $ 27,030 $ 8 $ 0 $ 27,038 Municipalities 359 0 469 0 469 Mortgage and asset-backed 14 0 0 15 15 Public utilities 2,727 0 2,973 0 2,973 Sovereign and 1,551 0 1,840 0 1,840 Banks/financial institutions 1,445 0 1,583 0 1,583 Other corporate 2,510 0 2,804 0 2,804 Commercial mortgage and 6,919 0 0 6,893 6,893 Other investments (1) 26 0 26 0 26 Total assets $ 37,263 $ 27,030 $ 9,703 $ 6,908 $ 43,641 Liabilities: Other policyholders’ funds $ 7,146 $ 0 $ 0 $ 7,067 $ 7,067 Notes payable 5,765 0 5,606 270 5,876 Total liabilities $ 12,911 $ 0 $ 5,606 $ 7,337 $ 12,943 (1) Excludes policy loans of $232 and equity method investments of $377 , at carrying value
Fair Value Assets Securities Carried At Fair Value Primary Pricing Sources	The following tables present the pricing sources for the fair values of the Company's fixed maturity and equity securities as of December 31. 2019 (In millions) Quoted Prices in Active Markets for Identical Assets Significant Observable Inputs Significant Unobservable Inputs Total Securities available for sale, carried at fair value: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 34,878 $ 1,522 $ 0 $ 36,400 Total government and agencies 34,878 1,522 0 36,400 Municipalities: Third party pricing vendor 0 1,847 0 1,847 Total municipalities 0 1,847 0 1,847 Mortgage- and asset-backed securities: Third party pricing vendor 0 232 0 232 Broker/other 0 0 178 178 Total mortgage- and asset-backed securities 0 232 178 410 Public utilities: Third party pricing vendor 0 6,556 0 6,556 Broker/other 0 0 224 224 Total public utilities 0 6,556 224 6,780 Sovereign and supranational: Third party pricing vendor 0 1,042 0 1,042 Total sovereign and supranational 0 1,042 0 1,042 Banks/financial institutions: Third party pricing vendor 0 10,264 0 10,264 Broker/other 0 0 23 23 Total banks/financial institutions 0 10,264 23 10,287 Other corporate: Third party pricing vendor 0 34,234 0 34,234 Broker/other 0 0 262 262 Total other corporate 0 34,234 262 34,496 Total securities available for sale $ 34,878 $ 55,697 $ 687 $ 91,262 Equity securities, carried at fair value: Third party pricing vendor $ 642 $ 80 $ 0 $ 722 Broker/other 0 0 80 80 Total equity securities $ 642 $ 80 $ 80 $ 802 2018 (In millions) Quoted Prices in Active Markets Significant Observable Significant Unobservable Inputs Total Securities available for sale, carried at fair value: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 32,993 $ 1,349 $ 0 $ 34,342 Total government and agencies 32,993 1,349 0 34,342 Municipalities: Third party pricing vendor 0 1,863 0 1,863 Total municipalities 0 1,863 0 1,863 Mortgage- and asset-backed securities: Third party pricing vendor 0 162 0 162 Broker/other 0 0 177 177 Total mortgage- and asset-backed securities 0 162 177 339 Public utilities: Third party pricing vendor 0 7,062 0 7,062 Broker/other 0 0 109 109 Total public utilities 0 7,062 109 7,171 Sovereign and supranational: Third party pricing vendor 0 1,260 0 1,260 Total sovereign and supranational 0 1,260 0 1,260 Banks/financial institutions: Third party pricing vendor 0 8,895 0 8,895 Broker/other 0 0 23 23 Total banks/financial institutions 0 8,895 23 8,918 Other corporate: Third party pricing vendor 0 28,789 0 28,789 Broker/other 0 0 213 213 Total other corporate 0 28,789 213 29,002 Total securities available for sale $ 32,993 $ 49,380 $ 522 $ 82,895 Equity securities, carried at fair value: Third party pricing vendor $ 874 $ 67 $ 0 $ 941 Broker/other 0 0 46 46 Total equity securities $ 874 $ 67 $ 46 $ 987
Fair Value Assets Held-To-Maturity Securities Primary Pricing Sources	2019 (In millions) Quoted Prices in Active Markets for Identical Assets Significant Observable Inputs Significant Unobservable Inputs Total Securities held to maturity, carried at amortized cost: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 27,937 $ 354 $ 0 $ 28,291 Total government and agencies 27,937 354 0 28,291 Municipalities: Third party pricing vendor 0 1,083 0 1,083 Total municipalities 0 1,083 0 1,083 Mortgage- and asset-backed securities: Third party pricing vendor 0 7 0 7 Broker/other 0 0 10 10 Total mortgage- and asset-backed securities 0 7 10 17 Public utilities: Third party pricing vendor 0 2,954 0 2,954 Total public utilities 0 2,954 0 2,954 Sovereign and supranational: Third party pricing vendor 0 1,320 0 1,320 Total sovereign and supranational 0 1,320 0 1,320 Banks/financial institutions: Third party pricing vendor 0 1,018 0 1,018 Total banks/financial institutions 0 1,018 0 1,018 Other corporate: Third party pricing vendor 0 2,911 0 2,911 Total other corporate 0 2,911 0 2,911 Total securities held to maturity $ 27,937 $ 9,647 $ 10 $ 37,594 2018 (In millions) Quoted Prices in Active Markets Significant Observable Significant Unobservable Inputs Total Securities held to maturity, carried at amortized cost: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 27,030 $ 8 $ 0 $ 27,038 Total government and agencies 27,030 8 0 27,038 Municipalities: Third party pricing vendor 0 469 0 469 Total municipalities 0 469 0 469 Mortgage- and asset-backed securities: Broker/other 0 0 15 15 Total mortgage- and asset-backed securities 0 0 15 15 Public utilities: Third party pricing vendor 0 2,973 0 2,973 Total public utilities 0 2,973 0 2,973 Sovereign and supranational: Third party pricing vendor 0 1,840 0 1,840 Total sovereign and supranational 0 1,840 0 1,840 Banks/financial institutions: Third party pricing vendor 0 1,583 0 1,583 Total banks/financial institutions 0 1,583 0 1,583 Other corporate: Third party pricing vendor 0 2,804 0 2,804 Total other corporate 0 2,804 0 2,804 Total securities held to maturity $ 27,030 $ 9,677 $ 15 $ 36,722
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	The following tables present the changes in fair value of the Company's investments and derivatives carried at fair value classified as Level 3 as of December 31. 2019 Fixed Maturity Securities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 177 $ 109 $ 23 $ 213 $ 46 $ 80 $ 0 $ 648 Realized investment gains (losses) included 0 0 0 (1 ) 0 (33 ) 0 (34 ) Unrealized gains (losses) included in other 1 6 1 8 0 (4 ) 0 12 Purchases, issuances, sales and settlements: Purchases 0 48 0 165 34 0 0 247 Issuances 0 0 0 0 0 0 0 0 Sales 0 (24 ) 0 (17 ) 0 0 0 (41 ) Settlements 0 (6 ) 0 0 0 0 0 (6 ) Transfers into Level 3 0 116 (2) 0 26 (2) 0 0 0 142 Transfers out of Level 3 0 (25 ) (2) (1 ) (132 ) (2), (3) 0 0 0 (158 ) Balance, end of period $ 178 $ 224 $ 23 $ 262 $ 80 $ 43 $ 0 $ 810 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ (33 ) $ 0 $ (33 ) (1) Derivative assets and liabilities are presented net (2) Transfer due to sector classification change (3) Transfer due to availability of observable market inputs 2018 Fixed Maturity Securities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 175 $ 68 $ 25 $ 146 $ 16 $ 22 $ 1 $ 453 Realized investment gains (losses) included in 0 0 0 0 (1 ) 54 (1 ) 52 Unrealized gains (losses) included in other 2 1 (2 ) 1 0 4 0 6 Purchases, issuances, sales and settlements: Purchases 0 40 0 56 31 0 0 127 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 0 0 0 0 Settlements 0 0 0 (6 ) 0 0 0 (6 ) Transfers into Level 3 0 0 0 16 0 0 0 16 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 177 $ 109 $ 23 $ 213 $ 46 $ 80 $ 0 $ 648 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ (1 ) $ 54 $ (1 ) $ 52 (1) Derivative assets and liabilities are presented net
Fair Value Measurement Inputs and Valuation Techniques	Level 3 Significant Unobservable Input Sensitivity The following tables summarize the significant unobservable inputs used in the valuation of the Company's Level 3 investments and derivatives carried at fair value as of December 31. Included in the tables are the inputs or range of possible inputs that have an effect on the overall valuation of the financial instruments. 2019 (In millions) Fair Value Valuation Technique(s) Unobservable Input Range Assets: Securities available for sale, carried at fair value: Fixed maturity securities: Mortgage- and asset-backed securities $ 178 Consensus pricing Offered quotes N/A (a) Public utilities 224 Discounted cash flow Credit spreads N/A (a) Banks/financial institutions 23 Consensus pricing Offered quotes N/A (a) Other corporate 262 Discounted cash flow Credit spreads N/A (a) Equity securities 80 Net asset value Offered quotes N/A (a) Other assets: Foreign currency swaps 106 Discounted cash flow Interest rates (USD) 1.89% - 2.09% (b) Interest rates (JPY) .12% - .43% (c) CDS spreads 10 - 100 bps 63 Discounted cash flow Interest rates (USD) 1.89% - 2.09% (b) Interest rates (JPY) .12% - .43% (c) Total assets $ 936 Liabilities: Other liabilities: Foreign currency swaps $ 118 Discounted cash flow Interest rates (USD) 1.89% - 2.09% (b) Interest rates (JPY) .12% - .43% (c) CDS spreads 13 - 159 bps 8 Discounted cash flow Interest rates (USD) 1.89% - 2.09% (b) Interest rates (JPY) .12% - .43% (c) Total liabilities $ 126 (a) N/A represents securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques or unobservable inputs. (b) Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps (c) Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps 2018 (In millions) Fair Value Valuation Technique(s) Unobservable Input Range Assets: Securities available for sale, carried at fair value: Fixed maturity securities: Mortgage- and asset-backed securities $ 177 Consensus pricing Offered quotes N/A (a) Public utilities 109 Discounted cash flow Credit spreads N/A (a) Banks/financial institutions 23 Consensus pricing Offered quotes N/A (a) Other corporate 213 Discounted cash flow Credit spreads N/A (a) Equity securities 46 Net asset value Offered quotes N/A (a) Other assets: Foreign currency swaps 125 Discounted cash flow Interest rates (USD) 2.75% - 2.84% (b) Interest rates (JPY) .18% - .71% (c) CDS spreads 19 - 120 bps 57 Discounted cash flow Interest rates (USD) 2.75% - 2.84% (b) Interest rates (JPY) .18% - .71% (c) Total assets $ 750 Liabilities: Other liabilities: Foreign currency swaps $ 98 Discounted cash flow Interest rates (USD) 2.75% - 2.84% (b) Interest rates (JPY) .18% - .71% (c) CDS spreads 28 - 211 bps 4 Discounted cash flow Interest rates (USD) 2.75% - 2.84% (b) Interest rates (JPY) .18% - .71% (c) Total liabilities $ 102 (a) N/A represents securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques or unobservable inputs. (b) Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps (c) Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps

DEFERRED POLICY ACQUISITION C_2

DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2019
Deferred Policy Acquisition Costs Disclosures [Abstract]
Schedule of Deferred Policy Acquisition Costs	The following table presents a rollforward of deferred policy acquisition costs by segment for the years ended December 31. 2019 2018 (In millions) Japan U.S. Japan U.S. Deferred policy acquisition costs: Balance, beginning of year $ 6,384 $ 3,491 $ 6,150 $ 3,355 Capitalization 825 626 833 669 Amortization (709 ) (573 ) (710 ) (534 ) Foreign currency translation and other 84 0 111 1 Balance, end of year $ 6,584 $ 3,544 $ 6,384 $ 3,491
Advertising Expense	Advertising expense, which is included in insurance expenses in the consolidated statements of earnings, was as follows for the years ended December 31: (In millions) 2019 2018 2017 Advertising expense: Aflac Japan $ 101 $ 108 $ 100 Aflac U.S. 118 110 110 Total advertising expense $ 219 $ 218 $ 210
Schedule Of Depreciation And Amortization Expense	Depreciation and other amortization expenses, which are included in insurance expenses in the consolidated statements of earnings, were as follows for the years ended December 31: (In millions) 2019 2018 2017 Depreciation expense $ 40 $ 48 $ 50 Other amortization expense 1 1 3 Total depreciation and other amortization expense $ 41 $ 49 $ 53

POLICY LIABILITIES (Tables)

POLICY LIABILITIES (Tables)	12 Months Ended
POLICY LIABILITIES (Tables)	Dec. 31, 2019
Insurance Loss Reserves [Abstract]
Liability for Future Policy Benefits by Product Segment	The liability for future policy benefits as of December 31 consisted of the following: Liability Amounts Interest Rate Assumptions (In millions) 2019 2018 Health insurance Japan $ 50,941 $ 49,496 0.6 - 6.75 % U.S. 8,646 8,442 3.0 - 7.0 Intercompany eliminations (532 ) (1) (583 ) (1) 2.0 Life insurance Japan 30,520 28,318 1.0 - 4.5 U.S. 760 695 2.5 - 6.0 Total $ 90,335 $ 86,368 (1) Elimination entry necessary due to recapture of a portion of policy liabilities ceded externally, as a result of the reinsurance retrocession transaction as described in Note 8 of the Notes to the Consolidated Financial Statements
Schedule of Liability for Unpaid Claims Adjustment Expense	Changes in the liability for unpaid policy claims were as follows for the years ended December 31: (In millions) 2019 2018 2017 Unpaid supplemental health claims, beginning of period $ 3,952 $ 3,884 $ 3,707 Less reinsurance recoverables 27 30 27 Net balance, beginning of period 3,925 3,854 3,680 Add claims incurred during the period related to: Current year 7,216 7,101 6,979 Prior years (552 ) (563 ) (518 ) Total incurred 6,664 6,538 6,461 Less claims paid during the period on claims incurred during: Current year 4,715 4,612 4,530 Prior years 1,965 1,898 1,822 Total paid 6,680 6,510 6,352 Effect of foreign exchange rate changes on unpaid claims 29 43 65 Net balance, end of period 3,938 3,925 3,854 Add reinsurance recoverables 30 27 30 Unpaid supplemental health claims, end of period 3,968 3,952 3,884 Unpaid life claims, end of period 691 632 508 Total liability for unpaid policy claims $ 4,659 $ 4,584 $ 4,392

REINSURANCE (Tables)

REINSURANCE (Tables)	12 Months Ended
REINSURANCE (Tables)	Dec. 31, 2019
Reinsurance Disclosures [Abstract]
Effects of Reinsurance	The following table reconciles direct premium income and direct benefits and claims to net amounts after the effect of reinsurance for the years ended December 31. (In millions) 2019 2018 2017 Direct premium income $ 19,122 $ 19,018 $ 18,875 Ceded to other companies: Ceded Aflac Japan closed blocks (478 ) (497 ) (515 ) Other (69 ) (58 ) (51 ) Assumed from other companies: Retrocession activities 200 208 216 Other 5 6 6 Net premium income $ 18,780 $ 18,677 $ 18,531 Direct benefits and claims $ 12,237 $ 12,293 $ 12,486 Ceded benefits and change in reserves for future benefits: Ceded Aflac Japan closed blocks (433 ) (450 ) (473 ) Eliminations 41 43 51 Other (57 ) (44 ) (44 ) Assumed from other companies: Retrocession activities 194 209 209 Eliminations (41 ) (53 ) (51 ) Other 1 2 3 Benefits and claims, net $ 11,942 $ 12,000 $ 12,181

NOTES PAYABLE (Tables)

NOTES PAYABLE (Tables)	12 Months Ended
NOTES PAYABLE (Tables)	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	A summary of notes payable and lease obligations as of December 31 follows: (In millions) 2019 2018 4.00% senior notes due February 2022 (1) $ 348 $ 348 3.625% senior notes due June 2023 698 698 3.625% senior notes due November 2024 747 746 3.25% senior notes due March 2025 448 447 2.875% senior notes due October 2026 298 297 6.90% senior notes due December 2039 220 220 6.45% senior notes due August 2040 254 254 4.00% senior notes due October 2046 394 394 4.750% senior notes due January 2049 541 540 Yen-denominated senior notes and subordinated debentures: .932% senior notes due January 2027 (principal amount ¥60.0 billion) 545 538 .500% senior notes due December 2029 (principal amount ¥12.6 billion) 114 0 1.159% senior notes due October 2030 (principal amount ¥29.3 billion) 266 262 .843% senior notes due December 2031 (principal amount ¥9.3 billion) 84 0 1.488% senior notes due October 2033 (principal amount ¥15.2 billion) 138 136 .934% senior notes due December 2034 (principal amount ¥9.8 billion) 88 0 1.750% senior notes due October 2038 (principal amount ¥8.9 billion) 81 79 1.122% senior notes due December 2039 (principal amount ¥6.3 billion) 57 0 2.108% subordinated debentures due October 2047 (principal amount ¥60.0 billion) 543 536 .963% subordinated bonds due April 2049 (principal amount ¥30.0 billion) 272 0 Yen-denominated loans: Variable interest rate loan due September 2026 (.42% in 2019 and .32% in 2018, principal amount ¥5.0 billion) 45 45 Variable interest rate loan due September 2029 (.57% in 2019 and .47% in 2018, principal amount ¥25.0 billion) 227 225 Finance lease obligations payable through 2026 12 13 Operating lease obligations payable through 2049 (2) 149 0 Total notes payable and lease obligations $ 6,569 $ 5,778 (1) Redeemed in January 2020 (2) See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2019 related to leases. Amounts in the table above are reported net of debt issuance costs and issuance premiums or discounts, if applicable, that are being amortized over the life of the notes.
Schedule of Maturities of Long Term Debt	The aggregate contractual maturities of notes payable during each of the years after December 31, 2019 , are as follows: (In millions) Total 2020 $ 0 2021 0 2022 350 2023 700 2024 750 Thereafter 4,658 Total $ 6,458
Schedule of Lease Maturities	The following table presents the contractual maturities and present value of lease liabilities as of December 31. 2019 (In millions) Operating Leases Finance Leases Total 2020 $ 49 $ 4 $ 53 2021 37 3 40 2022 31 2 33 2023 10 2 12 2024 10 1 11 After 2024 22 0 22 Total lease payments $ 159 $ 12 $ 171 Less: Interest 10 0 10 Present value of lease liabilities $ 149 $ 12 $ 161
Lease, Cost	The following table presents the weighted average remaining lease term and weighted average discount rate for lease liabilities as of December 31. 2019 Weighted average remaining lease term (years): Operating leases 6.8 Finance leases 3.7 Weighted average discount rate: Operating leases 2.1% Finance leases 1.5%
Schedule of Line of Credit Facilities	A summary of the Company's lines of credit as of December 31, 2019 follows: Borrower Type Original Term Expiration Date Capacity Amount Outstanding Interest Rate on Borrowed Amount Maturity Period Commitment Fee Business Purpose Aflac Incorporated uncommitted bilateral 364 days December 18, 2020 $100 million $0 million The rate quoted by the bank and agreed upon at the time of borrowing Up to 3 months None General corporate purposes Aflac Incorporated unsecured revolving 5 years March 29, ¥100.0 billion ¥0.0 billion A rate per annum equal to (a) Tokyo interbank market rate (TIBOR) plus, the alternative applicable TIBOR margin during the availability period from the closing date to the commitment termination date or (b) the TIBOR rate offered by the agent to major banks in yen for the applicable period plus, the applicable alternative TIBOR margin during the term out period No later than .30% to .50%, depending on the Parent Company's debt ratings as of the date of determination General corporate purposes, including a capital contingency plan for the operations of the Parent Company Aflac Incorporated unsecured revolving 5 years November 18, 2024, or the date commitments are terminated pursuant to an event of default $1.0 billion $0.0 billion A rate per annum equal to, at the Company's option, either, (a) the rate for Eurocurrency for deposits in the London interbank market for a period of one, two, three or six months (LIBOR) or (b) a base rate determined by reference to the highest of (1) the federal funds rate plus 1/2 of 1%, (2) the rate of interest in effect for such day as publicly announced from time to time by Mizuho as its “prime rate”, and (3) the LIBOR for a one month interest period in effect on such day (or if such day is not a business day, the immediately preceding business day) plus 1.00%, and in each case an applicable margin No later than November 18, 2024 .085% to General corporate purposes, including a capital contingency plan for the operations of the Parent Company Aflac Incorporated uncommitted bilateral None specified None specified $50 million $0 million A rate per annum equal to, at the Parent Company's option, either (a) a eurocurrency rate determined by reference to the agent's LIBOR for the interest period relevant to such borrowing or (b) the base rate determined by reference to the greater of (i) the prime rate as determined by the agent, and (ii) the sum of 0.50% and the federal funds rate for such day Up to 3 months None General corporate purposes Aflac (1) uncommitted revolving 364 days November 30, 2020 $250 million $0 million USD three-month LIBOR plus 75 basis points per annum 3 months None General corporate purposes Aflac Incorporated (1) uncommitted revolving 364 days April 2, 2020 ¥50.0 billion ¥0.0 billion Three-month TIBOR plus 70 basis points per annum 3 months None General corporate purposes Aflac Incorporated (1) uncommitted revolving 364 days November 25, 2020 ¥50.0 billion ¥0.0 billion Three-month TIBOR plus 70 basis points per annum 3 months None General corporate purposes (1) Intercompany credit agreement

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
INCOME TAXES (Tables)	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The components of income tax expense (benefit) applicable to pretax earnings for the years ended December 31 were as follows: (In millions) Foreign U.S. Total 2019: Current $ 737 $ 69 $ 806 Deferred 183 152 335 Total income tax expense $ 920 $ 221 $ 1,141 2018: Current $ 771 $ 608 $ 1,379 Deferred 93 (409 ) (316 ) Total income tax expense $ 864 $ 199 $ 1,063 2017: Current $ 722 $ (91 ) $ 631 Deferred (24 ) (1,193 ) (1,217 ) Total income tax expense $ 698 $ (1,284 ) $ (586 )
Schedule of Effective Income Tax Rate Reconciliation	The principal reasons for the differences and the related tax effects for the years ended December 31 were as follows: (In millions) 2019 2018 2017 Income taxes based on U.S. statutory rates $ 933 $ 836 $ 1,406 Foreign rate differential 229 220 0 Write-down of U.S. deferred tax liabilities for tax reform change 0 0 (1,933 ) Utilization of foreign tax credit (6 ) (3 ) (27 ) Nondeductible expenses 10 21 10 Other, net (25 ) (11 ) (42 ) Income tax expense $ 1,141 $ 1,063 $ (586 )
Schedule of Income Tax Expense Benefit Intraperiod Tax Allocation	Total income tax expense for the years ended December 31 was allocated as follows: (In millions) 2019 2018 2017 Statements of earnings $ 1,141 $ 1,063 $ (586 ) Other comprehensive income (loss): Unrealized foreign currency translation gains (losses) during period 27 10 52 Unrealized gains (losses) on investment securities: Unrealized holding gains (losses) on investment 1,532 (787 ) 575 Reclassification adjustment for realized (gains) losses 5 (12 ) 1 Unrealized gains (losses) on derivatives during period (3 ) 0 0 Pension liability adjustment during period (18 ) (8 ) 3 Total income tax expense (benefit) related to items of 1,543 (797 ) 631 Total income taxes $ 2,684 $ 266 $ 45
Schedule of Deferred Tax Assets and Liabilities	The income tax effects of the temporary differences that gave rise to deferred income tax assets and liabilities as of December 31 were as follows: (In millions) 2019 2018 Deferred income tax liabilities: Deferred policy acquisition costs $ 3,492 $ 3,404 Unrealized gains and other basis differences on investments 4,485 1,307 Premiums receivable 152 149 Policy benefit reserves 3,442 3,828 Total deferred income tax liabilities 11,571 8,688 Deferred income tax assets: Unfunded retirement benefits 8 8 Other accrued expenses 36 40 Policy and contract claims 781 775 Foreign currency loss on Aflac Japan 16 38 Deferred compensation 162 163 Capital loss carryforwards 34 5 Depreciation 164 119 Anticipatory foreign tax credit 5,487 4,040 Deferred foreign tax credit 605 591 Other 204 150 Total deferred income tax assets before valuation allowance 7,497 5,929 Valuation allowance (1,340 ) (738 ) Total deferred income tax assets after valuation allowance 6,157 5,191 Net deferred income tax liability 5,414 3,497 Current income tax (asset) liability (44 ) 523 Total income tax liability $ 5,370 $ 4,020
Summary of Income Tax Contingencies	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows for the years ended December 31: (In millions) 2019 2018 Balance, beginning of year $ 15 $ 14 Additions for tax positions of prior years 2 1 Balance, end of year $ 17 $ 15

SHAREHOLDERS' EQUITY (Tables)

SHAREHOLDERS' EQUITY (Tables)	12 Months Ended
SHAREHOLDERS' EQUITY (Tables)	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Schedule of Common Stock Outstanding Roll Forward	The following table is a reconciliation of the number of shares of the Company's common stock for the years ended December 31. (In thousands of shares) 2019 2018 2017 Common stock - issued: Balance, beginning of period 1,347,540 1,345,762 1,342,498 Exercise of stock options and issuance of restricted shares 1,769 1,778 3,264 Balance, end of period 1,349,309 1,347,540 1,345,762 Treasury stock: Balance, beginning of period 592,254 564,852 530,877 Purchases of treasury stock: Share repurchase program 31,994 28,949 35,510 Other 592 392 1,018 Dispositions of treasury stock: Shares issued to AFL Stock Plan (1,610) (1,306) (1,782) Exercise of stock options (418) (519) (734) Other (296) (114) (37) Balance, end of period 622,516 592,254 564,852 Shares outstanding, end of period 726,793 755,286 780,910
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table presents the approximate number of share-based awards to purchase shares, on a weighted-average basis, that were considered to be anti-dilutive and were excluded from the calculation of diluted earnings per share at December 31: (In thousands) 2019 2018 2017 Anti-dilutive share-based awards 6 44 510
Schedule of Weighted Average Number of Shares	The weighted-average shares used in calculating earnings per share for the years ended December 31 were as follows: (In thousands of shares) 2019 2018 2017 Weighted-average outstanding shares used for calculating basic EPS 742,414 769,588 792,042 Dilutive effect of share-based awards 4,016 5,062 5,819 Weighted-average outstanding shares used for calculating diluted EPS 746,430 774,650 797,861
Changes in Accumulated Other Comprehensive Income (Loss)	The tables below are reconciliations of accumulated other comprehensive income by component for the years ended December 31. Changes in Accumulated Other Comprehensive Income 2019 (In millions) Unrealized Foreign Unrealized Unrealized Pension Total Balance, beginning of period $ (1,847 ) $ 4,234 $ (24 ) $ (212 ) $ 2,151 Other comprehensive 224 4,327 (9 ) (76 ) 4,466 Amounts reclassified from 0 (13 ) 0 11 (2 ) Net current-period other 224 4,314 (9 ) (65 ) 4,464 Balance, end of period $ (1,623 ) $ 8,548 $ (33 ) $ (277 ) $ 6,615 All amounts in the table above are net of tax. 2018 (In millions) Unrealized Foreign Unrealized Unrealized Pension Liability Adjustment Total Balance, beginning of period $ (1,750 ) $ 5,964 $ (23 ) $ (163 ) $ 4,028 Cumulative effect of change 0 (148 ) 0 0 (148 ) Cumulative effect of change (325 ) 734 (3 ) (32 ) 374 Other comprehensive 228 (2,350 ) 2 (30 ) (2,150 ) Amounts reclassified from 0 34 0 13 47 Net current-period other 228 (2,316 ) 2 (17 ) (2,103 ) Balance, end of period $ (1,847 ) $ 4,234 $ (24 ) $ (212 ) $ 2,151 All amounts in the table above are net of tax. 2017 (In millions) Unrealized Foreign Unrealized Unrealized Pension Liability Adjustment Total Balance, beginning of period $ (1,983 ) $ 4,805 $ (24 ) $ (168 ) $ 2,630 Other comprehensive 233 1,158 1 (6 ) 1,386 Amounts reclassified from 0 1 0 11 12 Net current-period other 233 1,159 1 5 1,398 Balance, end of period $ (1,750 ) $ 5,964 $ (23 ) $ (163 ) $ 4,028 All amounts in the table above are net of tax.
Reclassification out of Accumulated Other Comprehensive Income	The tables below summarize the amounts reclassified from each component of accumulated other comprehensive income based on source for the years ended December 31. Reclassifications Out of Accumulated Other Comprehensive Income (In millions) 2019 Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (13 ) Other-than-temporary impairment 31 Other gains (losses) 18 Total before tax (5 ) Tax (expense) or benefit (1) $ 13 Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (15 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 4 Tax (expense) or benefit (1) $ (11 ) Net of tax Total reclassifications for the period $ 2 Net of tax (1) Based on 26% blended tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 14 for additional details). (In millions) 2018 Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (63 ) Other-than-temporary impairment 17 Other gains (losses) (46 ) Total before tax 12 Tax (expense) or benefit (1) $ (34 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (18 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 5 Tax (expense) or benefit (1) $ (13 ) Net of tax Total reclassifications for the period $ (47 ) Net of tax (1) Based on 27% blended tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 14 for additional details). (In millions) 2017 Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (29 ) Other-than-temporary impairment 27 Other gains (losses) (2 ) Total before tax 1 Tax (expense) or benefit (1) $ (1 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (17 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 6 Tax (expense) or benefit (1) $ (11 ) Net of tax Total reclassifications for the period $ (12 ) Net of tax (1) Based on 35% tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 14 for additional details).

SHARE-BASED COMPENSATION (Table

SHARE-BASED COMPENSATION (Tables)	12 Months Ended
SHARE-BASED COMPENSATION (Tables)	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Schedule of Expense Recognized in Connection with Share Based Awards	The following table presents the impact of the expense recognized in connection with share-based awards for the periods ended December 31. (In millions, except for per-share amounts) 2019 2018 2017 Impact on earnings from continuing operations $ 59 $ 57 $ 51 Impact on earnings before income taxes 59 57 51 Impact on net earnings 46 45 35 Impact on net earnings per share: Basic $ .06 $ .06 $ .05 Diluted .06 .06 .05
Schedule of Share-based Compensation, Stock Options, Activity	The following table summarizes stock option activity under the employee stock option plan. (In thousands of shares) Stock Weighted-Average Outstanding at December 31, 2016 12,680 $ 26.28 Granted in 2017 626 35.80 Canceled in 2017 (236 ) 24.95 Exercised in 2017 (5,766 ) 30.11 Outstanding at December 31, 2017 7,304 28.03 Granted in 2018 67 44.59 Canceled in 2018 (167 ) 32.11 Exercised in 2018 (1,874 ) 26.78 Outstanding at December 31, 2018 5,330 28.54 Granted in 2019 0 0.00 Canceled in 2019 (40 ) 27.82 Exercised in 2019 (1,584 ) 25.97 Outstanding at December 31, 2019 3,706 $ 29.65
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable	(In thousands of shares) 2019 2018 2017 Shares exercisable, end of year 3,553 3,917 4,208
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The following table presents the assumptions used in valuing options granted during the years ended December 31. 2019 2018 2017 Expected term (years) 7.0 7.0 5.9 Expected volatility 18.0 % 22.0 % 26.0 % Annual forfeiture rate 3.9 3.6 3.4 Risk-free interest rate 2.9 2.5 2.5 Dividend yield 2.2 2.4 2.5
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range	The following table summarizes information about stock options outstanding and exercisable at December 31, 2019 . (In thousands of shares) Options Outstanding Options Exercisable Range of Stock Option Wgtd.-Avg. Wgtd.-Avg. Stock Option Wgtd.-Avg. $ 16.92 - $ 24.75 872 2.1 $ 23.58 872 $ 23.58 24.79 - 28.97 919 3.8 28.49 919 28.49 29.04 - 31.21 988 4.7 30.77 988 30.77 31.22 - 36.21 778 6.5 34.31 626 34.02 37.22 - 44.59 149 7.8 40.57 148 40.59 $ 16.92 - $ 44.59 3,706 4.4 $ 29.65 3,553 $ 29.40
Schedule of Cash Proceeds Received from Share-based Payment Awards	The following table summarizes stock option activity during the years ended December 31. (In millions) 2019 2018 2017 Total intrinsic value of options exercised $ 38 $ 34 $ 87 Cash received from options exercised 40 48 58 Tax benefit realized as a result of options exercised and 34 25 74
Schedule of Share-based Payment Award, Performance Based Restricted Stock, Valuation Assumptions	Key assumptions used to value PBRS granted during 2019 follows: (In millions) 2019 Expected volatility (based on Aflac Inc. and peer group historical daily stock price) 15.82 % Expected life from grant date (years) 2.9 Risk-free interest rate (based on U.S. Treasury yields at the date of grant) 2.51 %
Schedule of Nonvested Restricted Stock Units Activity	The value of restricted stock awards and restricted stock units is based on the fair market value of the Company's common stock at the date of grant. The following table summarizes restricted stock activity during the years ended December 31. (In thousands of shares) Shares Weighted-Average Restricted stock at December 31, 2016 3,736 $ 30.88 Granted in 2017 1,118 36.48 Canceled in 2017 (202 ) 32.23 Vested in 2017 (1,018 ) 31.09 Restricted stock at December 31, 2017 3,634 32.40 Granted in 2018 1,121 44.27 Canceled in 2018 (105 ) 34.39 Vested in 2018 (1,243 ) 31.64 Restricted stock at December 31, 2018 3,407 36.52 Granted in 2019 1,070 49.68 Canceled in 2019 (39 ) 41.60 Vested in 2019 (1,865 ) 32.73 Restricted stock at December 31, 2019 2,573 $ 44.66

STATUTORY ACCOUNTING AND DIVI_2

STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS (Tables)	12 Months Ended
STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS (Tables)	Dec. 31, 2019
Insurance [Abstract]
Profit Remittances Disclosure	Profits remitted by Aflac Japan to the Parent Company, after April 1, 2018, and to Aflac U.S., prior to April 1, 2018, were as follows for the years ended December 31: In Dollars In Yen (In millions of dollars and billions of yen) 2019 2018 2017 2019 2018 2017 Profit remittances $ 2,070 $ 808 $ 1,150 ¥ 225.2 ¥ 89.7 ¥ 129.3

BENEFIT PLANS (Tables)

BENEFIT PLANS (Tables)	12 Months Ended
BENEFIT PLANS (Tables)	Dec. 31, 2019
Schedule of Net Funded Status	Information with respect to the Company's benefit plans' assets and obligations as of December 31 was as follows: Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2019 2018 2019 2018 2019 2018 Projected benefit obligation: Benefit obligation, beginning of year $ 396 $ 341 $ 875 $ 908 $ 37 $ 36 Service cost 22 19 23 27 0 0 Interest cost 7 7 20 31 1 1 Actuarial (gain) loss 17 35 163 (3) (69 ) 4 4 Benefits and expenses paid (11 ) (11 ) (23 ) (22 ) (3 ) (4 ) Effect of foreign exchange 5 5 0 0 0 0 Benefit obligation, end of year 436 396 1,058 875 39 37 Plan assets: Fair value of plan assets, 289 270 465 448 0 0 Actual return on plan assets 24 (9 ) 98 (30 ) 0 0 Employer contributions 38 34 104 69 3 4 Benefits and expenses paid (11 ) (11 ) (23 ) (22 ) (3 ) (4 ) Effect of foreign exchange 4 5 0 0 0 0 Fair value of plan assets, 344 289 644 465 0 0 Funded status of the plans (1) $ (92 ) $ (107 ) $ (414 ) $ (410 ) $ (39 ) $ (37 ) Amounts recognized in accumulated other Net actuarial (gain) loss $ 92 $ 95 $ 259 $ 174 $ 12 $ 9 Prior service (credit) cost (2 ) (2 ) (4 ) (4 ) 0 0 Total included in accumulated $ 90 $ 93 $ 255 $ 170 $ 12 $ 9 Accumulated benefit obligation $ 390 $ 356 $ 886 $ 746 N/A (2) N/A (2) (1) Recognized in other liabilities in the consolidated balance sheets (2) Not applicable (3) Actuarial losses increased due to lower discount rates at the end of 2019. Also, additional funds were contributed to the U.S. funded defined benefit plan in 2019. The Company contributed $95 million in 2019 compared to $60 million in 2018.
Information for Pension Plans with Accumulated Benefit Obligation in Excess of Plan Assets	Information for Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets Pension Benefits Japan U.S. (In millions) 2019 2018 2019 2018 Accumulated benefit obligation $ 390 $ 356 $ 886 $ 746 Fair value of plan assets 344 289 644 465
Information for Pension Plans with a Projected Benefit Obligation in Excess of Plan Assets	Information for Pension Plans with a Projected Benefit Obligation in Excess of Plan Assets Pension Benefits Japan (1) U.S. (2) (In millions) 2019 2018 2019 2018 Projected benefit obligation $ 436 $ 396 $ 1,058 $ 875 Fair value of plan assets 344 289 644 465 (1) The net amount of projected benefit obligation and plan assets for the underfunded (including unfunded) Japan pension plan was $92 and $107 at December 31, 2019 and 2018, respectively, and was classified as liabilities on the statement of financial position. (2) The net amount of projected benefit obligation and plan assets for the underfunded (including unfunded) U.S. pension plan was $414 and $410 at December 31, 2019 and 2018, respectively, and was classified as liabilities on the statement of financial position.
Schedule of Assumptions Used	Pension Benefits Other Japan U.S. Postretirement Benefits 2019 2018 2017 2019 2018 2017 2019 2018 2017 Weighted-average actuarial assumptions: Discount rate - net periodic benefit cost 1.25 % 1.25 % 1.25 % 4.25 % 3.75 % 4.25 % 4.25 % 3.75 % 4.25 % Discount rate - benefit obligations .75 1.25 1.25 3.25 4.25 3.75 3.25 4.25 3.75 Expected long-term return on plan assets 2.00 2.00 2.00 6.25 6.50 6.75 N/A (1) N/A (1) N/A (1) Rate of compensation increase N/A (1) N/A (1) N/A (1) 4.00 4.00 4.00 N/A (1) N/A (1) N/A (1) Health care cost trend rates N/A (1) N/A (1) N/A (1) N/A (1) N/A N/A (1) 7.50 (2) 7.40 (2) 5.40 (2) (1) Not applicable (2) For the years 2019 , 2018 and 2017 , the health care cost trend rates are expected to trend down to 3.8% in 54 years , 4.1% in 61 years , and 4.5% in 77 years , respectively.
Schedule of Net Benefit Costs	Total net periodic benefit cost includes the following components: Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2019 2018 2017 2019 2018 2017 2019 2018 2017 Service cost $ 22 $ 19 $ 20 $ 23 $ 27 $ 24 $ 0 $ 0 $ 0 Interest cost 7 7 6 20 31 40 1 1 1 Expected return on plan (6 ) (6 ) (5 ) (29 ) (26 ) (24 ) 0 0 0 Amortization of net actuarial 4 1 2 10 16 14 1 1 1 Net periodic (benefit) cost $ 27 $ 21 $ 23 $ 24 $ 48 $ 54 $ 2 $ 2 $ 2
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	The following table summarizes the amounts recognized in other comprehensive loss (income) for the years ended December 31: Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2019 2018 2017 2019 2018 2017 2019 2018 2017 Net actuarial loss (gain) $ 1 $ 52 $ (21 ) $ 95 $ (13 ) $ 28 $ 4 $ 4 $ 0 Amortization of net actuarial loss (4 ) (1 ) (2 ) (10 ) (16 ) (14 ) (1 ) (1 ) (1 ) Total $ (3 ) $ 51 $ (23 ) $ 85 $ (29 ) $ 14 $ 3 $ 3 $ (1 )
Schedule of Expected Benefit Payments	The following table provides expected benefit payments, which reflect expected future service, as appropriate. Pension Benefits Other (In millions) Japan U.S. Postretirement Benefits 2020 $ 13 $ 25 $ 3 2021 12 27 4 2022 17 29 4 2023 14 30 4 2024 16 31 4 2025-2029 84 203 16
Schedule of Allocation of Plan Assets	Asset allocation targets as of December 31, 2019 were as follows: Japan Pension U.S. Pension Domestic equities 5 % 40 % International equities 20 20 Fixed income securities 66 40 Other 9 0 Total 100 % 100 %
Plan Assets
Fair Value, Assets Measured on Recurring Basis	The following table presents the fair value of Aflac Japan's pension plan assets that are measured at fair value on a recurring basis as of December 31. All of these assets are classified as Level 2 in the fair value hierarchy. (In millions) 2019 2018 Japan pension plan assets: Equities: Japanese equity securities $ 17 $ 14 International equity securities 67 50 Fixed income securities: Japanese bonds 20 34 International bonds 207 160 Insurance contracts 33 31 Total $ 344 $ 289 The following table presents the fair value of Aflac U.S.'s pension plan assets that are measured at fair value on a recurring basis as of December 31. All of these assets are classified as Level 1 in the fair value hierarchy. (In millions) 2019 2018 U.S. pension plan assets: Mutual funds: Large cap equity funds $ 179 $ 120 Mid cap equity funds 22 17 Real estate equity funds 16 13 International equity funds 112 92 Fixed income bond funds 209 179 Aflac Incorporated common stock 6 5 Cash and cash equivalents 100 39 Total $ 644 $ 465

Unaudited Consolidated Quarte_2

Unaudited Consolidated Quarterly Financial Data (Tables)	12 Months Ended
Unaudited Consolidated Quarterly Financial Data (Tables)	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	In management's opinion, the following quarterly financial information fairly presents the results of operations for such periods and is prepared on a basis consistent with the Company's annual audited financial statements. (In millions, except for per-share amounts) March 31, June 30, September 30, December 31, Net premium income $ 4,691 $ 4,681 $ 4,736 $ 4,671 Net investment income 878 878 936 886 Realized investment gains (losses) 71 (66 ) (153 ) 12 Other income (loss) 17 18 17 34 Total revenues 5,657 5,511 5,536 5,603 Total benefits and expenses 4,415 4,402 4,500 4,545 Earnings before income taxes 1,242 1,109 1,036 1,058 Total income tax 314 292 259 276 Net earnings $ 928 $ 817 $ 777 $ 782 Net earnings per basic share $ 1.23 $ 1.10 $ 1.05 $ 1.07 Net earnings per diluted share 1.23 1.09 1.04 1.06 Quarterly amounts may not agree in total to the corresponding annual amounts due to rounding. (In millions, except for per-share amounts) March 31, June 30, September 30, December 31, Net premium income $ 4,745 $ 4,706 $ 4,636 $ 4,591 Net investment income 837 862 870 874 Realized investment gains (losses) (134 ) 3 56 (355 ) Other income (loss) 16 18 15 16 Total revenues 5,464 5,589 5,577 5,126 Total benefits and expenses 4,482 4,458 4,431 4,404 Earnings before income taxes 982 1,131 1,146 722 Total income tax 265 299 301 197 Net earnings $ 717 $ 832 $ 845 $ 525 Net earnings per basic share $ .92 $ 1.08 $ 1.10 $ .69 Net earnings per diluted share .91 1.07 1.09 .69 Quarterly amounts may not agree in total to the corresponding annual amounts due to rounding.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Summary of Signficant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2020	Jan. 01, 2019	Jan. 01, 2018
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes			$ 0
Payments to Acquire Businesses, Gross	$ 75
Maximum
Significant Accounting Policies [Line Items]
Business Combination, Contingent Consideration, Liability	$ 21	$ 21
Aflac Japan
Significant Accounting Policies [Line Items]
Percentage of the Company's total revenues		69.00%	70.00%	70.00%
Percentage of the Company's total assets	83.00%	83.00%	84.00%
Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
New accounting pronouncement or change in accounting principle, cumulative effect of change on assets						$ 134
New accounting pronouncement or change in accounting principle, cumulative effect of change on liabilities						$ 134
Accounting Standards Update 2019-04 \| Forecast
Significant Accounting Policies [Line Items]
New accounting pronouncement or change in accounting principle effect of adoption reclassification from held to maturity to available for sale debt securities					$ 6,900
New accounting pronouncement or change in accounting principle effect of adoption unrealized gain loss net of tax reclassification to accumulated other comprehensive income					800
Accumulated other comprehensive income (loss)
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes			$ 226
Accumulated other comprehensive income (loss) \| Accounting Standards Update 2016-01
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes							$ (148)
Accumulated other comprehensive income (loss) \| Accounting Standards Update 2018-02
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes							374
Retained earnings
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes			$ (226)
Retained earnings \| Accounting Standards Update 2016-01
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes							148
Retained earnings \| Accounting Standards Update 2018-02
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes							$ (374)
Retained earnings \| Accounting Standards Update 2019-04 \| Forecast
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes					$ (56)

BUSINESS SEGMENT AND FOREIGN _3

BUSINESS SEGMENT AND FOREIGN INFORMATION - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Reportable insurance business segments \| segment	2
Total receivables related to Aflac Japan's operations	$ 828	$ 851
Aflac Japan
Segment Reporting Information [Line Items]
Total receivables related to Aflac Japan's operations	$ 258	$ 334
Percentage of total receivables related to Aflac Japan's operations	31.20%	39.20%
Maximum \| Machinery and equipment
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Maximum \| Building
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Useful Life	50 years
Maximum \| Furniture and fixtures
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Useful Life	20 years

BUSINESS SEGMENT AND FOREIGN _4

BUSINESS SEGMENT AND FOREIGN INFORMATION - Operations by Segment - Revenues (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance		$ 4,671	$ 4,736	$ 4,681	$ 4,691	$ 4,591	$ 4,636	$ 4,706	$ 4,745	$ 18,780	$ 18,677	$ 18,531
Net investment income		886	936	878	878	874	870	862	837	3,578	3,442	3,220
Total revenues		$ 5,603	$ 5,536	$ 5,511	$ 5,657	$ 5,126	$ 5,577	$ 5,589	$ 5,464	22,307	21,758	21,667
Total adjusted revenues										22,256	21,988	21,589
Realized investment gains (losses)	[1],[2],[3]									51	(230)	78
Life insurance
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										3,445	3,674	4,034
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										12,772	12,762	12,752
Net investment income, less amortized hedge costs	[1],[3]									2,496	2,403	2,235
Other income (loss)										45	41	41
Net investment income										2,753	2,639	2,463
Total revenues										15,313	15,206	15,028
Hedge costs										257	236	228
Net interest cash flows from derivatives										(17)
Aflac Japan \| Cancer
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										6,031	5,849	5,612
Aflac Japan \| Medical and other health
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										3,582	3,516	3,379
Aflac Japan \| Life insurance
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										3,159	3,397	3,761
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										5,808	5,708	5,563
Other income (loss)										22	8	5
Net investment income										720	727	721
Total revenues										6,550	6,443	6,289
Aflac U.S. \| Cancer
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										1,309	1,311	1,308
Aflac U.S. \| Life insurance
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										286	278	273
Aflac U.S. \| Accident and disability
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										2,665	2,611	2,537
Aflac U.S. \| Other health
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums, principally supplemental health insurance										1,548	1,508	1,445
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[2]									393	339	$ 272
Hedge income										$ 89	$ 36

[1]	Amortized hedge costs of $257 , $236 and $228 in 2019 , 2018 and 2017 , respectively, related to certain foreign currency exposure management strategies have been reclassified from realized investment gains (losses) and reported as a deduction from net investment income when analyzing operations.
[2]	Amortized hedge income of $89 in 2019 and $36 in 2018 related to certain foreign currency exposure management strategies has been reclassified from realized investment gains (losses) and reported as an increase to net investment income when analyzing operations.
[3]	Net interest cash flows from derivatives associated with certain investment strategies of $(17) in 2019 and an immaterial amount in 2018 have been reclassified from realized investment gains (losses) and included in adjusted earnings as a component of net investment income.

BUSINESS SEGMENT AND FOREIGN _5

BUSINESS SEGMENT AND FOREIGN INFORMATION - Operations by Segment - Pretax Earnings (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[1]									$ 4,461	$ 4,354	$ 4,087
Realized investment gains (losses)	[2],[3],[4],[5]									(15)	(297)	0
Other income (loss)	[6]									(1)	(74)	(69)
Earnings before income taxes		$ 1,058	$ 1,036	$ 1,109	$ 1,242	$ 722	$ 1,146	$ 1,131	$ 982	4,445	3,983	4,018
Income taxes applicable to pretax adjusted earnings										1,147	1,129	1,370
Effect of foreign currency translation on after tax adjusted earnings										15	28	(41)
Interest expense on debt										135	122	122
Aflac Japan
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[3],[5]									3,261	3,208	3,054
Hedge costs										257	236	228
Net interest cash flows from derivatives										(17)
Aflac U.S.
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings										1,272	1,285	1,245
Corporate and other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[2],[4]									(72)	(139)	(212)
Hedge income										89	36
Gain (loss) on change in fair value of derivative, interest rate component										$ 66	$ 67	77
5.50% subordinated notes due September 2052
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Expense on extinguishment of debt												$ 13

[1]	Includes $135 , $122 and $122 of interest expense on debt in 2019 , 2018 and 2017
[2]	A gain of $66 in 2019 , $67 in 2018 and $77 in 2017 , related to the interest rate component of the change in fair value of foreign currency swaps on notes payable have been reclassified from realized investment gains (losses) and included in adjusted earnings when analyzing operations.
[3]	Amortized hedge costs of $257 , $236 and $228 in 2019 , 2018 and 2017 , respectively, related to certain foreign currency exposure management strategies have been reclassified from realized investment gains (losses) and reported as a deduction from net investment income when analyzing operations.
[4]	Amortized hedge income of $89 in 2019 and $36 in 2018 related to certain foreign currency exposure management strategies has been reclassified from realized investment gains (losses) and reported as an increase to net investment income when analyzing operations.
[5]	Net interest cash flows from derivatives associated with certain investment strategies of $(17) in 2019 and an immaterial amount in 2018 have been reclassified from realized investment gains (losses) and included in adjusted earnings as a component of net investment income.
[6]	Includes expense of $13 in 2017 for the early extinguishment of debt

BUSINESS SEGMENT AND FOREIGN _6

BUSINESS SEGMENT AND FOREIGN INFORMATION - Operations by Segment - Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 152,768	$ 140,406
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	127,523	118,342
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	20,945	19,100
Corporate and other
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 4,300	$ 2,964

BUSINESS SEGMENT AND FOREIGN _7

BUSINESS SEGMENT AND FOREIGN INFORMATION - Yen/Dollar Exchange Rates Used (Detail) $ in Millions		12 Months Ended
		Dec. 31, 2019USD ($)¥ / $	Dec. 31, 2018USD ($)¥ / $	Dec. 31, 2017USD ($)¥ / $
Segment Reporting, Other Significant Reconciling Item [Line Items]
Weighted-average yen/dollar exchange rate \| ¥ / $	[1]	109.07	110.39	112.16
Yen percent strengthening (weakening)		1.20%	1.60%	(3.10%)
Exchange effect on pretax operating earnings (in millions)		$ 20	$ 38	$ (63)
Yen/dollar exchange rate at December 31 \| ¥ / $	[1]	109.56	111
Yen percent strengthening (weakening)		1.30%	1.80%
Exchange effect on total assets
Segment Reporting, Other Significant Reconciling Item [Line Items]
Exchange effect		$ 1,225	$ 1,362
Exchange effect on total liabilities
Segment Reporting, Other Significant Reconciling Item [Line Items]
Exchange effect		$ 1,533	$ 1,270

[1]	Rates are based on the published MUFG Bank, Ltd. telegraphic transfer middle rate (TTM)

BUSINESS SEGMENT AND FOREIGN _8

BUSINESS SEGMENT AND FOREIGN INFORMATION - Information on Transfers of Funds from Aflac Japan (Detail) $ in Millions, ¥ in Billions	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2019JPY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2018JPY (¥)	Dec. 31, 2017USD ($)	Dec. 31, 2017JPY (¥)
Segment Reporting [Abstract]
Management fees	$ 75		$ 136		$ 93
Allocated expenses	4		24		109
Profit remittances	2,070	¥ 225.2	808	¥ 89.7	1,150	¥ 129.3
Total transfers from Aflac Japan	$ 2,149		$ 968		$ 1,352

BUSINESS SEGMENT AND FOREIGN _9

BUSINESS SEGMENT AND FOREIGN INFORMATION - Classes of Property and Equipment (Detail) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Property and equipment:
Land		$ 168	$ 168
Buildings		473	456
Equipment		549	400
Total property and equipment		1,190	1,024
Less accumulated depreciation		609	581
Net property and equipment	[1]	$ 581	$ 443

[1]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2019 related to leases.

INVESTMENTS - Components of Net

INVESTMENTS - Components of Net Investment Income (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									$ 3,755	$ 3,590	$ 3,334
Less investment expenses									177	148	114
Net investment income	$ 886	$ 936	$ 878	$ 878	$ 874	$ 870	$ 862	$ 837	3,578	3,442	3,220
Fixed maturity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									3,141	3,142	3,173
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									37	38	42
Commercial mortgage and other loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									468	333	86
Other investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									53	36	8
Short-term investments and cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									$ 56	$ 41	$ 25

INVESTMENTS - Available-for-Sal

INVESTMENTS - Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	$ 79,371	$ 76,856
Gross Unrealized Gains	12,266	7,733
Gross Unrealized Losses	375	1,694
Fair Value	91,262	82,895
Yen-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	45,684	44,027
Gross Unrealized Gains	7,410	5,308
Gross Unrealized Losses	113	435
Fair Value	52,981	48,900
Dollar-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	33,687	32,829
Gross Unrealized Gains	4,856	2,425
Gross Unrealized Losses	262	1,259
Fair Value	38,281	33,995
Japan government and agencies \| Yen-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	30,929	30,637
Gross Unrealized Gains	5,169	3,700
Gross Unrealized Losses	0	140
Fair Value	36,098	34,197
U.S. government and agencies \| Dollar-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	293	137
Gross Unrealized Gains	9	9
Gross Unrealized Losses	0	1
Fair Value	302	145
Municipalities
Debt Securities, Available-for-Sale [Line Items]
Fair Value	1,847	1,863
Municipalities \| Yen-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	516	385
Gross Unrealized Gains	116	32
Gross Unrealized Losses	3	9
Fair Value	629	408
Municipalities \| Dollar-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	1,077	1,343
Gross Unrealized Gains	141	120
Gross Unrealized Losses	0	8
Fair Value	1,218	1,455
Mortgage- and asset-backed securities
Debt Securities, Available-for-Sale [Line Items]
Fair Value	410	339
Mortgage- and asset-backed securities \| Yen-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	229	155
Gross Unrealized Gains	25	22
Gross Unrealized Losses	0	0
Fair Value	254	177
Mortgage- and asset-backed securities \| Dollar-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	149	155
Gross Unrealized Gains	7	8
Gross Unrealized Losses	0	1
Fair Value	156	162
Public utilities
Debt Securities, Available-for-Sale [Line Items]
Fair Value	6,780	7,171
Public utilities \| Yen-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	1,855	1,732
Gross Unrealized Gains	406	280
Gross Unrealized Losses	0	4
Fair Value	2,261	2,008
Public utilities \| Dollar-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	3,804	4,772
Gross Unrealized Gains	725	496
Gross Unrealized Losses	10	105
Fair Value	4,519	5,163
Sovereign and supranational
Debt Securities, Available-for-Sale [Line Items]
Fair Value	1,042	1,260
Sovereign and supranational \| Yen-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	680	826
Gross Unrealized Gains	50	123
Gross Unrealized Losses	0	0
Fair Value	730	949
Sovereign and supranational \| Dollar-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	239	251
Gross Unrealized Gains	73	60
Gross Unrealized Losses	0	0
Fair Value	312	311
Banks/financial institutions
Debt Securities, Available-for-Sale [Line Items]
Fair Value	10,287	8,918
Banks/financial institutions \| Yen-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	6,152	5,440
Gross Unrealized Gains	700	502
Gross Unrealized Losses	86	238
Fair Value	6,766	5,704
Banks/financial institutions \| Dollar-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	2,879	2,860
Gross Unrealized Gains	646	389
Gross Unrealized Losses	4	35
Fair Value	3,521	3,214
Other corporate
Debt Securities, Available-for-Sale [Line Items]
Fair Value	34,496	29,002
Other corporate \| Yen-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	5,323	4,852
Gross Unrealized Gains	944	649
Gross Unrealized Losses	24	44
Fair Value	6,243	5,457
Other corporate \| Dollar-denominated
Debt Securities, Available-for-Sale [Line Items]
Cost or Amortized Cost	25,246	23,311
Gross Unrealized Gains	3,255	1,343
Gross Unrealized Losses	248	1,109
Fair Value	$ 28,253	$ 23,545

INVESTMENTS - Held-to-Maturity

INVESTMENTS - Held-to-Maturity Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	$ 30,085	$ 30,318
Gross Unrealized Gains	7,519	6,470
Gross Unrealized Losses	10	66
Fair Value	37,594	36,722
Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	30,085	30,318
Gross Unrealized Gains	7,519	6,470
Gross Unrealized Losses	10	66
Fair Value	37,594	36,722
Japan government and agencies \| Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	22,241	21,712
Gross Unrealized Gains	6,050	5,326
Gross Unrealized Losses	0	0
Fair Value	28,291	27,038
Municipalities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	821	359
Fair Value	1,083	469
Municipalities \| Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	821	359
Gross Unrealized Gains	262	110
Gross Unrealized Losses	0	0
Fair Value	1,083	469
Mortgage- and asset-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	16	14
Fair Value	17	15
Mortgage- and asset-backed securities \| Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	16	14
Gross Unrealized Gains	1	1
Gross Unrealized Losses	0	0
Fair Value	17	15
Public utilities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	2,535	2,727
Fair Value	2,954	2,973
Public utilities \| Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	2,535	2,727
Gross Unrealized Gains	419	254
Gross Unrealized Losses	0	8
Fair Value	2,954	2,973
Sovereign and supranational
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	1,123	1,551
Fair Value	1,320	1,840
Sovereign and supranational \| Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	1,123	1,551
Gross Unrealized Gains	197	289
Gross Unrealized Losses	0	0
Fair Value	1,320	1,840
Banks/financial institutions
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	916	1,445
Fair Value	1,018	1,583
Banks/financial institutions \| Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	916	1,445
Gross Unrealized Gains	105	158
Gross Unrealized Losses	3	20
Fair Value	1,018	1,583
Other corporate
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	2,433	2,510
Fair Value	2,911	2,804
Other corporate \| Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	2,433	2,510
Gross Unrealized Gains	485	332
Gross Unrealized Losses	7	38
Fair Value	$ 2,911	$ 2,804

INVESTMENTS - Equity Securities

INVESTMENTS - Equity Securities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Equity Securities, FV-NI [Line Items]
Fair Value	$ 802	$ 987
Yen-denominated
Equity Securities, FV-NI [Line Items]
Fair Value	658	641
Dollar-denominated
Equity Securities, FV-NI [Line Items]
Fair Value	$ 144	$ 346

INVESTMENTS - Contractual and E

INVESTMENTS - Contractual and Economic Maturities of Investments in Fixed Maturities (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Available for sale:
Due in one year or less	$ 583
Due after one year through five years	7,933
Due after five years through 10 years	11,347
Due after 10 years	59,130
Mortgage- and asset-backed securities	378
Total fixed maturity securities, available for sale, amortized cost	79,371	$ 76,856
Held to maturity:
Due in one year or less	265
Due after one year through five years	1,227
Due after five years through 10 years	532
Due after 10 years	28,045
Mortgage- and asset-backed securities	16
Total fixed maturity securities, held to maturity, amortized cost	30,085	30,318
Available for sale:
Due in one year or less	612
Due after one year through five years	8,122
Due after five years through 10 years	12,819
Due after 10 years	69,299
Mortgage- and asset-backed securities	410
Total fixed maturity securities, available for sale, fair value	91,262	82,895
Held to maturity:
Due in one year or less	270
Due after one year through five years	1,330
Due after five years through 10 years	599
Due after 10 years	35,378
Mortgage- and asset-backed securities	17
Total fixed maturity securities, held to maturity, fair value	$ 37,594	$ 36,722

INVESTMENTS - Investment Exposu

INVESTMENTS - Investment Exposures Individually Exceeded 10% of Shareholders' Equity (Detail) - Japan National Government - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Summary of Investment Holdings [Line Items]
Credit Rating	[1]	A+	A+
Amortized Cost	[1]	$ 51,726	$ 51,207
Fair Value	[1]	$ 62,584	$ 59,945

[1]	Japan Government Bonds (JGBs) or JGB-backed securities

INVESTMENTS - Information Regar

INVESTMENTS - Information Regarding Pretax Realized Gains and Losses From Investments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gain (Loss) on Securities [Line Items]
Loan loss reserves	$ (18)	$ (19)	$ (8)
Derivative gains (losses)	(174)	(224)	(109)
Foreign currency gains (losses)	(62)	(10)	(33)
Total realized investment gains (losses)	(135)	(430)	(151)
Loan receivables
Gain (Loss) on Securities [Line Items]
Total realized investment gains (losses)	(18)	(19)	(8)
Derivatives and other
Gain (Loss) on Securities [Line Items]
Total realized investment gains (losses)	(236)	(234)	(142)
Equity securities
Gain (Loss) on Securities [Line Items]
Total realized investment gains (losses)	101	(131)	71	[1]
Other-than-temporary impairment losses realized			(22)
Available-for-sale securities \| Fixed maturity securities
Gain (Loss) on Securities [Line Items]
Gross gains from sales	115	101	51
Gross losses from sales	(68)	(156)	(68)
Foreign currency gains (losses) on sales and redemptions	(16)	73	(48)
Other-than-temporary impairment losses realized	(13)	(64)	(7)
Total realized investment gains (losses)	$ 18	$ (46)	$ (72)

[1]	Includes impairments of $22 in 2017

INVESTMENTS - Information Reg_2

INVESTMENTS - Information Regarding Changes in Unrealized Gains and Losses from Investments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in unrealized gains (losses):
Changes in unrealized gains (losses)	$ 5,852	$ (3,142)	$ 1,728
Fixed maturity securities \| Available-for-sale securities
Changes in unrealized gains (losses):
Changes in unrealized gains (losses)	5,852	(3,142)	1,657
Equity securities
Changes in unrealized gains (losses):
Changes in unrealized gains (losses)	$ 0	$ 0	$ 71

INVESTMENTS - Net Effect on Sha

INVESTMENTS - Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investments [Abstract]
Unrealized gains (losses) on securities available for sale	$ 11,891	$ 6,039
Deferred income taxes	(3,343)	(1,805)
Shareholders' equity, unrealized gains (losses) on investment securities	$ 8,548	$ 4,234

INVESTMENTS - Fair Value and Gr

INVESTMENTS - Fair Value and Gross Unrealized Losses for Securities That Have Been in Continuous Unrealized Loss Position (Detail) - Fixed maturity securities - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	$ 7,190	$ 24,484
Total Unrealized Losses	385	1,760
Less Than 12 months Fair Value	3,423	16,389
Less Than 12 months Unrealized Losses	178	985
12 months or longer Fair Value	3,767	8,095
12 months or longer Unrealized Losses	207	775
Yen-denominated \| Japan government and agencies
Investments, Unrealized Loss Position [Line Items]
Total Fair Value		3,604
Total Unrealized Losses		140
Less Than 12 months Fair Value		3,604
Less Than 12 months Unrealized Losses		140
12 months or longer Fair Value		0
12 months or longer Unrealized Losses		0
Yen-denominated \| Municipalities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	80	148
Total Unrealized Losses	3	9
Less Than 12 months Fair Value	80	148
Less Than 12 months Unrealized Losses	3	9
12 months or longer Fair Value	0	0
12 months or longer Unrealized Losses	0	0
Yen-denominated \| Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value		604
Total Unrealized Losses		12
Less Than 12 months Fair Value		604
Less Than 12 months Unrealized Losses		12
12 months or longer Fair Value		0
12 months or longer Unrealized Losses		0
Yen-denominated \| Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,828	3,057
Total Unrealized Losses	89	258
Less Than 12 months Fair Value	1,828	3,057
Less Than 12 months Unrealized Losses	89	258
12 months or longer Fair Value	0	0
12 months or longer Unrealized Losses	0	0
Yen-denominated \| Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	636	1,306
Total Unrealized Losses	31	82
Less Than 12 months Fair Value	636	1,306
Less Than 12 months Unrealized Losses	31	82
12 months or longer Fair Value	0	0
12 months or longer Unrealized Losses	0	0
Dollar-denominated \| U.S. government and agencies
Investments, Unrealized Loss Position [Line Items]
Total Fair Value		67
Total Unrealized Losses		1
Less Than 12 months Fair Value		67
Less Than 12 months Unrealized Losses		1
12 months or longer Fair Value		0
12 months or longer Unrealized Losses		0
Dollar-denominated \| Municipalities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value		515
Total Unrealized Losses		8
Less Than 12 months Fair Value		515
Less Than 12 months Unrealized Losses		8
12 months or longer Fair Value		0
12 months or longer Unrealized Losses		0
Dollar-denominated \| Mortgage- and asset-backed securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value		74
Total Unrealized Losses		1
Less Than 12 months Fair Value		74
Less Than 12 months Unrealized Losses		1
12 months or longer Fair Value		0
12 months or longer Unrealized Losses		0
Dollar-denominated \| Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	306	1,585
Total Unrealized Losses	10	105
Less Than 12 months Fair Value	69	892
Less Than 12 months Unrealized Losses	2	48
12 months or longer Fair Value	237	693
12 months or longer Unrealized Losses	8	57
Dollar-denominated \| Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	79	625
Total Unrealized Losses	4	35
Less Than 12 months Fair Value	18	340
Less Than 12 months Unrealized Losses	0	19
12 months or longer Fair Value	61	285
12 months or longer Unrealized Losses	4	16
Dollar-denominated \| Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	4,261	12,899
Total Unrealized Losses	248	1,109
Less Than 12 months Fair Value	792	5,782
Less Than 12 months Unrealized Losses	53	407
12 months or longer Fair Value	3,469	7,117
12 months or longer Unrealized Losses	$ 195	$ 702

INVESTMENTS - Commercial Mortga

INVESTMENTS - Commercial Mortgage and Other Loans by Property Type (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 9,614	$ 6,946
Percent of total commercial mortgage and other loans	100.00%	100.00%
Valuation allowance	$ (45)	$ (27)
Total net commercial mortgage and other loans	9,569	6,919
Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 5,472	$ 4,394
Percent of total commercial mortgage and other loans	57.00%	63.20%
Valuation allowance	$ (22)	$ (17)
Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 1,710	$ 1,065
Percent of total commercial mortgage and other loans	17.70%	15.40%
Valuation allowance	$ (3)	$ (1)
Middle market loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 2,432	$ 1,487
Percent of total commercial mortgage and other loans	25.30%	21.40%
Valuation allowance	$ (20)	$ (9)
Office \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 1,800	$ 1,621
Percent of total commercial mortgage and other loans	18.70%	23.30%
Office \| Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 410	$ 281
Percent of total commercial mortgage and other loans	4.30%	4.10%
Retail \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 131	$ 147
Percent of total commercial mortgage and other loans	1.40%	2.10%
Retail \| Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 348	$ 316
Percent of total commercial mortgage and other loans	3.50%	4.60%
Apartments/Multi-Family \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 2,085	$ 1,706
Percent of total commercial mortgage and other loans	21.70%	24.60%
Apartments/Multi-Family \| Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 569	$ 369
Percent of total commercial mortgage and other loans	5.90%	5.30%
Industrial \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 256	$ 250
Percent of total commercial mortgage and other loans	2.70%	3.60%
Industrial \| Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 383	$ 99
Percent of total commercial mortgage and other loans	4.00%	1.40%
Hospitality \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 1,036	$ 531
Percent of total commercial mortgage and other loans	10.80%	7.60%
Other \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 164	$ 139
Percent of total commercial mortgage and other loans	1.70%	2.00%

INVESTMENTS - Allowance for Loa

INVESTMENTS - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	$ (27)
Addition to (release of) allowance for credit losses	(18)	$ (19)	$ (8)
Balance, end of period	(45)	(27)
Commercial mortgage loans
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	(1)
Addition to (release of) allowance for credit losses	(2)
Balance, end of period	(3)	(1)
Transitional real estate loans
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	(17)
Addition to (release of) allowance for credit losses	(5)
Balance, end of period	(22)	(17)
Middle market loans
Allowance for Loan Losses by Portfolio Segment [Roll Forward]
Balance, beginning of period	(9)
Addition to (release of) allowance for credit losses	(11)
Balance, end of period	$ (20)	$ (9)

INVESTMENTS - Commercial Mort_2

INVESTMENTS - Commercial Mortgage Loans and Transitional Real Estate Loans by Key Credit Quality Indicators (Details) $ in Millions	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	$ 9,614	$ 6,946
Weighted average debt-service coverage ratio	2.38	2.45
Transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	$ 5,472	$ 4,394
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	1,710	1,065
Commercial mortgage and transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	7,182	5,459
Loan to Value Ratio, Zero to Fifty-nine Point Nine-nine Percent \| Transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	1,424	819
Loan to Value Ratio, Zero to Fifty-nine Point Nine-nine Percent \| Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	1,390	877
Loan to Value Ratio, Zero to Fifty-nine Point Nine-nine Percent \| Commercial mortgage and transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	2,814	1,696
Loan to Value Ratio, Sixty to Sixty-nine Point Nine-nine Percent \| Transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	1,927	1,681
Loan to Value Ratio, Sixty to Sixty-nine Point Nine-nine Percent \| Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	297	165
Loan to Value Ratio, Sixty to Sixty-nine Point Nine-nine Percent \| Commercial mortgage and transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	2,224	1,846
Loan to Value Ratio, Seventy to Seventy-nine Point Nine-nine Percent \| Transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	2,085	1,558
Loan to Value Ratio, Seventy to Seventy-nine Point Nine-nine Percent \| Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	23	23
Loan to Value Ratio, Seventy to Seventy-nine Point Nine-nine Percent \| Commercial mortgage and transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	2,108	1,581
Loan to Value Ratio Eighty Percent and Above \| Transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	36	336
Loan to Value Ratio Eighty Percent and Above \| Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	0	0
Loan to Value Ratio Eighty Percent and Above \| Commercial mortgage and transitional real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Commercial mortgage and other loans, gross	$ 36	$ 336

INVESTMENTS - Other Investments

INVESTMENTS - Other Investments (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Other investments		$ 1,477	$ 787
Policy loans
Investment [Line Items]
Other investments		250	232
Short-term investments
Investment [Line Items]
Other investments	[1]	628	152
Limited partnerships
Investment [Line Items]
Other investments		569	377
Other Investments
Investment [Line Items]
Other investments		$ 30	$ 26

[1]	Includes securities lending collateral

INVESTMENTS - Investments in Co

INVESTMENTS - Investments in Consolidated Variable Interest Entities (Detail) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Available for sale, fixed maturity securities, amortized cost		$ 79,371	$ 76,856
Available for sale, fixed maturity securities		91,262	82,895
Equity securities		802	987
Commercial mortgage and other loans		9,569	6,919
Commercial mortgage and other loans, fair value		9,648	6,893
Other investments		1,477	787
Asset derivatives		482	417
Assets, fair value		98,070	88,788
Liability derivatives		586	387
Liabilities		123,809	116,944
Liabilities, fair value		586	387
Variable Interest Entity, Consolidated
Variable Interest Entity [Line Items]
Available for sale, fixed maturity securities, amortized cost		3,308	3,849
Available for sale, fixed maturity securities		4,312	4,466
Equity securities, FV-NI, cost		0	160
Equity securities		0	160
Commercial mortgage and other loans		7,956	5,528
Commercial mortgage and other loans, fair value		8,015	5,506
Other investments	[1]	494	328
Other investments, fair value	[1]	494	328
Asset derivatives, amortized cost	[2]	169	182
Asset derivatives	[2]	169	182
Assets, amortized cost		11,927	10,047
Assets, fair value		12,990	10,642
Liability derivatives, amortized cost	[2]	126	102
Liability derivatives	[2]	126	102
Liabilities		126	102
Liabilities, fair value		$ 126	$ 102

[1]	Consists entirely of alternative investments in limited partnerships
[2]	Consists entirely of derivatives

INVESTMENTS - Investments in Va

INVESTMENTS - Investments in Variable Interest Entities Not Consolidated (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Available for sale, fixed maturity securities, amortized cost		$ 79,371	$ 76,856
Available for sale, fixed maturity securities		91,262	82,895
Securities held to maturity, fixed maturities, amortized cost		30,085	30,318
Held to maturity, fixed maturity securities, fair value		37,594	36,722
Other investments		1,477	787
Assets, fair value		98,070	88,788
Variable Interest Entity, Not Consolidated
Variable Interest Entity [Line Items]
Available for sale, fixed maturity securities, amortized cost		4,129	4,575
Available for sale, fixed maturity securities		4,884	4,982
Securities held to maturity, fixed maturities, amortized cost		1,848	2,007
Held to maturity, fixed maturity securities, fair value		2,236	2,254
Other investments	[1]	75	49
Other investments, fair value	[1]	74	49
Assets, amortized cost		6,052	6,631
Assets, fair value		$ 7,194	$ 7,285

[1]	Consists entirely of alternative investments in limited partnerships

INVESTMENTS - Securities Lendin

INVESTMENTS - Securities Lending Transactions Accounted for as Secured Borrowings (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		$ 6,635	$ 2,242
Gross amount of recognized liabilities for securities lending		1,876	1,052
Amounts related to agreements not included in offsetting disclosure in Note 4		4,759	1,190
Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		5,772	1,577
Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		35	27
Municipalities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred			5
Sovereign and supranational
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		2
Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		48	74
Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		778	549
Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	10
Maturity Overnight and Continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	863	665
Maturity Overnight and Continuous \| Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	0	0
Maturity Overnight and Continuous \| Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	35	27
Maturity Overnight and Continuous \| Municipalities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]		5
Maturity Overnight and Continuous \| Sovereign and supranational
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	2
Maturity Overnight and Continuous \| Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	48	74
Maturity Overnight and Continuous \| Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	778	549
Maturity Overnight and Continuous \| Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	0	10
Maturity up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		1,013	387
Maturity up to 30 Days \| Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		1,013	387
Maturity up to 30 Days \| Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days \| Municipalities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred			0
Maturity up to 30 Days \| Sovereign and supranational
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0
Maturity up to 30 Days \| Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days \| Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days \| Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity Greater than 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		4,759	1,190
Maturity Greater than 90 Days \| Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		4,759	1,190
Maturity Greater than 90 Days \| Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity Greater than 90 Days \| Municipalities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred			0
Maturity Greater than 90 Days \| Sovereign and supranational
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0
Maturity Greater than 90 Days \| Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity Greater than 90 Days \| Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity Greater than 90 Days \| Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		$ 0	$ 0

[1]	The related loaned security, under the Company's Aflac U.S. securities lending program, can be returned to the Company at the transferee's discretion; therefore, they are classified as Overnight and Continuous.

INVESTMENTS - Additional Inform

INVESTMENTS - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)investment	Dec. 31, 2018USD ($)investment	Dec. 31, 2017USD ($)investment
Schedule of Investments [Line Items]
Reclassified investments from the held-to-maturity portfolio to the available-for-sale portfolio, number of investments \| investment	0	0	3
Reclassified investments from the held-to-maturity portfolio to the available-for-sale portfolio, amortized cost			$ 773
Reclassified investments from the held-to-maturity portfolio to the available-for-sale portfolio, aggregate unrealized gain (loss)			$ 47
Equity securities, FV-NI, unrealized gain (loss)	$ 64
Transitional real estate loan commitments	875
Commercial mortgage loan commitments	27
Middle market loan program unfunded amount	99	$ 56
Middle market loan commitments	502
Specific loan loss reserves	$ 6	$ 0
Number of loan loss reserves related to specific middle market loans	2
Limited partnerships investment commitments	$ 1,300
Percentage that the lending policy requires that the fair value of the securities and/or unrestricted cash received as collateral be of the fair value of the loaned securities	102.00%
Percentage that the lending policy requires that the fair value of the unrestricted cash received as collateral be of the fair value of the loaned securities	100.00%
Fair value of debt securities on deposit with regulatory authorities in the United States and Japan	$ 18
Commercial mortgage and transitional real estate loans \| California
Schedule of Investments [Line Items]
Concentration Risk, Percentage	20.00%
Commercial mortgage and transitional real estate loans \| Texas
Schedule of Investments [Line Items]
Concentration Risk, Percentage	15.00%
Commercial mortgage and transitional real estate loans \| Florida
Schedule of Investments [Line Items]
Concentration Risk, Percentage	10.00%

DERIVATIVE INSTRUMENTS - Additi

DERIVATIVE INSTRUMENTS - Additional Information (Detail) $ in Millions	Dec. 31, 2019USD ($)yr	Dec. 31, 2018USD ($)	Mar. 31, 2015USD ($)	Nov. 30, 2014USD ($)	Jun. 30, 2013USD ($)	Feb. 29, 2012USD ($)
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Cash flow hedging activity, maximum time period l yr \| yr	7
Derivative, net liability position, aggregate fair value	$ 301	$ 139
Additional collateral, aggregate fair value	46
4.00% senior notes due February 2022
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	350					$ 350
3.625% senior notes due June 2023
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	700				$ 700
3.625% senior notes due November 2024
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	750			$ 750
3.25% senior notes due March 2025
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	$ 450		$ 450

DERIVATIVE INSTRUMENTS - Summar

DERIVATIVE INSTRUMENTS - Summary of Balance Sheet Classification of Derivative Fair Value Amounts, as well as Gross Asset and Liability Fair Value Amounts (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	$ 61,695	$ 38,355
Derivative asset, fair value, gross asset including not subject to master netting arrangement	482	417
Derivative liability, fair value, gross liability including not subject to master netting arrangement	586	387
Asset derivatives fair value	313	234
Liability derivatives fair value	460	285
Cash flow hedges
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	75	75
Asset derivatives fair value	0	1
Liability derivatives fair value	8	4
Cash flow hedges \| Foreign currency swaps \| Variable Interest Entity
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	75	75
Asset derivatives fair value	0	1
Liability derivatives fair value	8	4
Fair value hedges
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	12,780	11,656
Asset derivatives fair value	0	3
Liability derivatives fair value	43	36
Fair value hedges \| Foreign currency forwards
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	964	2,086
Asset derivatives fair value	0	0
Liability derivatives fair value	38	34
Fair value hedges \| Foreign currency options
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	11,573	9,070
Asset derivatives fair value	0	3
Liability derivatives fair value	5	1
Fair value hedges \| Interest rate swaptions
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	243	500
Asset derivatives fair value	0	0
Liability derivatives fair value	0	1
Net investment hedge
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	6,952	0
Asset derivatives fair value	72	0
Liability derivatives fair value	2	0
Net investment hedge \| Foreign currency forwards
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	4,952	0
Asset derivatives fair value	72	0
Liability derivatives fair value	2	0
Net investment hedge \| Foreign currency options
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	2,000	0
Asset derivatives fair value	0	0
Liability derivatives fair value	0	0
Non-qualifying strategies
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	41,888	26,624
Asset derivatives fair value	410	413
Liability derivatives fair value	533	347
Non-qualifying strategies \| Foreign currency swaps \| Variable Interest Entity
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	2,587	2,587
Asset derivatives fair value	169	181
Liability derivatives fair value	118	101
Non-qualifying strategies \| Foreign currency swaps \| Consolidated Entity Excluding Variable Interest Entities (VIE)
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	2,800	2,800
Asset derivatives fair value	72	103
Liability derivatives fair value	78	129
Non-qualifying strategies \| Foreign currency forwards
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	19,821	16,057
Asset derivatives fair value	166	126
Liability derivatives fair value	337	117
Non-qualifying strategies \| Foreign currency options
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	9,553	430
Asset derivatives fair value	0	0
Liability derivatives fair value	0	0
Non-qualifying strategies \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	7,120	4,750
Asset derivatives fair value	3	3
Liability derivatives fair value	0	0
Non-qualifying strategies \| Interest rate swaptions
Derivatives, Fair Value [Line Items]
Net derivatives notional amount	7	0
Asset derivatives fair value	0	0
Liability derivatives fair value	$ 0	$ 0

DERIVATIVE INSTRUMENTS - Gains

DERIVATIVE INSTRUMENTS - Gains (Losses) Recognized on Fair Value Hedging Relationships (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized for derivatives		$ (66)	$ 129	$ 119
Gains (losses) on derivatives excluded from effectiveness testing	[1]	(80)	(101)	(192)
Gain (losses) on derivatives included in effectiveness testing	[2]	14	230	311
Gains (losses) recognized for hedged items	[2]	(12)	(242)	(288)
Net realized gains (losses) recognized for fair value hedge		2	(12)	23
Fixed maturity securities \| Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized for derivatives		(50)	126
Gains (losses) on derivatives excluded from effectiveness testing	[1]	(64)	(104)
Gain (losses) on derivatives included in effectiveness testing	[2]	14	230
Gains (losses) recognized for hedged items	[2]	(12)	(242)
Net realized gains (losses) recognized for fair value hedge		2	(12)
Fixed maturity securities \| Foreign currency options
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized for derivatives		(7)	4	21
Gains (losses) on derivatives excluded from effectiveness testing	[1]	(7)	4	10
Gain (losses) on derivatives included in effectiveness testing	[2]	0	0	11
Gains (losses) recognized for hedged items	[2]	0	0	(10)
Net realized gains (losses) recognized for fair value hedge		0	0	1
Fixed maturity securities \| Interest rate swaptions
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized for derivatives		(9)	(1)
Gains (losses) on derivatives excluded from effectiveness testing	[1]	(9)	(1)
Gain (losses) on derivatives included in effectiveness testing	[2]	0	0
Gains (losses) recognized for hedged items	[2]	0	0
Net realized gains (losses) recognized for fair value hedge		$ 0	$ 0
Fixed maturity and equity securities \| Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized for derivatives				98
Gains (losses) on derivatives excluded from effectiveness testing	[1]			(202)
Gain (losses) on derivatives included in effectiveness testing	[2]			300
Gains (losses) recognized for hedged items	[2]			(278)
Net realized gains (losses) recognized for fair value hedge				$ 22

[1]	Gains (losses) excluded from effectiveness testing includes the forward point on foreign currency forwards and time value change on foreign currency options which are reported in the consolidated statement of earnings as realized investment gains (losses). It also includes the change in the fair value of the interest rate swaptions related to the time value of the swaptions which is recognized as a component of other comprehensive income (loss).
[2]	Gains and losses on foreign currency forwards and options and related hedged items are reported in the consolidated statement of earnings as realized investment gains (losses). For interest rate swaptions and related hedged items, gains and losses included in the hedge assessment, premium amortization and time value amortization while the hedge items are still outstanding are reported within net investment income. The time value gains and losses for interest rate swaptions when the related hedged items are redeemed are reported in realized investment gains and losses consistent with the impact of the hedged item. For the years ended December 31, 2019 and 2018, gains and losses included in the hedge assessment on interest rate swaptions and related hedged items were immaterial.

DERIVATIVE INSTRUMENTS - Schedu

DERIVATIVE INSTRUMENTS - Schedule of Interest Rate Fair Value Hedges Hedged Items (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net derivatives notional amount		$ 61,695	$ 38,355
Fair value hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net derivatives notional amount		12,780	11,656
Interest rate swaptions \| Fair value hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net derivatives notional amount		243	500
Fixed maturity securities \| Interest rate swaptions
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Hedged Assets/ (Liabilities)	[1]	4,633	6,593
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of Hedged Assets/ (Liabilities)		$ 256	$ 294

[1]	The balance includes hedging adjustment on discontinued hedging relationships of $256 in 2019 and $294 in 2018 .

DERIVATIVE INSTRUMENTS - Deriva

DERIVATIVE INSTRUMENTS - Derivatives and Hedging Instruments Gain (Loss) Summary (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) reclassified from accumulated OCI into income, effective portion, net	[1]	$ (3)	$ 0	$ 0
Derivative gains (losses)		(174)	(224)	(109)
Unrealized foreign currency translation gains (losses) during period		252	232	286
Derivative and non-derivative hedging instruments gain loss recognized in other comprehensive income effective portion before tax	[2]	47	(38)	(34)
Cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) reclassified from accumulated OCI into income, effective portion, net	[1]	(2)	0	0
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)	[3]	(1)	0	0
Gain (loss) recognized in other comprehensive income on derivative (effective portion)	[2]	(4)	3	1
Cash flow hedges \| Foreign currency swaps \| Variable Interest Entity
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) reclassified from accumulated OCI into income, effective portion, net	[1]	(2)	0	0
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)		(1)	0	0
Gain (loss) recognized in other comprehensive income on derivative (effective portion)	[2]	(4)	3	1
Fair value hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) reclassified from accumulated OCI into income, effective portion, net	[1]	(1)	0	0
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)		(69)	(112)	(169)
Gain (loss) recognized in other comprehensive income on derivative (effective portion)	[2]	(8)	(1)	0
Fair value hedges \| Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)	[3]	(62)	(116)	(180)
Fair value hedges \| Foreign currency options
Derivative Instruments, Gain (Loss) [Line Items]
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)	[3]	(7)	4	11
Fair value hedges \| Interest rate swaptions
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) reclassified from accumulated OCI into income, effective portion, net	[1],[3]	(1)	0	0
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)	[3]	0	0	0
Gain (loss) recognized in other comprehensive income on derivative (effective portion)	[2],[3]	(8)	(1)	0
Net investment hedge
Derivative Instruments, Gain (Loss) [Line Items]
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)		6	0	0
Unrealized foreign currency translation gains (losses) during period	[2]	59	(40)	(35)
Net investment hedge \| Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)		10	0	0
Unrealized foreign currency translation gains (losses) during period	[2]	83	0	(25)
Net investment hedge \| Foreign currency options
Derivative Instruments, Gain (Loss) [Line Items]
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)		(4)	0	0
Unrealized foreign currency translation gains (losses) during period	[2]	0	(8)	5
Net investment hedge \| Non-derivative hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net realized investment gain (loss) recognized in income on derivative (ineffective portion)		0	0	0
Unrealized foreign currency translation gains (losses) during period	[2]	(24)	(32)	(15)
Non-qualifying strategies
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net		(110)	(112)	60
Non-qualifying strategies \| Foreign currency swaps \| Consolidated Entity Excluding Variable Interest Entities (VIE)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net		90	(40)	9
Non-qualifying strategies \| Foreign currency swaps \| Variable Interest Entity
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net		(68)	60	44
Non-qualifying strategies \| Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net		(148)	(135)	8
Non-qualifying strategies \| Credit default swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net		0	0	(1)
Non-qualifying strategies \| Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net		$ 17	$ 3	$ 0

[1]	Cash flow hedge items and the change in the fair value of interest rate swaptions related to the time value of the swaptions in fair value hedges are recorded as unrealized gains (losses) on derivatives and net investment hedge items are recorded in the unrealized foreign currency translation gains (losses) line in the consolidated statement of comprehensive income (loss).
[2]	Impact of cash flow hedges reported as realized investment gains (losses) includes an immaterial amount of gains or losses reclassified from accumulated other comprehensive income (loss) into earnings. It also includes an immaterial amount excluded from effectiveness testing during the years ended December 31, 2019 , 2018 and 2017 , respectively.
[3]	Impact shown net of effect of hedged items (see Fair Value Hedges section of this Note 4 for further detail)

DERIVATIVE INSTRUMENTS - Offset

DERIVATIVE INSTRUMENTS - Offsetting of Financial Assets and Derivative Assets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	$ 313	$ 234
Gross amount of liabilities offset in balance sheet	0	0
Net amount of derivative assets presented in balance sheet	313	234
Financial instruments, amounts not offset	(190)	(152)
Derivative, collateral, obligation to return securities	(7)	(23)
Derivative, collateral, obligation to return cash	(113)	(58)
Derivative asset, fair value, amount offset against collateral, subject to master netting agreement	3	1
Derivative asset, not subject to master netting arrangement	169	183
Derivative asset, fair value, amount offset against collateral, not subject to master netting agreement	169	183
Derivative asset, fair value, gross asset including not subject to master netting arrangement	482	417
Net amounts of derivative assets presented in balance sheet	482	417
Derivative asset, fair value, amount offset against collateral	172	184
Gross amounts of recognized financial instruments	2,342	1,446
Gross amounts offest in balance sheet	0	0
Net amounts of assets presented in balance sheet	2,342	1,446
Carrying value of financial instruments not offset in balance sheet	(190)	(152)
Securities collateral, not offset in balance sheet	(7)	(23)
Cash collateral, not offset in balance sheet	(1,973)	(1,087)
Financial instruments, amount of assets offset against collateral	172	184
Over the Counter - Bilateral
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	310	231
Gross amount of liabilities offset in balance sheet	0	0
Net amount of derivative assets presented in balance sheet	310	231
Financial instruments, amounts not offset	(190)	(152)
Derivative, collateral, obligation to return securities	(7)	(23)
Derivative, collateral, obligation to return cash	(113)	(55)
Derivative asset, fair value, amount offset against collateral, subject to master netting agreement	0	1
Derivative asset, not subject to master netting arrangement	169	183
Derivative asset, fair value, amount offset against collateral, not subject to master netting agreement	169	183
Other the Counter - Cleared
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	3	3
Gross amount of liabilities offset in balance sheet	0	0
Net amount of derivative assets presented in balance sheet	3	3
Financial instruments, amounts not offset	0	0
Derivative, collateral, obligation to return securities	0	0
Derivative, collateral, obligation to return cash	0	(3)
Derivative asset, fair value, amount offset against collateral, subject to master netting agreement	3	0
Securities Lending and Similar Arrangements
Offsetting Assets [Line Items]
Gross amounts of recognized financial instruments	1,860	1,029
Gross amounts offest in balance sheet	0	0
Net amounts of assets presented in balance sheet	1,860	1,029
Carrying value of financial instruments not offset in balance sheet	0	0
Securities collateral, not offset in balance sheet	0	0
Cash collateral, not offset in balance sheet	(1,860)	(1,029)
Financial instruments, amount of assets offset against collateral	$ 0	$ 0

DERIVATIVE INSTRUMENTS - Offs_2

DERIVATIVE INSTRUMENTS - Offsetting of Financial Liabilities and Derivative Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Offsetting Liabilities [Line Items]
Gross amount of recognized derivative liabilities	$ 460	$ 285
Gross amount of assets offset in balance sheet	0	0
Derivative liability, fair value, amount not offset against collateral	460	285
Financial instruments, amounts not offset	(190)	(152)
Derivative, collateral, right to reclaim securities	(222)	(37)
Derivative, collateral, right to reclaim cash	(33)	(68)
Derivative liability, fair value, amount offset against collateral, subject to master netting agreement	15	28
Derivative liability, not subject to master netting arrangement	126	102
Derivative liability, fair value, amount offset against collateral, not subject to master netting agreement	126	102
Derivative liability, fair value, gross liability including not subject to master netting arrangement	586	387
Net amount of derivative liabilities presented in balance sheet	586	387
Derivative liability, fair value, amount offset against collateral	141	130
Gross amounts of recognized financial instruments, offsetting liabilities	2,462	1,439
Gross amounts offset in statement of financial position, offsetting liabilities	0	0
Net amounts of financial instruments presented in balance sheet, offsetting liabilities	2,462	1,439
Carrying value of financial instruments, liabilities not offset in balance sheet	(2,050)	(1,181)
Securities collateral, liabilities not offset in balance sheet	(222)	(37)
Cash collateral, liabilities not offset in balance sheet	(33)	(68)
Financial instruments, amount of liabilities offset against collateral	157	153
Over the Counter - Bilateral
Offsetting Liabilities [Line Items]
Gross amount of recognized derivative liabilities	459	285
Gross amount of assets offset in balance sheet	0	0
Derivative liability, fair value, amount not offset against collateral	459	285
Financial instruments, amounts not offset	(190)	(152)
Derivative, collateral, right to reclaim securities	(222)	(37)
Derivative, collateral, right to reclaim cash	(32)	(68)
Derivative liability, fair value, amount offset against collateral, subject to master netting agreement	15	28
Derivative liability, not subject to master netting arrangement	126	102
Derivative liability, fair value, amount offset against collateral, not subject to master netting agreement	126	102
Over the Counter- Cleared
Offsetting Liabilities [Line Items]
Gross amount of recognized derivative liabilities	1
Gross amount of assets offset in balance sheet	0
Derivative liability, fair value, amount not offset against collateral	1
Financial instruments, amounts not offset	0
Derivative, collateral, right to reclaim securities	0
Derivative, collateral, right to reclaim cash	(1)
Derivative liability, fair value, amount offset against collateral, subject to master netting agreement	0
Securities Lending and Similar Arrangements
Offsetting Liabilities [Line Items]
Gross amounts of recognized financial instruments, offsetting liabilities	1,876	1,052
Gross amounts offset in statement of financial position, offsetting liabilities	0	0
Net amounts of financial instruments presented in balance sheet, offsetting liabilities	1,876	1,052
Carrying value of financial instruments, liabilities not offset in balance sheet	(1,860)	(1,029)
Securities collateral, liabilities not offset in balance sheet	0	0
Cash collateral, liabilities not offset in balance sheet	0	0
Financial instruments, amount of liabilities offset against collateral	$ 16	$ 23

FAIR VALUE MEASUREMENTS - Fair

FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets:
Available for sale, fixed maturity securities	$ 91,262	$ 82,895
Equity securities	802	987
Other investments	628	152
Cash and cash equivalents	4,896	4,337
Asset derivatives	482	417
Total assets	98,070	88,788
Liabilities:
Liability derivatives	586	387
Total liabilities	586	387
Foreign currency swaps
Assets:
Asset derivatives	241	285
Liabilities:
Liability derivatives	204	234
Foreign currency forwards
Assets:
Asset derivatives	238	126
Liabilities:
Liability derivatives	377	151
Foreign currency options
Assets:
Asset derivatives		3
Liabilities:
Liability derivatives	5	1
Interest rate swaptions
Liabilities:
Liability derivatives		1
Interest rate swaps
Assets:
Asset derivatives	3	3
Government and agencies
Assets:
Available for sale, fixed maturity securities	36,400	34,342
Municipalities
Assets:
Available for sale, fixed maturity securities	1,847	1,863
Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	410	339
Public utilities
Assets:
Available for sale, fixed maturity securities	6,780	7,171
Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,042	1,260
Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	10,287	8,918
Other corporate
Assets:
Available for sale, fixed maturity securities	34,496	29,002
Level 1
Assets:
Available for sale, fixed maturity securities	34,878	32,993
Equity securities	642	874
Other investments	628	152
Cash and cash equivalents	4,896	4,337
Asset derivatives	0	0
Total assets	41,044	38,356
Liabilities:
Total liabilities	0	0
Level 1 \| Foreign currency swaps
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 1 \| Foreign currency forwards
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 1 \| Foreign currency options
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives	0	0
Level 1 \| Interest rate swaptions
Liabilities:
Liability derivatives		0
Level 1 \| Interest rate swaps
Assets:
Asset derivatives	0	0
Level 1 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	34,878	32,993
Level 1 \| Municipalities
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Public utilities
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	0	0
Level 1 \| Other corporate
Assets:
Available for sale, fixed maturity securities	0	0
Level 2
Assets:
Available for sale, fixed maturity securities	55,697	49,380
Equity securities	80	67
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	313	235
Total assets	56,090	49,682
Liabilities:
Total liabilities	460	285
Level 2 \| Foreign currency swaps
Assets:
Asset derivatives	72	103
Liabilities:
Liability derivatives	78	132
Level 2 \| Foreign currency forwards
Assets:
Asset derivatives	238	126
Liabilities:
Liability derivatives	377	151
Level 2 \| Foreign currency options
Assets:
Asset derivatives		3
Liabilities:
Liability derivatives	5	1
Level 2 \| Interest rate swaptions
Liabilities:
Liability derivatives		1
Level 2 \| Interest rate swaps
Assets:
Asset derivatives	3	3
Level 2 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	1,522	1,349
Level 2 \| Municipalities
Assets:
Available for sale, fixed maturity securities	1,847	1,863
Level 2 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	232	162
Level 2 \| Public utilities
Assets:
Available for sale, fixed maturity securities	6,556	7,062
Level 2 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	1,042	1,260
Level 2 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	10,264	8,895
Level 2 \| Other corporate
Assets:
Available for sale, fixed maturity securities	34,234	28,789
Level 3
Assets:
Available for sale, fixed maturity securities	687	522
Equity securities	80	46
Other investments	0	0
Cash and cash equivalents	0	0
Asset derivatives	169	182
Total assets	936	750
Liabilities:
Total liabilities	126	102
Level 3 \| Foreign currency swaps
Assets:
Asset derivatives	169	182
Liabilities:
Liability derivatives	126	102
Level 3 \| Foreign currency forwards
Assets:
Asset derivatives	0	0
Liabilities:
Liability derivatives	0	0
Level 3 \| Foreign currency options
Assets:
Asset derivatives		0
Liabilities:
Liability derivatives	0	0
Level 3 \| Interest rate swaptions
Liabilities:
Liability derivatives		0
Level 3 \| Interest rate swaps
Assets:
Asset derivatives	0	0
Level 3 \| Government and agencies
Assets:
Available for sale, fixed maturity securities	0	0
Level 3 \| Municipalities
Assets:
Available for sale, fixed maturity securities	0	0
Level 3 \| Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities	178	177
Level 3 \| Public utilities
Assets:
Available for sale, fixed maturity securities	224	109
Level 3 \| Sovereign and supranational
Assets:
Available for sale, fixed maturity securities	0	0
Level 3 \| Banks/financial institutions
Assets:
Available for sale, fixed maturity securities	23	23
Level 3 \| Other corporate
Assets:
Available for sale, fixed maturity securities	$ 262	$ 213

FAIR VALUE MEASUREMENTS - Fai_2

FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Carried at Cost or Amortized Cost (Details) - USD ($) $ in Millions	Dec. 31, 2019		Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	$ 1,477		$ 787
Assets:
Securities held to maturity, fixed maturities, amortized cost	30,085		30,318
Held to maturity, fixed maturity securities, fair value	37,594		36,722
Commercial mortgage and other loans	9,569		6,919
Loans Receivable, Fair Value Disclosure	9,648		6,893
Other investments, carried at amortized cost	30	[1]	26	[2]
Other investments, carried at amortized cost, fair value	30	[1]	26	[2]
Total financial instruments, assets, not carried at fair value	39,684		37,263
Assets, fair value disclosure, financial instruments, carried at cost	47,272		43,641
Liabilities:
Other policyholders' funds	7,317		7,146
Other policyholders' funds fair value disclosure	7,234		7,067
Notes payable	6,408		5,765
Notes payable, fair value disclosure	6,935		5,876
Total financial instrument liabilities not carried at fair value	13,725		12,911
Liabilities fair value disclosure financial instruments carried at cost	14,169		12,943
Government and agencies
Assets:
Securities held to maturity, fixed maturities, amortized cost	22,241		21,712
Held to maturity, fixed maturity securities, fair value	28,291		27,038
Municipalities
Assets:
Securities held to maturity, fixed maturities, amortized cost	821		359
Held to maturity, fixed maturity securities, fair value	1,083		469
Mortgage- and asset-backed securities
Assets:
Securities held to maturity, fixed maturities, amortized cost	16		14
Held to maturity, fixed maturity securities, fair value	17		15
Public utilities
Assets:
Securities held to maturity, fixed maturities, amortized cost	2,535		2,727
Held to maturity, fixed maturity securities, fair value	2,954		2,973
Sovereign and supranational
Assets:
Securities held to maturity, fixed maturities, amortized cost	1,123		1,551
Held to maturity, fixed maturity securities, fair value	1,320		1,840
Banks/financial institutions
Assets:
Securities held to maturity, fixed maturities, amortized cost	916		1,445
Held to maturity, fixed maturity securities, fair value	1,018		1,583
Other corporate
Assets:
Securities held to maturity, fixed maturities, amortized cost	2,433		2,510
Held to maturity, fixed maturity securities, fair value	2,911		2,804
Policy loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	250		232
Equity method investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	569		377
Level 1
Assets:
Held to maturity, fixed maturity securities, fair value	27,937		27,030
Loans Receivable, Fair Value Disclosure	0		0
Other investments, carried at amortized cost, fair value	0	[1]	0	[2]
Assets, fair value disclosure, financial instruments, carried at cost	27,937		27,030
Liabilities:
Other policyholders' funds fair value disclosure	0		0
Notes payable, fair value disclosure	0		0
Liabilities fair value disclosure financial instruments carried at cost	0		0
Level 1 \| Government and agencies
Assets:
Held to maturity, fixed maturity securities, fair value	27,937		27,030
Level 1 \| Municipalities
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 1 \| Mortgage- and asset-backed securities
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 1 \| Public utilities
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 1 \| Sovereign and supranational
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 1 \| Banks/financial institutions
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 1 \| Other corporate
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 2
Assets:
Held to maturity, fixed maturity securities, fair value	9,647		9,677
Loans Receivable, Fair Value Disclosure	0		0
Other investments, carried at amortized cost, fair value	30	[1]	26	[2]
Assets, fair value disclosure, financial instruments, carried at cost	9,677		9,703
Liabilities:
Other policyholders' funds fair value disclosure	0		0
Notes payable, fair value disclosure	6,663		5,606
Liabilities fair value disclosure financial instruments carried at cost	6,663		5,606
Level 2 \| Government and agencies
Assets:
Held to maturity, fixed maturity securities, fair value	354		8
Level 2 \| Municipalities
Assets:
Held to maturity, fixed maturity securities, fair value	1,083		469
Level 2 \| Mortgage- and asset-backed securities
Assets:
Held to maturity, fixed maturity securities, fair value	7		0
Level 2 \| Public utilities
Assets:
Held to maturity, fixed maturity securities, fair value	2,954		2,973
Level 2 \| Sovereign and supranational
Assets:
Held to maturity, fixed maturity securities, fair value	1,320		1,840
Level 2 \| Banks/financial institutions
Assets:
Held to maturity, fixed maturity securities, fair value	1,018		1,583
Level 2 \| Other corporate
Assets:
Held to maturity, fixed maturity securities, fair value	2,911		2,804
Level 3
Assets:
Held to maturity, fixed maturity securities, fair value	10		15
Loans Receivable, Fair Value Disclosure	9,648		6,893
Other investments, carried at amortized cost, fair value	0	[1]	0	[2]
Assets, fair value disclosure, financial instruments, carried at cost	9,658		6,908
Liabilities:
Other policyholders' funds fair value disclosure	7,234		7,067
Notes payable, fair value disclosure	272		270
Liabilities fair value disclosure financial instruments carried at cost	7,506		7,337
Level 3 \| Government and agencies
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 3 \| Municipalities
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 3 \| Mortgage- and asset-backed securities
Assets:
Held to maturity, fixed maturity securities, fair value	10		15
Level 3 \| Public utilities
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 3 \| Sovereign and supranational
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 3 \| Banks/financial institutions
Assets:
Held to maturity, fixed maturity securities, fair value	0		0
Level 3 \| Other corporate
Assets:
Held to maturity, fixed maturity securities, fair value	$ 0		$ 0

[1]	Excludes policy loans of $250 and equity method investments of $569 , at carrying value
[2]	Excludes policy loans of $232 and equity method investments of $377 , at carrying value

FAIR VALUE MEASUREMENTS - Fai_3

FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets by Pricing Source, Securities Carried at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	$ 91,262	$ 82,895
Equity securities	802	987
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	34,878	32,993
Equity securities	642	874
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	55,697	49,380
Equity securities	80	67
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	687	522
Equity securities	80	46
Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity securities	722	941
Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity securities	642	874
Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity securities	80	67
Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity securities	0	0
Net asset value valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity securities	80	46
Net asset value valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity securities	0	0
Net asset value valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity securities	0	0
Net asset value valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity securities	80	46
Government and agencies
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	36,400	34,342
Government and agencies \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	34,878	32,993
Government and agencies \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,522	1,349
Government and agencies \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Government and agencies \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	36,400	34,342
Government and agencies \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	34,878	32,993
Government and agencies \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,522	1,349
Government and agencies \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Municipalities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,847	1,863
Municipalities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Municipalities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,847	1,863
Municipalities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Municipalities \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,847	1,863
Municipalities \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Municipalities \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,847	1,863
Municipalities \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Mortgage- and asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	410	339
Mortgage- and asset-backed securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Mortgage- and asset-backed securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	232	162
Mortgage- and asset-backed securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	178	177
Mortgage- and asset-backed securities \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	232	162
Mortgage- and asset-backed securities \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Mortgage- and asset-backed securities \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	232	162
Mortgage- and asset-backed securities \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Mortgage- and asset-backed securities \| Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	178	177
Mortgage- and asset-backed securities \| Consensus pricing valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Mortgage- and asset-backed securities \| Consensus pricing valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Mortgage- and asset-backed securities \| Consensus pricing valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	178	177
Public utilities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	6,780	7,171
Public utilities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Public utilities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	6,556	7,062
Public utilities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	224	109
Public utilities \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	6,556	7,062
Public utilities \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Public utilities \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	6,556	7,062
Public utilities \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Public utilities \| Discounted cash flow technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	224	109
Public utilities \| Discounted cash flow technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Public utilities \| Discounted cash flow technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Public utilities \| Discounted cash flow technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	224	109
Sovereign and supranational
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,042	1,260
Sovereign and supranational \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Sovereign and supranational \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,042	1,260
Sovereign and supranational \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Sovereign and supranational \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,042	1,260
Sovereign and supranational \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Sovereign and supranational \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	1,042	1,260
Sovereign and supranational \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Banks/financial institutions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	10,287	8,918
Banks/financial institutions \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Banks/financial institutions \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	10,264	8,895
Banks/financial institutions \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	23	23
Banks/financial institutions \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	10,264	8,895
Banks/financial institutions \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Banks/financial institutions \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	10,264	8,895
Banks/financial institutions \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Banks/financial institutions \| Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	23	23
Banks/financial institutions \| Consensus pricing valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Banks/financial institutions \| Consensus pricing valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Banks/financial institutions \| Consensus pricing valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	23	23
Other corporate
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	34,496	29,002
Other corporate \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Other corporate \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	34,234	28,789
Other corporate \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	262	213
Other corporate \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	34,234	28,789
Other corporate \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Other corporate \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	34,234	28,789
Other corporate \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Other corporate \| Discounted cash flow technique
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	262	213
Other corporate \| Discounted cash flow technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Other corporate \| Discounted cash flow technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	0	0
Other corporate \| Discounted cash flow technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available for sale, fixed maturity securities	$ 262	$ 213

FAIR VALUE MEASUREMENTS - Fai_4

FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets by Pricing Source, Securities Carried at Amortized Cost (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	$ 37,594	$ 36,722
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	27,937	27,030
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	9,647	9,677
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	10	15
Government and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	28,291	27,038
Government and agencies \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	27,937	27,030
Government and agencies \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	354	8
Government and agencies \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Government and agencies \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	28,291	27,038
Government and agencies \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	27,937	27,030
Government and agencies \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	354	8
Government and agencies \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Municipalities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,083	469
Municipalities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Municipalities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,083	469
Municipalities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Municipalities \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,083	469
Municipalities \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Municipalities \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,083	469
Municipalities \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Mortgage- and asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	17	15
Mortgage- and asset-backed securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Mortgage- and asset-backed securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	7	0
Mortgage- and asset-backed securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	10	15
Mortgage- and asset-backed securities \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	7
Mortgage- and asset-backed securities \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0
Mortgage- and asset-backed securities \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	7
Mortgage- and asset-backed securities \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0
Mortgage- and asset-backed securities \| Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	10	15
Mortgage- and asset-backed securities \| Consensus pricing valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Mortgage- and asset-backed securities \| Consensus pricing valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Mortgage- and asset-backed securities \| Consensus pricing valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	10	15
Public utilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	2,954	2,973
Public utilities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Public utilities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	2,954	2,973
Public utilities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Public utilities \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	2,954	2,973
Public utilities \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Public utilities \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	2,954	2,973
Public utilities \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Sovereign and supranational
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,320	1,840
Sovereign and supranational \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Sovereign and supranational \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,320	1,840
Sovereign and supranational \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Sovereign and supranational \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,320	1,840
Sovereign and supranational \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Sovereign and supranational \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,320	1,840
Sovereign and supranational \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Banks/financial institutions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,018	1,583
Banks/financial institutions \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Banks/financial institutions \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,018	1,583
Banks/financial institutions \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Banks/financial institutions \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,018	1,583
Banks/financial institutions \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Banks/financial institutions \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,018	1,583
Banks/financial institutions \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Other corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	2,911	2,804
Other corporate \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Other corporate \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	2,911	2,804
Other corporate \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Other corporate \| Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	2,911	2,804
Other corporate \| Third party pricing vendor valuation technique \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Other corporate \| Third party pricing vendor valuation technique \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	2,911	2,804
Other corporate \| Third party pricing vendor valuation technique \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	$ 0	$ 0

FAIR VALUE MEASUREMENTS - Chang

FAIR VALUE MEASUREMENTS - Changes in Investments and Derivatives Carried at Fair Value Classified as Level 3 (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		$ 648		$ 453
Realized investment gains (losses) included in earnings		(34)		52
Unrealized gains (losses) included in other comprehensive income (loss)		12		6
Purchases		247		127
Issuances		0		0
Sales		(41)		0
Settlements		(6)		(6)
Transfers into Level 3		142		16
Transfers out of Level 3		(158)		0
Balance, end of period		810		648
Change in unrealized gains (losses) still held		(33)		52
Foreign currency swaps
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	[1]	80		22
Realized gains (losses) included in earnings	[1]	(33)		54
Unrealized gains (losses) included in other comprehensive income (loss)	[1]	(4)		4
Purchases	[1]	0		0
Issuances	[1]	0		0
Sales	[1]	0		0
Settlements	[1]	0		0
Transfers into Level 3	[1]	0		0
Transfers out of Level 3	[1]	0		0
Balance, end of period	[1]	43		80
Change in unrealized gains (losses) still held	[1]	(33)		54
Credit default swaps
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	[1]	0		1
Realized gains (losses) included in earnings	[1]	0		(1)
Unrealized gains (losses) included in other comprehensive income (loss)	[1]	0		0
Purchases	[1]	0		0
Issuances	[1]	0		0
Sales	[1]	0		0
Settlements	[1]	0		0
Transfers into Level 3	[1]	0		0
Transfers out of Level 3	[1]	0		0
Balance, end of period	[1]	0		0
Change in unrealized gains (losses) still held	[1]	0		(1)
Fixed maturity securities \| Mortgage- and asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		177		175
Realized investment gains (losses) included in earnings		0		0
Unrealized gains (losses) included in other comprehensive income (loss)		1		2
Purchases		0		0
Issuances		0		0
Sales		0		0
Settlements		0		0
Transfers into Level 3		0		0
Transfers out of Level 3		0		0
Balance, end of period		178		177
Change in unrealized gains (losses) still held		0		0
Fixed maturity securities \| Public utilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		109		68
Realized investment gains (losses) included in earnings		0		0
Unrealized gains (losses) included in other comprehensive income (loss)		6		1
Purchases		48		40
Issuances		0		0
Sales		(24)		0
Settlements		(6)		0
Transfers into Level 3		116	[2]	0
Transfers out of Level 3		(25)	[2]	0
Balance, end of period		224		109
Change in unrealized gains (losses) still held		0		0
Fixed maturity securities \| Banks/financial institutions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		23		25
Realized investment gains (losses) included in earnings		0		0
Unrealized gains (losses) included in other comprehensive income (loss)		1		(2)
Purchases		0		0
Issuances		0		0
Sales		0		0
Settlements		0		0
Transfers into Level 3		0		0
Transfers out of Level 3		(1)		0
Balance, end of period		23		23
Change in unrealized gains (losses) still held		0		0
Fixed maturity securities \| Other corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		213		146
Realized investment gains (losses) included in earnings		(1)		0
Unrealized gains (losses) included in other comprehensive income (loss)		8		1
Purchases		165		56
Issuances		0		0
Sales		(17)		0
Settlements		0		(6)
Transfers into Level 3		26	[2]	16
Transfers out of Level 3		(132)	[2],[3]	0
Balance, end of period		262		213
Change in unrealized gains (losses) still held		0		0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		46		16
Realized investment gains (losses) included in earnings		0		(1)
Unrealized gains (losses) included in other comprehensive income (loss)		0		0
Purchases		34		31
Issuances		0		0
Sales		0		0
Settlements		0		0
Transfers into Level 3		0		0
Transfers out of Level 3		0		0
Balance, end of period		80		46
Change in unrealized gains (losses) still held		$ 0		$ (1)

[1]	Derivative assets and liabilities are presented net
[2]	Transfer due to sector classification change
[3]	Transfer due to availability of observable market inputs

FAIR VALUE MEASUREMENTS - Fai_5

FAIR VALUE MEASUREMENTS - Fair Value Measurement Inputs and Valuation Techniques (Details) $ in Millions		Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		$ 91,262	$ 82,895
Equity securities		802	987
Asset derivatives		482	417
Liability derivatives		586	387
Assets, fair value		98,070	88,788
Liabilities, fair value		586	387
Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		687	522
Equity securities		80	46
Asset derivatives		169	182
Assets, fair value		936	750
Liabilities, fair value		126	102
Net asset value valuation technique
Fair Value Measurement Inputs and Valuation Technique
Equity securities		80	46
Net asset value valuation technique \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Equity securities		80	46
Foreign currency swaps
Fair Value Measurement Inputs and Valuation Technique
Asset derivatives		241	285
Liability derivatives		204	234
Foreign currency swaps \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Asset derivatives		169	182
Liability derivatives		126	102
Foreign currency swaps \| Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads \| Discounted cash flow technique \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Asset derivatives		106	125
Liability derivatives		118	98
Foreign currency swaps \| Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) \| Discounted cash flow technique \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Asset derivatives		63	57
Liability derivatives		$ 8	$ 4
Foreign currency swaps \| Credit Spread \| Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads \| Lower Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input		0.0010	0.0019
Derivative liability, measurement input		0.0013	0.0028
Foreign currency swaps \| Credit Spread \| Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads \| Upper Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input		0.0100	0.0120
Derivative liability, measurement input		0.0159	0.0211
Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		$ 38,281	$ 33,995
Equity securities		$ 144	$ 346
Dollar-denominated \| Foreign currency swaps \| Discount Rate \| Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads \| Lower Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[1]	0.0189	0.0275
Derivative liability, measurement input	[1]	0.0189	0.0275
Dollar-denominated \| Foreign currency swaps \| Discount Rate \| Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads \| Upper Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[1]	0.0209	0.0284
Derivative liability, measurement input	[1]	0.0209	0.0284
Dollar-denominated \| Foreign currency swaps \| Discount Rate \| Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) \| Lower Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[1]	0.0189	0.0275
Derivative liability, measurement input	[1]	0.0189	0.0275
Dollar-denominated \| Foreign currency swaps \| Discount Rate \| Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) \| Upper Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[1]	0.0209	0.0284
Derivative liability, measurement input	[1]	0.0209	0.0284
Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		$ 52,981	$ 48,900
Equity securities		$ 658	$ 641
Yen-denominated \| Foreign currency swaps \| Discount Rate \| Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads \| Lower Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[2]	0.0012	0.0018
Derivative liability, measurement input	[2]	0.0012	0.0018
Yen-denominated \| Foreign currency swaps \| Discount Rate \| Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads \| Upper Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[2]	0.0043	0.0071
Derivative liability, measurement input	[2]	0.0043	0.0071
Yen-denominated \| Foreign currency swaps \| Discount Rate \| Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) \| Lower Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[2]	0.0012	0.0018
Derivative liability, measurement input	[2]	0.0012	0.0018
Yen-denominated \| Foreign currency swaps \| Discount Rate \| Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) \| Upper Limit \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[2]	0.0043	0.0071
Derivative liability, measurement input	[2]	0.0043	0.0071
Mortgage- and asset-backed securities
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		$ 410	$ 339
Mortgage- and asset-backed securities \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		178	177
Mortgage- and asset-backed securities \| Consensus pricing valuation technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		178	177
Mortgage- and asset-backed securities \| Consensus pricing valuation technique \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		178	177
Mortgage- and asset-backed securities \| Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		156	162
Mortgage- and asset-backed securities \| Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		254	177
Banks/financial institutions
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		10,287	8,918
Banks/financial institutions \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		23	23
Banks/financial institutions \| Consensus pricing valuation technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		23	23
Banks/financial institutions \| Consensus pricing valuation technique \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		23	23
Banks/financial institutions \| Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		3,521	3,214
Banks/financial institutions \| Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		6,766	5,704
Public utilities
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		6,780	7,171
Public utilities \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		224	109
Public utilities \| Discounted cash flow technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		224	109
Public utilities \| Discounted cash flow technique \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		224	109
Public utilities \| Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		4,519	5,163
Public utilities \| Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		2,261	2,008
Other corporate
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		34,496	29,002
Other corporate \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		262	213
Other corporate \| Discounted cash flow technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		262	213
Other corporate \| Discounted cash flow technique \| Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		262	213
Other corporate \| Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		28,253	23,545
Other corporate \| Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		$ 6,243	$ 5,457

[1]	Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps
[2]	Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps

FAIR VALUE MEASUREMENTS - Addit

FAIR VALUE MEASUREMENTS - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	$ 0	$ 0
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	$ 0	$ 0

DEFERRED POLICY ACQUISITION C_3

DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Additional Information (Detail) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Policy Acquisition Costs Disclosures [Abstract]
Capitalization of deferred policy acquisition costs	$ 1.5	$ 1.5	$ 1.5
Commissions deferred as a percentage of total acquisition costs	74.00%	72.00%	72.00%
Personnel, compensation and benefit expenses as a percentage of insurance expenses	57.00%	54.00%	56.00%

DEFERRED POLICY ACQUISITION C_4

DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Rollforward of Deferred Policy Acquisition Costs by Segment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred policy acquisition costs:
Balance, beginning of year	$ 9,875
Capitalization	1,500	$ 1,500	$ 1,500
Amortization	(1,282)	(1,245)	(1,132)
Balance, end of year	10,128	9,875
Aflac Japan
Deferred policy acquisition costs:
Balance, beginning of year	6,384	6,150
Capitalization	825	833
Amortization	(709)	(710)	(630)
Foreign currency translation and other	84	111
Balance, end of year	6,584	6,384	6,150
Aflac U.S.
Deferred policy acquisition costs:
Balance, beginning of year	3,491	3,355
Capitalization	626	669
Amortization	(573)	(534)	(502)
Foreign currency translation and other	0	1
Balance, end of year	$ 3,544	$ 3,491	$ 3,355

DEFERRED POLICY ACQUISITION C_5

DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Advertising Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Advertising Costs [Line Items]
Advertising expense	$ 219	$ 218	$ 210
Aflac Japan
Advertising Costs [Line Items]
Advertising expense	101	108	100
Aflac U.S.
Advertising Costs [Line Items]
Advertising expense	$ 118	$ 110	$ 110

DEFERRED POLICY ACQUISITION C_6

DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Depreciation and Other Amortization Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Policy Acquisition Costs Disclosures [Abstract]
Depreciation expense	$ 40	$ 48	$ 50
Other amortization expense	1	1	3
Total depreciation and other amortization expense	$ 41	$ 49	$ 53

POLICY LIABILITIES - Additional

POLICY LIABILITIES - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Future Policy Benefit, by Product Segment [Line Items]
Percentage of future policy benefits out of policy liabilities	85.00%
Percentage of unpaid policy claims out of policy liabilities	4.00%
Percentage of unearned premiums out of policy liabilities	4.00%
Percentage of other poliyholders' funds out of policy liabilities	7.00%
Percentage of advanced premiums to unearned premiums	64.00%	69.00%
Percentage of annuities to other policyholders' fund	97.00%	97.00%
Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate	3.20%	3.30%	3.40%
Aflac U.S.
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate	5.30%	5.30%	5.40%
Health insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Prior year claims and claims adjustment expense	$ (552)	$ (563)	$ (518)
Health insurance \| Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Prior year claims and claims adjustment expense	$ (395)
Percentage of total prior year claims and claims adjustment expense	72.00%
Liability for unpaid claims and claims adjustment expense, foreign currency translation gain (loss)	$ 5
Prior year claims and claims adjustment expense excluding effect of foreign currency	$ (390)
Percentage of total prior year claims and claims adjustment expense excluding effect of foreign currency	71.00%

POLICY LIABILITIES - Liability

POLICY LIABILITIES - Liability for Future Policy Benefits (Detail) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 90,335	$ 86,368
Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		3.20%	3.30%	3.40%
Aflac U.S.
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		5.30%	5.30%	5.40%
Intercompany eliminations
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	[1]	$ (532)	$ (583)
Liability for future policy benefits, interest rate		2.00%
Health insurance \| Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 50,941	49,496
Health insurance \| Aflac Japan \| Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		0.60%
Health insurance \| Aflac Japan \| Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		6.75%
Health insurance \| Aflac U.S.
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 8,646	8,442
Health insurance \| Aflac U.S. \| Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		3.00%
Health insurance \| Aflac U.S. \| Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		7.00%
Life insurance \| Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 30,520	28,318
Life insurance \| Aflac Japan \| Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		1.00%
Life insurance \| Aflac Japan \| Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		4.50%
Life insurance \| Aflac U.S.
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts		$ 760	$ 695
Life insurance \| Aflac U.S. \| Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		2.50%
Life insurance \| Aflac U.S. \| Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for future policy benefits, interest rate		6.00%

[1]	Elimination entry necessary due to recapture of a portion of policy liabilities ceded externally, as a result of the reinsurance retrocession transaction as described in Note 8 of the Notes to the Consolidated Financial Statements

POLICY LIABILITIES - Changes in

POLICY LIABILITIES - Changes in Liability for Unpaid Policy Claims (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	$ 4,584	$ 4,392
Net balance, beginning of year	4,584
Less claims paid during the year on claims incurred during:
Net balance, end of year	4,659	4,584
Total liability for unpaid policy claims	4,659	4,584	$ 4,392
Health insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	3,952	3,884	3,707
Less reinsurance recoverables	27	30	27
Net balance, beginning of year	3,925	3,854	3,680
Add claims incurred during the year related to:
Current year	7,216	7,101	6,979
Prior years	(552)	(563)	(518)
Total incurred	6,664	6,538	6,461
Less claims paid during the year on claims incurred during:
Current year	4,715	4,612	4,530
Prior years	1,965	1,898	1,822
Total paid	6,680	6,510	6,352
Effect of foreign exchange rate changes on unpaid claims	29	43	65
Net balance, end of year	3,938	3,925	3,854
Add reinsurance recoverables	30	27	30
Total liability for unpaid policy claims	3,968	3,952	3,884
Life insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	632	508
Less claims paid during the year on claims incurred during:
Total liability for unpaid policy claims	$ 691	$ 632	$ 508

REINSURANCE Additional Informat

REINSURANCE Additional Information (Detail) $ in Millions, ¥ in Billions	12 Months Ended
	Dec. 31, 2019JPY (¥)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Effects of Reinsurance [Line Items]
Percent change in spot yen/dollar exchange rate		1.30%
Percent change in ceded reserves		1.40%
Aflac Japan
Effects of Reinsurance [Line Items]
Committed reinsurance facility \| ¥	¥ 110
Aflac Japan \| Closed block
Effects of Reinsurance [Line Items]
Reinsurance deferred profit liability		$ 1,000
Reinsurance recoverable		$ 970	$ 941

REINSURANCE Effect of Reinsuran

REINSURANCE Effect of Reinsurance on Premiums and Benefits and Claims (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effects of Reinsurance [Line Items]
Direct premium income									$ 19,122	$ 19,018	$ 18,875
Ceded premiums									(547)	(555)	(566)
Assumed premiums earned									205	214	222
Net premium income	$ 4,671	$ 4,736	$ 4,681	$ 4,691	$ 4,591	$ 4,636	$ 4,706	$ 4,745	18,780	18,677	18,531
Direct benefits and claims									12,237	12,293	12,486
Benefits and claims, net									11,942	12,000	12,181
All other
Effects of Reinsurance [Line Items]
Ceded premiums									(69)	(58)	(51)
Assumed premiums earned									5	6	6
Ceded benefits and claims									(57)	(44)	(44)
Assumed benefits and claims from other companies									1	2	3
Aflac Japan
Effects of Reinsurance [Line Items]
Net premium income									12,772	12,762	12,752
Benefits and claims, net									8,877	8,913	9,087
Aflac Japan \| Closed block
Effects of Reinsurance [Line Items]
Ceded premiums									(478)	(497)	(515)
Assumed premiums earned									200	208	216
Ceded benefits and claims									(433)	(450)	(473)
Assumed benefits and claims from other companies									194	209	209
Intercompany eliminations
Effects of Reinsurance [Line Items]
Ceded benefits and claims									41	43	51
Assumed benefits and claims from other companies									$ (41)	$ (53)	$ (51)

NOTES PAYABLE - Additional Info

NOTES PAYABLE - Additional Information (Detail) $ in Millions, ¥ in Billions	Apr. 12, 2019JPY (¥)	Sep. 30, 2019JPY (¥)	Oct. 31, 2018USD ($)series	Oct. 31, 2017JPY (¥)	Dec. 31, 2016USD ($)	Nov. 30, 2014USD ($)	Jun. 30, 2013USD ($)	Dec. 31, 2019USD ($)series	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2019JPY (¥)series	Dec. 31, 2018JPY (¥)	Oct. 31, 2018JPY (¥)series	Jan. 31, 2017JPY (¥)	Sep. 30, 2016USD ($)series	Mar. 31, 2015USD ($)	Mar. 31, 2015JPY (¥)	Nov. 30, 2014JPY (¥)	Jun. 30, 2013JPY (¥)	Feb. 29, 2012USD ($)	Feb. 29, 2012JPY (¥)	Aug. 31, 2010USD ($)	Dec. 31, 2009USD ($)
Debt Instrument [Line Items]
Operating Lease, Cost \| $								$ 54	$ 73	$ 75
Number of series of senior notes issued through a U.S. public debt offering (in series) \| series			3					4			4		3		2
Operating lease, payments \| $								$ 52
.500% senior notes due December 2029
Debt Instrument [Line Items]
Debt instrument, interest rate								0.50%			0.50%
Debt instrument, principal amount											¥ 12.6
.843% senior notes due December 2031
Debt Instrument [Line Items]
Debt instrument, interest rate								0.843%			0.843%
Debt instrument, principal amount											¥ 9.3
.934% senior notes due December 2034
Debt Instrument [Line Items]
Debt instrument, interest rate								0.934%			0.934%
Debt instrument, principal amount											¥ 9.8
1.122% senior notes due December 2039
Debt Instrument [Line Items]
Debt instrument, interest rate								1.122%			1.122%
Debt instrument, principal amount											¥ 6.3
Yen-denominated loans
Debt Instrument [Line Items]
Debt instrument, principal amount		¥ 30
Yen-denominated loan variable interest rate due September 2026
Debt Instrument [Line Items]
Debt instrument, interest rate								0.42%			0.42%	0.32%
Debt instrument, description of variable rate basis		bears interest at a rate per annum equal to the Tokyo interbank market rate (TIBOR), or alternate TIBOR, if applicable, plus the applicable TIBOR margin
Debt instrument, principal amount		¥ 5									¥ 5	¥ 5
Yen-denominated loan variable interest rate due September 2029
Debt Instrument [Line Items]
Debt instrument, interest rate								0.57%			0.57%	0.47%
Debt instrument, description of variable rate basis		bears interest at a rate per annum equal to the TIBOR, or alternate TIBOR, if applicable, plus the applicable TIBOR margin
Debt instrument, principal amount		¥ 25									¥ 25	¥ 25
.963% subordinated bonds due April 2049
Debt Instrument [Line Items]
Debt instrument, interest rate	0.963%							0.963%			0.963%
Debt instrument, description of variable rate basis	These bonds bear interest at a fixed rate of .963% per annum and then at six-month Euro Yen LIBOR plus an applicable spread on and after the day immediately following April 18, 2024.
Debt instrument, principal amount	¥ 30										¥ 30
4.750% senior notes due January 2049
Debt Instrument [Line Items]
Debt instrument, interest rate			4.75%					4.75%			4.75%	4.75%	4.75%
Debt instrument, redemption, description			These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the yield to maturity for a U.S.Treasury security with a maturity comparable to the remaining term of the notes, plus 25 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date.
Debt instrument, principal amount \| $			$ 550
1.159% senior notes due October 2030
Debt Instrument [Line Items]
Debt instrument, interest rate			1.159%					1.159%			1.159%	1.159%	1.159%
Debt instrument, principal amount											¥ 29.3	¥ 29.3	¥ 29.3
1.488% senior notes due October 2033
Debt Instrument [Line Items]
Debt instrument, interest rate			1.488%					1.488%			1.488%	1.488%	1.488%
Debt instrument, principal amount											¥ 15.2	¥ 15.2	¥ 15.2
1.750% senior notes due October 2038
Debt Instrument [Line Items]
Debt instrument, interest rate			1.75%					1.75%			1.75%	1.75%	1.75%
Debt instrument, principal amount											¥ 8.9	¥ 8.9	¥ 8.9
2.108% subordinated notes due October 2047
Debt Instrument [Line Items]
Debt instrument, interest rate				2.108%				2.108%			2.108%	2.108%
Debt instrument, redemption, description				The debentures are redeemable (i) at any time, in whole but not in part, upon the occurrence of certain tax events or certain rating agency events, as specified in the indenture governing the terms of the debentures or (ii) on or after October 23, 2027, in whole or in part, at a redemption price equal to their principal amount plus accrued and unpaid interest to, but excluding, the date of redemption.
Debt instrument, call date, earliest				Oct. 23, 2027
Debt instrument, interest rate terms				The debentures bear interest at an initial rate of 2.108% per annum through October 22, 2027, or earlier redemption. Thereafter, the rate of the interest of the debentures will be reset every five years at a rate of interest equal to the then-current JPY 5-year Swap Offered Rate plus 205 basis points.
Debt instrument, principal amount				¥ 60							¥ 60	¥ 60
.932% senior notes due January 2027
Debt Instrument [Line Items]
Debt instrument, interest rate								0.932%			0.932%	0.932%		0.932%
Debt instrument, principal amount											¥ 60	¥ 60		¥ 60
2.875% senior notes due October 2026
Debt Instrument [Line Items]
Debt instrument, interest rate								2.875%			2.875%	2.875%			2.875%
Debt instrument, principal amount \| $															$ 300
4.00% senior notes due October 2046
Debt Instrument [Line Items]
Debt instrument, interest rate								4.00%			4.00%	4.00%			4.00%
Debt instrument, principal amount \| $															$ 400
3.25% senior notes due March 2025
Debt Instrument [Line Items]
Debt instrument, interest rate								3.25%			3.25%	3.25%				3.25%	3.25%
Debt instrument effective principal amount after cross currency swap																	¥ 55
Debt instrument, principal amount \| $								$ 450								$ 450
Debt instrument, effective interest rate																0.82%	0.82%
3.625% senior notes due November 2024
Debt Instrument [Line Items]
Debt instrument, interest rate						3.625%		3.625%			3.625%	3.625%						3.625%
Debt instrument, redemption, description						These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the treasury rate plus 20 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date.
Debt instrument effective principal amount after cross currency swap																		¥ 85.3
Debt instrument, principal amount \| $						$ 750		$ 750
Debt instrument, effective interest rate						1.00%												1.00%
3.625% senior notes due June 2023
Debt Instrument [Line Items]
Debt instrument, interest rate							3.625%	3.625%			3.625%	3.625%							3.625%
Debt instrument, redemption, description							These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the treasury rate plus 20 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date.
Debt instrument effective principal amount after cross currency swap																			¥ 69.8
Debt instrument, principal amount \| $							$ 700	$ 700
Debt instrument, effective interest rate							1.50%												1.50%
4.00% senior notes due February 2022
Debt Instrument [Line Items]
Debt instrument, interest rate								4.00%			4.00%	4.00%								4.00%	4.00%
Debt instrument effective principal amount after cross currency swap																					¥ 27
Debt instrument, principal amount \| $								$ 350												$ 350
Debt instrument, effective interest rate																				2.07%	2.07%
6.90% senior notes due December 2039
Debt Instrument [Line Items]
Repayments of debt \| $					$ 176
Debt instrument, interest rate					6.90%			6.90%			6.90%	6.90%
Debt instrument, principal amount \| $																							$ 400
6.45% senior notes due August 2040
Debt Instrument [Line Items]
Repayments of debt \| $					$ 193
Debt instrument, interest rate					6.45%			6.45%			6.45%	6.45%
Debt instrument, principal amount \| $																						$ 450
Senior Notes due 2039 and 2040
Debt Instrument [Line Items]
Expense on extinguishment of debt \| $										$ 137
Senior Notes
Debt Instrument [Line Items]
Debt instrument, principal amount											¥ 38		¥ 53.4		$ 700
Notes Payable
Debt Instrument [Line Items]
Debt instrument, debt default, amount \| $								$ 0
Lower Limit \| Yen-denominated loan variable interest rate due September 2026
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		0.30%
Lower Limit \| Yen-denominated loan variable interest rate due September 2029
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		0.45%
Upper Limit \| Yen-denominated loan variable interest rate due September 2026
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		0.70%
Upper Limit \| Yen-denominated loan variable interest rate due September 2029
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		1.00%
Line of Credit
Debt Instrument [Line Items]
Debt instrument, debt default, amount \| $								$ 0

NOTES PAYABLE - Summary of Note

NOTES PAYABLE - Summary of Notes Payable (Detail) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Notes payable and lease obligations	[1]	$ 6,569	$ 5,778
Finance lease, liability		12	13
Operating lease, liability	[2]	149	0
4.00% senior notes due February 2022
Debt Instrument [Line Items]
Notes payable and lease obligations	[3]	348	348
3.625% senior notes due June 2023
Debt Instrument [Line Items]
Notes payable and lease obligations		698	698
3.625% senior notes due November 2024
Debt Instrument [Line Items]
Notes payable and lease obligations		747	746
3.25% senior notes due March 2025
Debt Instrument [Line Items]
Notes payable and lease obligations		448	447
2.875% senior notes due October 2026
Debt Instrument [Line Items]
Notes payable and lease obligations		298	297
6.90% senior notes due December 2039
Debt Instrument [Line Items]
Notes payable and lease obligations		220	220
6.45% senior notes due August 2040
Debt Instrument [Line Items]
Notes payable and lease obligations		254	254
4.00% senior notes due October 2046
Debt Instrument [Line Items]
Notes payable and lease obligations		394	394
4.750% senior notes due January 2049
Debt Instrument [Line Items]
Notes payable and lease obligations		541	540
.932% senior notes due January 2027
Debt Instrument [Line Items]
Notes payable and lease obligations		545	538
.500% senior notes due December 2029
Debt Instrument [Line Items]
Notes payable and lease obligations		114	0
1.159% senior notes due October 2030
Debt Instrument [Line Items]
Notes payable and lease obligations		266	262
.843% senior notes due December 2031
Debt Instrument [Line Items]
Notes payable and lease obligations		84	0
1.488% senior notes due October 2033
Debt Instrument [Line Items]
Notes payable and lease obligations		138	136
.934% senior notes due December 2034
Debt Instrument [Line Items]
Notes payable and lease obligations		88	0
1.750% senior notes due October 2038
Debt Instrument [Line Items]
Notes payable and lease obligations		81	79
1.122% senior notes due December 2039
Debt Instrument [Line Items]
Notes payable and lease obligations		57	0
2.108% subordinated notes due October 2047
Debt Instrument [Line Items]
Notes payable and lease obligations		543	536
.963% subordinated bonds due April 2049
Debt Instrument [Line Items]
Notes payable and lease obligations		272	0
Yen-denominated loan variable interest rate due September 2026
Debt Instrument [Line Items]
Notes payable and lease obligations		45	45
Yen-denominated loan variable interest rate due September 2029
Debt Instrument [Line Items]
Notes payable and lease obligations		$ 227	$ 225

[1]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2019 related to leases.
[2]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2019 related to leases.
[3]	Redeemed in January 2020

NOTES PAYABLE - Summary of No_2

NOTES PAYABLE - Summary of Notes Payable (Parenthetical) (Detail) $ in Millions, ¥ in Billions	Dec. 31, 2019USD ($)	Dec. 31, 2019JPY (¥)	Sep. 30, 2019JPY (¥)	Apr. 12, 2019JPY (¥)	Dec. 31, 2018JPY (¥)	Oct. 31, 2018USD ($)	Oct. 31, 2018JPY (¥)	Oct. 31, 2017JPY (¥)	Jan. 31, 2017JPY (¥)	Dec. 31, 2016	Sep. 30, 2016USD ($)	Mar. 31, 2015USD ($)	Nov. 30, 2014USD ($)	Jun. 30, 2013USD ($)	Feb. 29, 2012USD ($)	Aug. 31, 2010USD ($)	Dec. 31, 2009USD ($)
4.00% senior notes due February 2022
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%	4.00%			4.00%										4.00%
Debt instrument, principal amount \| $	$ 350														$ 350
3.625% senior notes due June 2023
Debt Instrument [Line Items]
Debt instrument, interest rate	3.625%	3.625%			3.625%									3.625%
Debt instrument, principal amount \| $	$ 700													$ 700
3.625% senior notes due November 2024
Debt Instrument [Line Items]
Debt instrument, interest rate	3.625%	3.625%			3.625%								3.625%
Debt instrument, principal amount \| $	$ 750												$ 750
3.25% senior notes due March 2025
Debt Instrument [Line Items]
Debt instrument, interest rate	3.25%	3.25%			3.25%							3.25%
Debt instrument, principal amount \| $	$ 450											$ 450
2.875% senior notes due October 2026
Debt Instrument [Line Items]
Debt instrument, interest rate	2.875%	2.875%			2.875%						2.875%
Debt instrument, principal amount \| $											$ 300
6.90% senior notes due December 2039
Debt Instrument [Line Items]
Debt instrument, interest rate	6.90%	6.90%			6.90%					6.90%
Debt instrument, principal amount \| $																	$ 400
6.45% senior notes due August 2040
Debt Instrument [Line Items]
Debt instrument, interest rate	6.45%	6.45%			6.45%					6.45%
Debt instrument, principal amount \| $																$ 450
4.00% senior notes due October 2046
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%	4.00%			4.00%						4.00%
Debt instrument, principal amount \| $											$ 400
4.750% senior notes due January 2049
Debt Instrument [Line Items]
Debt instrument, interest rate	4.75%	4.75%			4.75%	4.75%	4.75%
Debt instrument, principal amount \| $						$ 550
.932% senior notes due January 2027
Debt Instrument [Line Items]
Debt instrument, interest rate	0.932%	0.932%			0.932%				0.932%
Debt instrument, principal amount		¥ 60			¥ 60				¥ 60
.500% senior notes due December 2029
Debt Instrument [Line Items]
Debt instrument, interest rate	0.50%	0.50%
Debt instrument, principal amount		¥ 12.6
1.159% senior notes due October 2030
Debt Instrument [Line Items]
Debt instrument, interest rate	1.159%	1.159%			1.159%	1.159%	1.159%
Debt instrument, principal amount		¥ 29.3			¥ 29.3		¥ 29.3
.843% senior notes due December 2031
Debt Instrument [Line Items]
Debt instrument, interest rate	0.843%	0.843%
Debt instrument, principal amount		¥ 9.3
1.488% senior notes due October 2033
Debt Instrument [Line Items]
Debt instrument, interest rate	1.488%	1.488%			1.488%	1.488%	1.488%
Debt instrument, principal amount		¥ 15.2			¥ 15.2		¥ 15.2
.934% senior notes due December 2034
Debt Instrument [Line Items]
Debt instrument, interest rate	0.934%	0.934%
Debt instrument, principal amount		¥ 9.8
1.750% senior notes due October 2038
Debt Instrument [Line Items]
Debt instrument, interest rate	1.75%	1.75%			1.75%	1.75%	1.75%
Debt instrument, principal amount		¥ 8.9			¥ 8.9		¥ 8.9
1.122% senior notes due December 2039
Debt Instrument [Line Items]
Debt instrument, interest rate	1.122%	1.122%
Debt instrument, principal amount		¥ 6.3
2.108% subordinated notes due October 2047
Debt Instrument [Line Items]
Debt instrument, interest rate	2.108%	2.108%			2.108%			2.108%
Debt instrument, principal amount		¥ 60			¥ 60			¥ 60
.963% subordinated bonds due April 2049
Debt Instrument [Line Items]
Debt instrument, interest rate	0.963%	0.963%		0.963%
Debt instrument, principal amount		¥ 30		¥ 30
Yen-denominated loan variable interest rate due September 2026
Debt Instrument [Line Items]
Debt instrument, interest rate	0.42%	0.42%			0.32%
Debt instrument, principal amount		¥ 5	¥ 5		¥ 5
Yen-denominated loan variable interest rate due September 2029
Debt Instrument [Line Items]
Debt instrument, interest rate	0.57%	0.57%			0.47%
Debt instrument, principal amount		¥ 25	¥ 25		¥ 25

NOTES PAYABLE - Aggregate Contr

NOTES PAYABLE - Aggregate Contractual Maturities of Notes Payable (Detail) $ in Millions	Dec. 31, 2019USD ($)
Debt Disclosure [Abstract]
2020	$ 0
2021	0
2022	350
2023	700
2024	750
Thereafter	4,658
Total	$ 6,458

NOTES PAYABLE - Contractual Mat

NOTES PAYABLE - Contractual Maturities of Leases (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Operating Leases
2020		$ 49
2021		37
2022		31
2023		10
2024		10
After 2024		22
Total lease payments		159
Less: Interest		10
Present value of lease liabilities	[1]	149	$ 0
Finance Leases
2020		4
2021		3
2022		2
2023		2
2024		1
After 2024		0
Total lease payments		12
Less: Interest		0
Present value of lease liabilities		12	$ 13
Total
2020		53
2021		40
2022		33
2023		12
2024		11
After 2024		22
Total lease payments		171
Less: Interest		10
Present value of lease liabilities		$ 161

[1]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2019 related to leases.

NOTES PAYABLE - Weighted Averag

NOTES PAYABLE - Weighted Average Lease Term and Discount Rate (Details)	Dec. 31, 2019
Debt Disclosure [Abstract]
Operating lease, weighted average remaining lease term	6 years 9 months 18 days
Finance lease, weighted average remaining lease term	3 years 8 months 12 days
Operating lease, weighted average discount rate, percent	2.10%
Finance lease, weighted average discount rate, percent	1.50%

NOTES PAYABLE - Summary of Line

NOTES PAYABLE - Summary of Lines of Credit (Detail) - 12 months ended Dec. 31, 2019 ¥ in Millions, $ in Millions	USD ($)	JPY (¥)
$100 million line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	The rate quoted by the bank and agreed upon at the time of borrowing
Line of credit facility term	364 days
Line of credit facility, maximum borrowing capacity	$ 100
Line of credit facility, amount outstanding	$ 0
100.0 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	A rate per annum equal to (a) Tokyo interbank market rate (TIBOR) plus, the alternative applicable TIBOR margin during the availability period from the closing date to the commitment termination date or (b) the TIBOR rate offered by the agent to major banks in yen for the applicable period plus, the applicable alternative TIBOR margin during the term out period
Line of credit facility term	5 years
Line of credit facility, maximum borrowing capacity \| ¥		¥ 100,000
Line of credit facility, amount outstanding \| ¥		0
$1.0 billion line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	A rate per annum equal to, at the Company's option, either, (a) the rate for Eurocurrency for deposits in the London interbank market for a period of one, two, three or six months (LIBOR) or (b) a base rate determined by reference to the highest of (1) the federal funds rate plus 1/2 of 1%, (2) the rate of interest in effect for such day as publicly announced from time to time by Mizuho as its “prime rate”, and (3) the LIBOR for a one month interest period in effect on such day (or if such day is not a business day, the immediately preceding business day) plus 1.00%, and in each case an applicable margin
Line of credit facility term	5 years
Line of credit facility, maximum borrowing capacity	$ 1,000
Line of credit facility, amount outstanding	$ 0
$50 million line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	A rate per annum equal to, at the Parent Company's option, either (a) a eurocurrency rate determined by reference to the agent's LIBOR for the interest period relevant to such borrowing or (b) the base rate determined by reference to the greater of (i) the prime rate as determined by the agent, and (ii) the sum of 0.50% and the federal funds rate for such day
Line of credit facility, maximum borrowing capacity	$ 50
Line of credit facility, amount outstanding	$ 0
$250 million line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	USD three-month LIBOR plus 75 basis points per annum
Line of credit facility term	364 days
Line of credit facility, maximum borrowing capacity	$ 250
Line of credit facility, amount outstanding	$ 0
Debt instrument, term	3 months
50.0 billion yen line of credit expiring April 2020
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	Three-month TIBOR plus 70 basis points per annum
Line of credit facility term	364 days
Line of credit facility, maximum borrowing capacity \| ¥		50,000
Line of credit facility, amount outstanding \| ¥		0
Debt instrument, term	3 months
50.0 billion yen line of credit expiring November 2020
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	Three-month TIBOR plus 70 basis points per annum
Line of credit facility term	364 days
Line of credit facility, maximum borrowing capacity \| ¥		50,000
Line of credit facility, amount outstanding \| ¥		¥ 0
Debt instrument, term	3 months
Lower Limit \| 100.0 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.30%
Lower Limit \| $1.0 billion line of credit
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.085%
Upper Limit \| $100 million line of credit
Line of Credit Facility [Line Items]
Debt instrument, term	3 months
Upper Limit \| 100.0 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.50%
Upper Limit \| $1.0 billion line of credit
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.225%
Upper Limit \| $50 million line of credit
Line of Credit Facility [Line Items]
Debt instrument, term	3 months

INCOME TAXES - Additional Infor

INCOME TAXES - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Japan Tax Rate		28.20%	28.00%	28.00%	28.20%
U.S. federal statutory corporate income tax rate	21.00%		21.00%	21.00%	35.00%
Income Tax Expense, Gross, Continuing Operations, Adjustment of Deferred Tax Assets		$ 1,000
Income Tax Benefit, Gross, Continuing Operations, Adjustment of Deferred Tax Liabilities		2,900
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax Asset (Liability)		$ (1,900)		$ 0.4
Deferred Tax Assets, Valuation Allowance			$ 1,340	738
Non-life operating loss carryforwards, limitations			only 35% of non-life operating losses can be offset against life insurance taxable income each year
Operating Loss Carryforwards			$ 99
Unrecognized tax benefit, deductibility highly certain, timing uncertain			15	14
Unrecognized tax benefits, permanent uncertainties			2
Unrecognized tax benefits, interest and penalties expense			1	1	$ 1
Unrecognized tax benefits, accrued interest and penalties			2	$ 2
Anticipatory Foreign Tax Credit
Income Taxes [Line Items]
Deferred Tax Assets, Valuation Allowance			1,022
Deferred Foreign Tax Credit
Income Taxes [Line Items]
Deferred Tax Assets, Valuation Allowance			318
Capital Loss Carryforward
Income Taxes [Line Items]
Tax Credit Carryforward, Amount			161
Expiring in 2039
Income Taxes [Line Items]
Operating Loss Carryforwards			31
No expiration
Income Taxes [Line Items]
Operating Loss Carryforwards			68
Expiring in 2023 \| Capital Loss Carryforward
Income Taxes [Line Items]
Tax Credit Carryforward, Amount			65
Expiring in 2024 \| Capital Loss Carryforward
Income Taxes [Line Items]
Tax Credit Carryforward, Amount			$ 96

INCOME TAXES - Components of In

INCOME TAXES - Components of Income Tax Expense (Benefit) Applicable to Pretax Earnings (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Provision of Income Taxes [Line Items]
Current									$ 806	$ 1,379	$ 631
Deferred									335	(316)	(1,217)
Total income tax expense	$ 276	$ 259	$ 292	$ 314	$ 197	$ 301	$ 299	$ 265	1,141	1,063	(586)
Aflac Japan
Reconciliation of Provision of Income Taxes [Line Items]
Current									737	771	722
Deferred									183	93	(24)
Total income tax expense									920	864	698
Aflac U.S.
Reconciliation of Provision of Income Taxes [Line Items]
Current									69	608	(91)
Deferred									152	(409)	(1,193)
Total income tax expense									$ 221	$ 199	$ (1,284)

INCOME TAXES - Principal Reason

INCOME TAXES - Principal Reasons for Differences and Related Tax Effects where Income Tax Expense Varies from Amount Computed by Applying Expected United States Tax Rate to Pretax Earnings (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income taxes based on U.S. statutory rates									$ 933	$ 836	$ 1,406
Foreign rate differential									229	220	0
Write-down of U.S. deferred tax liabilities for tax reform change									0	0	(1,933)
Utilization of foreign tax credit									(6)	(3)	(27)
Nondeductible expenses									10	21	10
Other, net									(25)	(11)	(42)
Total income tax expense	$ 276	$ 259	$ 292	$ 314	$ 197	$ 301	$ 299	$ 265	$ 1,141	$ 1,063	$ (586)

INCOME TAXES - Total Income Tax

INCOME TAXES - Total Income Tax Expense (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statements of earnings	$ 276	$ 259	$ 292	$ 314	$ 197	$ 301	$ 299	$ 265	$ 1,141	$ 1,063	$ (586)
Other comprehensive income (loss):
Unrealized foreign currency translation gains (losses) during period									27	10	52
Unrealized gains (losses) on investment securities:
Unrealized holding gains (losses) on investment securities during period									1,532	(787)	575
Reclassification adjustment for realized (gains) losses on investment securities included in net earnings									5	(12)	1
Unrealized gains (losses) on derivatives during period									(3)	0	0
Pension liability adjustment during period									(18)	(8)	3
Total income tax expense (benefit) related to items of other comprehensive income (loss)									1,543	(797)	631
Total income taxes									$ 2,684	$ 266	$ 45

INCOME TAXES - Income Tax Effec

INCOME TAXES - Income Tax Effects of Temporary Differences that Gave Rise to Deferred Income Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred income tax liabilities:
Deferred policy acquisition costs	$ 3,492	$ 3,404
Unrealized gains and other basis differences on investments	4,485	1,307
Premiums receivable	152	149
Policy benefit reserves	3,442	3,828
Total deferred income tax liabilities	11,571	8,688
Deferred income tax assets:
Unfunded retirement benefits	8	8
Other accrued expenses	36	40
Policy and contract claims	781	775
Foreign currency loss on Aflac Japan	16	38
Deferred compensation	162	163
Capital loss carryforwards	34	5
Depreciation	164	119
Anticipatory foreign tax credit	5,487	4,040
Deferred foreign tax credit	605	591
Other	204	150
Total deferred income tax assets before valuation allowance	7,497	5,929
Valuation allowance	(1,340)	(738)
Total deferred income tax assets after valuation allowance	6,157	5,191
Net deferred income tax liability	5,414	3,497
Current income tax asset	(44)
Current income tax liability		523
Total income tax liability	$ 5,370	$ 4,020

INCOME TAXES - Reconciliation o

INCOME TAXES - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, beginning of year	$ 15	$ 14
Additions for tax positions of prior years	2	1
Balance, end of year	$ 17	$ 15

SHAREHOLDERS' EQUITY - Addition

SHAREHOLDERS' EQUITY - Additional Information (Detail) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)Voteshares	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)shares
Stockholders Equity Note [Line Items]
Common stock, share repurchase, dollar amount \| $	$ 1,627	$ 1,301	$ 1,351
Remaining common stock available for purchase under share repurchase authorizations \| shares	37.1
Common stock, voting rights	are generally entitled to one vote per share until they have been held by the same beneficial owner for a continuous period of 48 months, at which time they become entitled to 10 votes per share.
Share Held For Less Than A Continuous Forty Eight Month Period
Stockholders Equity Note [Line Items]
Common stock, votes per share \| Vote	1
Share Held For Continuous Forty Eight Month Period
Stockholders Equity Note [Line Items]
Common stock, votes per share \| Vote	10
Share Repurchase Program
Stockholders Equity Note [Line Items]
Stock acquired under share repurchase program, shares \| shares	32	28.9	35.5
Common stock, share repurchase, dollar amount \| $	$ 1,600	$ 1,300	$ 1,400

SHAREHOLDERS' EQUITY - Reconcil

SHAREHOLDERS' EQUITY - Reconciliation of Number of Shares of Common Stock (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock Issued [Roll Forward]
Balance, beginning of period	1,347,540	1,345,762	1,342,498
Exercise of stock options and issuance of restricted shares	1,769	1,778	3,264
Balance, end of period	1,349,309	1,347,540	1,345,762
Treasury Stock [Roll Forward]
Balance, beginning of period	592,254	564,852	530,877
Exercise of stock options	(1,584)	(1,874)	(5,766)
Balance, end of period	622,516	592,254	564,852
Shares outstanding, end of period	726,793	755,286	780,910
Treasury Stock
Treasury Stock [Roll Forward]
Stock acquired under share repurchase program, shares	31,994	28,949	35,510
Other purchases	592	392	1,018
Shares issued to AFL Stock Plan	(1,610)	(1,306)	(1,782)
Exercise of stock options	(418)	(519)	(734)
Other dispositions	(296)	(114)	(37)

SHAREHOLDERS' EQUITY - Anti-Dil

SHAREHOLDERS' EQUITY - Anti-Dilutive Share-Based Awards Excluded from Calculation of Diluted Earnings Per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Anti-dilutive share-based awards	6	44	510

SHAREHOLDERS' EQUITY - Weighted

SHAREHOLDERS' EQUITY - Weighted-Average Shares Used in Calculating Earnings Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Weighted-average outstanding shares used for calculating basic EPS	742,414	769,588	792,042
Dilutive effect of share-based awards	4,016	5,062	5,819
Weighted-average outstanding shares used for calculating diluted EPS	746,430	774,650	797,861

SHAREHOLDERS' EQUITY - Changes

SHAREHOLDERS' EQUITY - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	$ 2,151	$ 4,028	$ 2,630
Other comprehensive income loss before reclassifications net of tax	4,466	(2,150)	1,386
Amounts reclassified from accumulated other comprehensive income net of tax	(2)	47	12
Other comprehensive income (loss), net of tax	4,464	(2,103)	1,398
Balance, end of period	6,615	2,151	4,028
Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		(148)
Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		374
Unrealized foreign currency translation gains (losses)
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(1,847)	(1,750)	(1,983)
Other comprehensive income loss before reclassifications net of tax	224	228	233
Amounts reclassified from accumulated other comprehensive income net of tax	0	0	0
Other comprehensive income (loss), net of tax	224	228	233
Balance, end of period	(1,623)	(1,847)	(1,750)
Unrealized foreign currency translation gains (losses) \| Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		0
Unrealized foreign currency translation gains (losses) \| Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		(325)
Unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	4,234	5,964	4,805
Other comprehensive income loss before reclassifications net of tax	4,327	(2,350)	1,158
Amounts reclassified from accumulated other comprehensive income net of tax	(13)	34	1
Other comprehensive income (loss), net of tax	4,314	(2,316)	1,159
Balance, end of period	8,548	4,234	5,964
Unrealized gains (losses) on investment securities \| Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		(148)
Unrealized gains (losses) on investment securities \| Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		734
Unrealized gains (losses) on derivatives
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(24)	(23)	(24)
Other comprehensive income loss before reclassifications net of tax	(9)	2	1
Amounts reclassified from accumulated other comprehensive income net of tax	0	0	0
Other comprehensive income (loss), net of tax	(9)	2	1
Balance, end of period	(33)	(24)	(23)
Unrealized gains (losses) on derivatives \| Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		0
Unrealized gains (losses) on derivatives \| Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		(3)
Pension liability adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(212)	(163)	(168)
Other comprehensive income loss before reclassifications net of tax	(76)	(30)	(6)
Amounts reclassified from accumulated other comprehensive income net of tax	11	13	11
Other comprehensive income (loss), net of tax	(65)	(17)	5
Balance, end of period	$ (277)	(212)	$ (163)
Pension liability adjustment \| Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		0
Pension liability adjustment \| Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax		$ (32)

SHAREHOLDERS' EQUITY - Reclassi

SHAREHOLDERS' EQUITY - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended								12 Months Ended
		Jan. 31, 2018	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other gains (losses)											$ (104)		$ (349)		$ (114)
Total before tax			$ 1,058	$ 1,036	$ 1,109	$ 1,242	$ 722	$ 1,146	$ 1,131	$ 982	4,445		3,983		4,018
Income tax (expense) benefit			$ (276)	$ (259)	$ (292)	$ (314)	$ (197)	$ (301)	$ (299)	$ (265)	(1,141)		(1,063)		586
Net of tax											$ 3,304		$ 2,920		$ 4,604
Blended statutory income tax rate											26.00%		27.00%
U.S. federal statutory corporate income tax rate		21.00%									21.00%		21.00%		35.00%
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax											$ 2		$ (47)		$ (12)
Reclassification out of Accumulated Other Comprehensive Income \| Unrealized gains (losses) on investment securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment losses realized											(13)		(63)
Other-than-temporary impairment losses realized															(29)
Other gains (losses)											31		17		27
Total before tax											18		(46)		(2)
Income tax (expense) benefit											(5)	[1]	12	[2]	1	[3]
Net of tax											13		(34)		(1)
Reclassification out of Accumulated Other Comprehensive Income \| Pension liability adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Acquisition and operating expense, actuarial gains (losses)	[4]										(15)		(18)		(17)
Acquisition and operating expenses, prior service (cost) credit	[4]										0		0		0
Income tax (expense) benefit											4	[1]	5	[2]	6	[3]
Net of tax											$ (11)		$ (13)		$ (11)

[1]	Based on 26% blended tax rate
[2]	Based on 27% blended tax rate
[3]	Based on 35% tax rate
[4]	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 14 for additional details).

SHARE-BASED COMPENSATION - Addi

SHARE-BASED COMPENSATION - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	1 Months Ended		12 Months Ended
	Nov. 30, 2019	Feb. 28, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation arrangement by share-based payment award, options, grants in period, weighted average grant date fair value			$ 0	$ 8.81	$ 7.64
Closing common stock price			$ 52.90
Aggregate intrinsic value of stock options outstanding			$ 86
Options outstanding - weighted-average remaining term (Yrs)			4 years 4 months 24 days
In-the-money stock options exercisable			3,600
Aggregate intrinsic value of stock options exercisable			$ 84
Weighted-average remaining term of stock options exercisable (in years)			4 years 2 months 12 days
Long-Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, maximum number of shares issuable			75,000
Share-based compensation arrangement by share-based payment award, maximum number of shares issuable other than options and stock appreciation rights			38,000
Shares available for future grants under the long-term incentive plan			39,300
Long-term incentive plan awards, term (in years)			10 years
Long-term incentive plan, vesting period			3 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards, grants in period			1,070	1,121	1,118
Total compensation cost not yet recognized, restricted stock awards			$ 60
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number of shares			2,573	3,407	3,634	3,736
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition			1 year 1 month 6 days
Performance Based Vesting Condition \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term incentive plan, vesting period			3 years
Restricted stock awards, grants in period		399
Percentage of target award opportunities minimum			0.00%
Percentage of target award opportunities maximum			200.00%
Total compensation cost not yet recognized, restricted stock awards			$ 30
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number of shares			1,500
Performance Based Vesting Condition \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term incentive plan, vesting period			3 years
Restricted stock awards, grants in period	46
Percentage of target award opportunities minimum			0.00%
Percentage of target award opportunities maximum			200.00%

SHARE-BASED COMPENSATION - Expe

SHARE-BASED COMPENSATION - Expense Recognized in Connection with Share-Based Awards (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Earnings before income taxes	$ 1,058	$ 1,036	$ 1,109	$ 1,242	$ 722	$ 1,146	$ 1,131	$ 982	$ 4,445	$ 3,983	$ 4,018
Net earnings									$ 3,304	$ 2,920	$ 4,604
Net earnings per share:
Basic (in dollars per share)	$ 1.07	$ 1.05	$ 1.10	$ 1.23	$ 0.69	$ 1.10	$ 1.08	$ 0.92	$ 4.45	$ 3.79	$ 5.81
Diluted (in dollars per share)	$ 1.06	$ 1.04	$ 1.09	$ 1.23	$ 0.69	$ 1.09	$ 1.07	$ 0.91	$ 4.43	$ 3.77	$ 5.77
Share Based Compensation Expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Earnings from continuing operations									$ 59	$ 57	$ 51
Earnings before income taxes									59	57	51
Net earnings									$ 46	$ 45	$ 35
Net earnings per share:
Basic (in dollars per share)									$ 0.06	$ 0.06	$ 0.05
Diluted (in dollars per share)									$ 0.06	$ 0.06	$ 0.05

SHARE-BASED COMPENSATION - Stoc

SHARE-BASED COMPENSATION - Stock Option Activity (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Option Shares
Beginning Balance	5,330	7,304	12,680
Granted	0	67	626
Canceled	(40)	(167)	(236)
Exercised	(1,584)	(1,874)	(5,766)
Ending Balance	3,706	5,330	7,304
Weighted-Average Exercise Price Per Share
Beginning Balance	$ 28.54	$ 28.03	$ 26.28
Granted	0	44.59	35.80
Canceled	27.82	32.11	24.95
Exercised	25.97	26.78	30.11
Ending Balance	$ 29.65	$ 28.54	$ 28.03

SHARE-BASED COMPENSATION - Shar

SHARE-BASED COMPENSATION - Shares Exercisable (Detail) - shares shares in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Shares exercisable, end of year	3,553	3,917	4,208

SHARE-BASED COMPENSATION - Assu

SHARE-BASED COMPENSATION - Assumptions Used in Valuing Options Granted (Detail) - Employee stock option	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Line Items]
Expected term (years)	7 years	7 years	5 years 10 months 24 days
Expected volatility	18.00%	22.00%	26.00%
Annual forfeiture rate	3.90%	3.60%	3.40%
Risk-free interest rate	2.90%	2.50%	2.50%
Dividend yield	2.20%	2.40%	2.50%

SHARE-BASED COMPENSATION - St_2

SHARE-BASED COMPENSATION - Stock Options Outstanding and Exercisable (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	$ 16.92
Range of Exercise Prices Per Share - Upper Range	$ 44.59
Options Outstanding - Stock Option Shares	3,706	5,330	7,304	12,680
Options outstanding - weighted-average remaining term (Yrs)	4 years 4 months 24 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 29.65	$ 28.54	$ 28.03	$ 26.28
Options Exercisable - Stock Option Shares	3,553	3,917	4,208
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 29.40
$16.92 - $24.75
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	16.92
Range of Exercise Prices Per Share - Upper Range	$ 24.75
Options Outstanding - Stock Option Shares	872
Options outstanding - weighted-average remaining term (Yrs)	2 years 1 month 6 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 23.58
Options Exercisable - Stock Option Shares	872
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 23.58
$24.79 - $28.97
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	24.79
Range of Exercise Prices Per Share - Upper Range	$ 28.97
Options Outstanding - Stock Option Shares	919
Options outstanding - weighted-average remaining term (Yrs)	3 years 9 months 18 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 28.49
Options Exercisable - Stock Option Shares	919
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 28.49
$29.04 - $31.21
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	29.04
Range of Exercise Prices Per Share - Upper Range	$ 31.21
Options Outstanding - Stock Option Shares	988
Options outstanding - weighted-average remaining term (Yrs)	4 years 8 months 12 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 30.77
Options Exercisable - Stock Option Shares	988
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 30.77
$31.22 - $36.21
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	31.22
Range of Exercise Prices Per Share - Upper Range	$ 36.21
Options Outstanding - Stock Option Shares	778
Options outstanding - weighted-average remaining term (Yrs)	6 years 6 months
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 34.31
Options Exercisable - Stock Option Shares	626
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 34.02
$37.22 - $44.59
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	37.22
Range of Exercise Prices Per Share - Upper Range	$ 44.59
Options Outstanding - Stock Option Shares	149
Options outstanding - weighted-average remaining term (Yrs)	7 years 9 months 18 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 40.57
Options Exercisable - Stock Option Shares	148
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 40.59

SHARE-BASED COMPENSATION - Summ

SHARE-BASED COMPENSATION - Summary of Stock Option Activity (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Total intrinsic value of options exercised	$ 38	$ 34	$ 87
Cash received from options exercised	40	48	58
Tax benefit realized as a result of options exercised and restricted stock releases	$ 34	$ 25	$ 74

SHARE-BASED COMPENSATION - Key

SHARE-BASED COMPENSATION - Key Assumptions Used to Value PBRS (Details) - Performance Based Vesting Condition - Restricted Stock	12 Months Ended
	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (based on Aflac Inc. and peer group historical daily stock price)	15.82%
Expected life from grant date (years)	2 years 10 months 24 days
Risk-free interest rate (based on U.S. Treasury yields at the date of grant)	2.51%

SHARE-BASED COMPENSATION - Rest

SHARE-BASED COMPENSATION - Restricted Stock Activity (Detail) - Restricted Stock - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Beginning balance	3,407	3,634	3,736
Granted	1,070	1,121	1,118
Canceled	(39)	(105)	(202)
Vested	(1,865)	(1,243)	(1,018)
Ending Balance	2,573	3,407	3,634
Weighted-Average Grant-Date Fair Value Per Share
Beginning balance	$ 36.52	$ 32.40	$ 30.88
Granted	49.68	44.27	36.48
Canceled	41.60	34.39	32.23
Vested	32.73	31.64	31.09
Ending Balance	$ 44.66	$ 36.52	$ 32.40

STATUTORY ACCOUNTING AND DIVI_3

STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statutory Accounting Practices [Line Items]
Statutory accounting practices, statutory capital and surplus required	$ 400
Aflac
Statutory Accounting Practices [Line Items]
Capital and surplus, statutory accounting practices of the state or country basis	2,100	$ 2,600
Net Income, Nebraska state basis	864	1,300	$ 2,600
Capital and surplus, NAIC basis	2,100	2,600
Amount available for dividend distribution without prior approval from regulatory agency	864
Dividends declared	1,300
Aflac Japan
Statutory Accounting Practices [Line Items]
Capital and surplus, statutory accounting practices of the state or country basis	$ 7,800	$ 6,400

STATUTORY ACCOUNTING AND DIVI_4

STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS - Profit Remittances by Aflac Japan (Detail) $ in Millions, ¥ in Billions	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2019JPY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2018JPY (¥)	Dec. 31, 2017USD ($)	Dec. 31, 2017JPY (¥)
Insurance [Abstract]
Profit remittances	$ 2,070	¥ 225.2	$ 808	¥ 89.7	$ 1,150	¥ 129.3

BENEFIT PLANS - Additional Info

BENEFIT PLANS - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amount of years active employees have left to meet rule of 80 in order to be eligible for postretirement medical benefits				5 years
Amount of years left to meet 15 year service requirement for active employees age 55 or older to be eligible for postretirement medical benefits				5 years
Net periodic (benefit) cost, excluding service cost	$ 8	$ 25	$ 35
Transition obligation	$ 0
Percentage of matching contributions by the Company to employee's contributions to 401(k) plan	100.00%
Non-elective defined contribution percentage of employee compensation	2.00%
Matching 401(k) plan contributions included in acquisition and operating expenses	$ 18	18	15
Shares of employer-issued common stock held for plan participants by plan trustee (in millions)	2.6
Lower Limit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Health care plan, retirement age and years of service combined years for eligibility (rule of 80)				80 years
Health care plan, retirement age for eligibility, (in years)				55 years
Health care plan, number of years of service for eligibility				15 years
Upper Limit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of matching contributions by the Company to employee's contributions to 401(k) plan	4.00%
Associate Stock Bonus Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred policy acquisition costs, amount attributable to stock bonus plan	$ 31	31	31
Foreign Plan \| Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, expected contributions to the plan in the following year	$ 35
Japan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
AA corporate bonds average duration	20 years
Japan \| Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, plan assets, amount	$ 344	289	270
U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
AA corporate bonds average duration	17 years
U.S. \| Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, expected contributions to the plan in the following year	$ 0
Defined benefit plan, plan assets, amount	644	465	$ 448
Level 1 \| U.S. \| Pension Plan \| Cash and cash equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, plan assets, amount	$ 100	$ 39

BENEFIT PLANS - Reconciliation

BENEFIT PLANS - Reconciliation of Funded Status of Basic Employee Defined-Benefit Pension Plans (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Other Postretirement Benefit Plans, Defined Benefit
Projected benefit obligation:
Benefit obligation, beginning of year		$ 37		$ 36
Service cost		0		0	$ 0
Interest cost		1		1	1
Actuarial (gain) loss		4		4
Benefits and expenses paid		(3)		(4)
Effect of foreign exchange rate changes		0		0
Benefit obligation, end of year		39		37	36
Plan assets:
Fair value of plan assets, beginning of year		0		0
Actual return on plan assets		0		0
Employer contributions		3		4
Benefits and expenses paid		(3)		(4)
Effect of foreign exchange rate changes		0		0
Fair value of plan assets, end of year		0		0	0
Funded status of the plans	[1]	(39)		(37)
Amounts recognized in accumulated other comprehensive income:
Net actuarial (gain) loss		12		9
Prior service (credit) cost		0		0
Total included in accumulated other comprehensive income		12		9
Japan \| Pension Plan
Projected benefit obligation:
Benefit obligation, beginning of year		396		341
Service cost		22		19	20
Interest cost		7		7	6
Actuarial (gain) loss		17		35
Benefits and expenses paid		(11)		(11)
Effect of foreign exchange rate changes		5		5
Benefit obligation, end of year		436		396	341
Plan assets:
Fair value of plan assets, beginning of year		289		270
Actual return on plan assets		24		(9)
Employer contributions		38		34
Benefits and expenses paid		(11)		(11)
Effect of foreign exchange rate changes		4		5
Fair value of plan assets, end of year		344		289	270
Funded status of the plans	[1]	(92)		(107)
Amounts recognized in accumulated other comprehensive income:
Net actuarial (gain) loss		92		95
Prior service (credit) cost		(2)		(2)
Total included in accumulated other comprehensive income		90		93
Accumulated benefit obligation		390		356
U.S. \| Pension Plan
Projected benefit obligation:
Benefit obligation, beginning of year		875		908
Service cost		23		27	24
Interest cost		20		31	40
Actuarial (gain) loss		163	[2]	(69)
Benefits and expenses paid		(23)		(22)
Effect of foreign exchange rate changes		0		0
Benefit obligation, end of year		1,058		875	908
Plan assets:
Fair value of plan assets, beginning of year		465		448
Actual return on plan assets		98		(30)
Employer contributions		104		69
Benefits and expenses paid		(23)		(22)
Effect of foreign exchange rate changes		0		0
Fair value of plan assets, end of year		644		465	$ 448
Funded status of the plans	[1]	(414)		(410)
Amounts recognized in accumulated other comprehensive income:
Net actuarial (gain) loss		259		174
Prior service (credit) cost		(4)		(4)
Total included in accumulated other comprehensive income		255		170
Accumulated benefit obligation		886		746
U.S. \| Pension Plan \| Funded Plan
Plan assets:
Employer contributions		$ 95		$ 60

[1]	Recognized in other liabilities in the consolidated balance sheets
[2]	Actuarial losses increased due to lower discount rates at the end of 2019. Also, additional funds were contributed to the U.S. funded defined benefit plan in 2019. The Company contributed $95 million in 2019 compared to $60 million in 2018.

BENEFIT PLANS - Information for

BENEFIT PLANS - Information for Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets (Details) - Pension Plan - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Japan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 390	$ 356
Fair value of plan assets	344	289
U.S.
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	886	746
Fair value of plan assets	$ 644	$ 465

BENEFIT PLANS - Information f_2

BENEFIT PLANS - Information for Pension Plans with a Projected Benefit Obligation in Excess of Plan Assets (Details) - Pension Plan - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Japan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	[1]	$ 436	$ 396
Fair value of plan assets	[1]	344	289
Funded status of the plans	[2]	(92)	(107)
U.S.
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	[3]	1,058	875
Fair value of plan assets	[3]	644	465
Funded status of the plans	[2]	$ (414)	$ (410)

[1]	The net amount of projected benefit obligation and plan assets for the underfunded (including unfunded) Japan pension plan was $92 and $107 at December 31, 2019 and 2018, respectively, and was classified as liabilities on the statement of financial position.
[2]	Recognized in other liabilities in the consolidated balance sheets
[3]	The net amount of projected benefit obligation and plan assets for the underfunded (including unfunded) U.S. pension plan was $414 and $410 at December 31, 2019 and 2018, respectively, and was classified as liabilities on the statement of financial position.

BENEFIT PLANS - Weighted-Averag

BENEFIT PLANS - Weighted-Average Actuarial Assumptions (Detail)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Postretirement Benefit Plans, Defined Benefit
Weighted-average actuarial assumptions:
Discount rate - net periodic benefit cost		4.25%	3.75%	4.25%
Discount rate - benefit obligations		3.25%	4.25%	3.75%
Health care cost trend rates	[1]	7.50%	7.40%	5.40%
Defined benefit plan, ultimate health care cost trend rate		3.80%	4.10%	4.50%
Defined benefit plan number of years that rate reaches ultimate trend rate		54 years	61 years	77 years
Japan \| Pension Plan
Weighted-average actuarial assumptions:
Discount rate - net periodic benefit cost		1.25%	1.25%	1.25%
Discount rate - benefit obligations		0.75%	1.25%	1.25%
Expected long-term return on plan assets		2.00%	2.00%	2.00%
U.S. \| Pension Plan
Weighted-average actuarial assumptions:
Discount rate - net periodic benefit cost		4.25%	3.75%	4.25%
Discount rate - benefit obligations		3.25%	4.25%	3.75%
Expected long-term return on plan assets		6.25%	6.50%	6.75%
Rate of compensation increase		4.00%	4.00%	4.00%

[1]	For the years 2019 , 2018 and 2017 , the health care cost trend rates are expected to trend down to 3.8% in 54 years , 4.1% in 61 years , and 4.5% in 77 years , respectively.

BENEFIT PLANS - Net Periodic (B

BENEFIT PLANS - Net Periodic (Benefit) Cost Included in Acquisition and Operating Expenses (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 0	$ 0	$ 0
Interest cost	1	1	1
Expected return on plan assets	0	0	0
Amortization of net actuarial loss	1	1	1
Net periodic (benefit) cost	2	2	2
Japan \| Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	22	19	20
Interest cost	7	7	6
Expected return on plan assets	(6)	(6)	(5)
Amortization of net actuarial loss	4	1	2
Net periodic (benefit) cost	27	21	23
U.S. \| Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	23	27	24
Interest cost	20	31	40
Expected return on plan assets	(29)	(26)	(24)
Amortization of net actuarial loss	10	16	14
Net periodic (benefit) cost	$ 24	$ 48	$ 54

BENEFIT PLANS - Summary of Amou

BENEFIT PLANS - Summary of Amounts Recognized in Other Comprehensive Loss (Income) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	$ 4	$ 4	$ 0
Amortization of net actuarial loss	(1)	(1)	(1)
Total	3	3	(1)
Japan \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	1	52	(21)
Amortization of net actuarial loss	(4)	(1)	(2)
Total	(3)	51	(23)
U.S. \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	95	(13)	28
Amortization of net actuarial loss	(10)	(16)	(14)
Total	$ 85	$ (29)	$ 14

BENEFIT PLANS - Expected Benefi

BENEFIT PLANS - Expected Benefit Payments (Detail) $ in Millions	Dec. 31, 2019USD ($)
Other Postretirement Benefit Plans, Defined Benefit
Schedule of Postemployment Expected Future Benefit Payments [Line Items]
2020	$ 3
2021	4
2022	4
2023	4
2024	4
2025-2029	16
Japan \| Pension Plan
Schedule of Postemployment Expected Future Benefit Payments [Line Items]
2020	13
2021	12
2022	17
2023	14
2024	16
2025-2029	84
U.S. \| Pension Plan
Schedule of Postemployment Expected Future Benefit Payments [Line Items]
2020	25
2021	27
2022	29
2023	30
2024	31
2025-2029	$ 203

BENEFIT PLANS - Asset Allocatio

BENEFIT PLANS - Asset Allocation Targets (Detail) - Pension Plan	Dec. 31, 2019
Japan
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	100.00%
U.S.
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	100.00%
Domestic equity securities \| Japan
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	5.00%
Domestic equity securities \| U.S.
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	40.00%
International equity securities \| Japan
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	20.00%
International equity securities \| U.S.
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	20.00%
Fixed income bond funds \| Japan
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	66.00%
Fixed income bond funds \| U.S.
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	40.00%
Other Investments \| Japan
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	9.00%
Other Investments \| U.S.
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	0.00%

BENEFIT PLANS - Fair Value Hier

BENEFIT PLANS - Fair Value Hierarchy Levels of Funded Pension Plans' Assets (Detail) - Pension Plan - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Japan
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 344	$ 289	$ 270
U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	644	465	$ 448
Japanese equity securities \| Japan \| Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	17	14
International equity securities \| Japan \| Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	67	50
Japanese bonds \| Japan \| Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	20	34
International bonds \| Japan \| Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	207	160
Insurance contracts \| Japan \| Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	33	31
U.S. large cap equity securities \| U.S. \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	179	120
U.S. mid cap equity securities \| U.S. \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	22	17
Real estate equity funds \| U.S. \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	16	13
International equity funds \| U.S. \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	112	92
Fixed income bond funds \| U.S. \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	209	179
Aflac Incorporated common stock \| U.S. \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	6	5
Cash and cash equivalents \| U.S. \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 100	$ 39

COMMITMENTS AND CONTINGENT LI_2

COMMITMENTS AND CONTINGENT LIABILITIES - Additional Information (Detail) $ in Millions, ¥ in Billions	3 Months Ended	12 Months Ended
	Mar. 31, 2017USD ($)	Dec. 31, 2019USD ($)agreements	Dec. 31, 2019JPY (¥)agreements
Commitments and Contingencies Disclosure [Line Items]
Number of operating service agreements, technology and consulting \| agreements		2	2
Number of operating service agreements, management consulting and technology \| agreements		1	1
Number of operating service agreements, information technology and data services \| agreements		2	2
Loss contingency accrual, insurance-related assessment, discount rate	4.25%
Loss contingency, discounted amount of insurance-related assessment liability	$ 62
Loss contingency, undiscounted amount of insurance-related assessment liability	94
Loss contingency, insurance related assessment, discounted amount of premium tax offset	48
Loss contingency, insurance-related assessment, undiscounted amount of premium tax offset	74
Loss contingency, loss in period	$ 14
Mainframe and server computer operations and support
Commitments and Contingencies Disclosure [Line Items]
Outsourcing agreements, remaining term		3 years	3 years
Outsourcing agreements, aggregate remaining cost		$ 244	¥ 26.7
Technology and consulting company application maintenance and development services
Commitments and Contingencies Disclosure [Line Items]
Outsourcing agreements, remaining term		4 years	4 years
Outsourcing agreements, aggregate remaining cost		$ 61	¥ 6.6
Management consulting and technology services company application maintenance and development services
Commitments and Contingencies Disclosure [Line Items]
Outsourcing agreements, remaining term		2 years	2 years
Outsourcing agreements, aggregate remaining cost		$ 63	¥ 6.9
Information technology and data services company application maintenance and development services first agreement
Commitments and Contingencies Disclosure [Line Items]
Outsourcing agreements, remaining term		3 years	3 years
Outsourcing agreements, aggregate remaining cost		$ 50	¥ 5.5
Information technology and data services company application maintenance and development services second agreement
Commitments and Contingencies Disclosure [Line Items]
Outsourcing agreements, remaining term		3 years	3 years
Outsourcing agreements, aggregate remaining cost		$ 45	¥ 4.9

SUBSEQUENT EVENTS - Additional

SUBSEQUENT EVENTS - Additional Information (Detail) - 4.00% senior notes due February 2022 - USD ($) $ in Millions		1 Months Ended
		Jan. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 29, 2012
Subsequent Event [Line Items]
Debt instrument, interest rate			4.00%	4.00%	4.00%
Subsequent Event
Subsequent Event [Line Items]
Repayments of debt	[1]	$ 350
Debt instrument, interest rate		4.00%

[1]	Redeemed in January 2020

Unaudited Consolidated Quarte_3

Unaudited Consolidated Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, [Line Items]
Net premium income	$ 4,671	$ 4,736	$ 4,681	$ 4,691	$ 4,591	$ 4,636	$ 4,706	$ 4,745	$ 18,780	$ 18,677	$ 18,531
Net investment income	886	936	878	878	874	870	862	837	3,578	3,442	3,220
Realized investment gains (losses)	12	(153)	(66)	71	(355)	56	3	(134)
Other income (loss)	34	17	18	17	16	15	18	16	84	69	67
Total revenues	5,603	5,536	5,511	5,657	5,126	5,577	5,589	5,464	22,307	21,758	21,667
Total benefits and expenses	4,545	4,500	4,402	4,415	4,404	4,431	4,458	4,482	17,862	17,775	17,649
Earnings before income taxes	1,058	1,036	1,109	1,242	722	1,146	1,131	982	4,445	3,983	4,018
Total income tax expense	276	259	292	314	197	301	299	265	$ 1,141	$ 1,063	$ (586)
Net earnings	$ 782	$ 777	$ 817	$ 928	$ 525	$ 845	$ 832	$ 717
Net earnings per basic share	$ 1.07	$ 1.05	$ 1.10	$ 1.23	$ 0.69	$ 1.10	$ 1.08	$ 0.92	$ 4.45	$ 3.79	$ 5.81
Net earnings per diluted share	$ 1.06	$ 1.04	$ 1.09	$ 1.23	$ 0.69	$ 1.09	$ 1.07	$ 0.91	$ 4.43	$ 3.77	$ 5.77
Parent Company
Condensed Income Statements, [Line Items]
Net investment income									$ 77	$ 69	$ 30
Total revenues									330	247	331
Total income tax expense									$ (22)	$ (12)	$ (23)

Schedule II - Aflac Incorporate

Schedule II - Aflac Incorporated (Parent Only) - Condensed Statement of Earnings (Detail) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, [Line Items]
Net investment income		$ 886	$ 936	$ 878	$ 878	$ 874	$ 870	$ 862	$ 837	$ 3,578	$ 3,442	$ 3,220
Realized investment gains (losses)										(135)	(430)	(151)
Total revenues		5,603	5,536	5,511	5,657	5,126	5,577	5,589	5,464	22,307	21,758	21,667
Interest expense										228	222	240
Income tax expense (benefit)		$ 276	$ 259	$ 292	$ 314	$ 197	$ 301	$ 299	$ 265	1,141	1,063	(586)
Net earnings										3,304	2,920	4,604
Parent Company
Condensed Income Statements, [Line Items]
Management and service fees from subsidiaries	[1]									151	190	297
Net investment income										77	69	30
Interest from subsidiaries	[1]									4	4	5
Realized investment gains (losses)										98	(16)	(1)
Total revenues										330	247	331
Interest expense										200	188	197
Other operating expenses										221	225	180	[2]
Total operating expenses										421	413	377
Earnings before income taxes and equity in earnings of subsidiaries										(91)	(166)	(46)
Income tax expense (benefit)										(22)	(12)	(23)
Earnings before equity in earnings of subsidiaries										(69)	(154)	(23)
Equity in earnings of subsidiaries	[1]									3,373	3,074	4,627
Net earnings										$ 3,304	$ 2,920	4,604
5.50% subordinated notes due September 2052
Condensed Income Statements, [Line Items]
Expense on extinguishment of debt												$ 13

[1]	Eliminated in consolidation
[2]	Includes expense of $13 in 2017 for the early extinguishment of debt

Schedule II - Aflac Incorpora_2

Schedule II - Aflac Incorporated (Parent Only) - Condensed Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net earnings	$ 3,304	$ 2,920	$ 4,604
Other comprehensive income (loss) before income taxes:
Unrealized foreign currency translation gains (losses) during period	252	232	286
Unrealized gains (losses) on derivatives during period	(12)	2	1
Pension liability adjustment during period	(85)	(25)	9
Total other comprehensive income (loss) before income taxes	6,007	(2,900)	2,029
Income tax expense (benefit) related to items of other comprehensive income (loss)	1,543	(797)	631
Other comprehensive income (loss), net of tax	4,464	(2,103)	1,398
Total comprehensive income (loss)	7,768	817	6,002
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net earnings	3,304	2,920	4,604
Other comprehensive income (loss) before income taxes:
Unrealized foreign currency translation gains (losses) during period	252	232	286
Unrealized gains (losses) on fixed maturity securities during period	5,852	(3,109)	1,733
Unrealized gains (losses) on derivatives during period	(12)	2	1
Pension liability adjustment during period	(85)	(25)	9
Total other comprehensive income (loss) before income taxes	6,007	(2,900)	2,029
Income tax expense (benefit) related to items of other comprehensive income (loss)	1,543	(797)	631
Other comprehensive income (loss), net of tax	4,464	(2,103)	1,398
Total comprehensive income (loss)	$ 7,768	$ 817	$ 6,002

Schedule II - Aflac Incorpora_3

Schedule II - Aflac Incorporated (Parent Only) - Condensed Balance Sheet (Detail 1) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments and cash:
Fixed maturity securities available for sale, at fair value (amortized cost $1,506 in 2019 and $1,209 in 2018)		$ 91,262	$ 82,895
Other investments		1,477	787
Cash and cash equivalents		4,896	4,337	$ 3,491	$ 4,859
Total investments and cash		138,091	126,243
Other assets		2,368	2,221
Total assets		152,768	140,406
Liabilities:
Notes payable		6,408	5,765
Other liabilities		3,440	2,906
Total liabilities		123,809	116,944
Shareholders' equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2019 and 2018; issued 1,349,309 shares in 2019 and 1,347,540 shares in 2018		135	135
Additional paid-in capital		2,313	2,177
Retained earnings		34,291	31,788
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains (losses)		(1,623)	(1,847)
Unrealized gains (losses) on fixed maturity securities		8,548	4,234
Unrealized gains (losses) on derivatives		(33)	(24)
Pension liability adjustment		(277)	(212)
Treasury stock, at average cost		(14,395)	(12,789)
Total shareholders' equity		28,959	23,462	24,598	20,482
Total liabilities and shareholders' equity		152,768	140,406
Parent Company
Investments and cash:
Fixed maturity securities available for sale, at fair value (amortized cost $1,506 in 2019 and $1,209 in 2018)		1,567	1,222
Investments in subsidiaries	[1]	30,744	26,230
Other investments		36	21
Cash and cash equivalents		2,508	1,767	$ 1,725	$ 2,037
Total investments and cash		34,855	29,240
Due from subsidiaries	[1]	170	98
Income taxes receivable		337	176
Other assets		405	390
Total assets		35,767	29,904
Liabilities:
Employee benefit plans		323	310
Notes payable		6,136	5,765
Other liabilities		349	367
Total liabilities		6,808	6,442
Shareholders' equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2019 and 2018; issued 1,349,309 shares in 2019 and 1,347,540 shares in 2018		135	135
Additional paid-in capital		2,313	2,177
Retained earnings		34,291	31,788
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains (losses)		(1,623)	(1,847)
Unrealized gains (losses) on fixed maturity securities		8,548	4,234
Unrealized gains (losses) on derivatives		(33)	(24)
Pension liability adjustment		(277)	(212)
Treasury stock, at average cost		(14,395)	(12,789)
Total shareholders' equity		28,959	23,462
Total liabilities and shareholders' equity		$ 35,767	$ 29,904

[1]	Eliminated in consolidation

Schedule II - Aflac Incorpora_4

Schedule II - Aflac Incorporated (Parent Only) - Condensed Balance Sheet (Detail 2) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Available for sale, fixed maturity securities, amortized cost	$ 79,371	$ 76,856
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	1,900,000	1,900,000
Common stock, shares issued (in shares)	1,349,309	1,347,540	1,345,762	1,342,498
Parent Company
Condensed Financial Statements, Captions [Line Items]
Available for sale, fixed maturity securities, amortized cost	$ 1,506	$ 1,209
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	1,900,000	1,900,000
Common stock, shares issued (in shares)	1,349,309	1,347,540

Schedule II - Aflac Incorpora_5

Schedule II - Aflac Incorporated (Parent Only) - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net earnings		$ 3,304	$ 2,920	$ 4,604
Adjustments to reconcile net earnings to net cash provided from operating activities:
Other, net		358	571	150
Net cash provided (used) by operating activities		5,455	6,014	6,128
Cash flows from investing activities:
Fixed maturity securities purchased		(6,934)	(9,086)	(9,867)
Other investments sold (purchased)		(653)	(414)	(206)
Settlement of derivatives		(9)	(241)	(621)
Other, net		(123)	176	(68)
Net cash provided (used) by investing activities		(3,171)	(3,582)	(5,431)
Cash flows from financing activities:
Purchases of treasury stock		(1,627)	(1,301)	(1,351)
Proceeds from borrowings		615	1,020	1,040
Principal payments under debt obligations		0	(550)	(1,161)
Dividends paid to shareholders		(771)	(793)	(661)
Treasury stock reissued		49	58	33
Proceeds from exercise of stock options		40	48	58
Other, net		22	(19)	0
Net cash provided (used) by financing activities		(1,713)	(1,616)	(2,065)
Net change in cash and cash equivalents		559	846	(1,368)
Cash and cash equivalents, beginning of period		4,337	3,491	4,859
Cash and cash equivalents, end of period		4,896	4,337	3,491
Parent Company
Cash flows from operating activities:
Net earnings		3,304	2,920	4,604
Adjustments to reconcile net earnings to net cash provided from operating activities:
Equity in earnings of subsidiaries	[1]	(3,373)	(3,074)	(4,627)
Cash dividends received from subsidiaries		3,466	1,820	2,001
Other, net		(203)	99	(46)
Net cash provided (used) by operating activities		3,194	1,765	1,932
Cash flows from investing activities:
Fixed maturity securities sold		340	207	263
Fixed maturity securities purchased		(639)	(254)	(329)
Other investments sold (purchased)		(16)	31	(47)
Settlement of derivatives		22	(2)	223
Additional capitalization of subsidiaries	[1]	(214)	(62)	(69)
Other, net		87	(107)	(218)
Net cash provided (used) by investing activities		(420)	(187)	(177)
Cash flows from financing activities:
Purchases of treasury stock		(1,627)	(1,301)	(1,351)
Proceeds from borrowings		347	1,020	1,040
Principal payments under debt obligations		0	(550)	(1,161)
Dividends paid to shareholders		(771)	(793)	(661)
Treasury stock reissued		49	58	33
Proceeds from exercise of stock options		29	34	38
Net change in amount due to/from subsidiary	[1]	(58)	(4)	(5)
Other, net		(2)	0	0
Net cash provided (used) by financing activities		(2,033)	(1,536)	(2,067)
Net change in cash and cash equivalents		741	42	(312)
Cash and cash equivalents, beginning of period		1,767	1,725	2,037
Cash and cash equivalents, end of period		$ 2,508	$ 1,767	$ 1,725

[1]	Eliminated in consolidation

Schedule II - Aflac Incorpora_6

Schedule II - Aflac Incorporated (Parent Only) - Summary of Notes Payable (Detail 1) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Notes payable		$ 6,408	$ 5,765
Parent Company
Condensed Financial Statements, Captions [Line Items]
Notes payable		6,136	5,765
Parent Company \| 4.00% senior notes due February 2022
Condensed Financial Statements, Captions [Line Items]
Notes payable	[1]	348	348
Parent Company \| 3.625% senior notes due June 2023
Condensed Financial Statements, Captions [Line Items]
Notes payable		698	698
Parent Company \| 3.625% senior notes due November 2024
Condensed Financial Statements, Captions [Line Items]
Notes payable		747	746
Parent Company \| 3.25% senior notes due March 2025
Condensed Financial Statements, Captions [Line Items]
Notes payable		448	447
Parent Company \| 2.875% senior notes due October 2026
Condensed Financial Statements, Captions [Line Items]
Notes payable		298	297
Parent Company \| 6.90% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable		220	220
Parent Company \| 6.45% senior notes due August 2040
Condensed Financial Statements, Captions [Line Items]
Notes payable		254	254
Parent Company \| 4.00% senior notes due October 2046
Condensed Financial Statements, Captions [Line Items]
Notes payable		394	394
Parent Company \| 4.750% senior notes due January 2049
Condensed Financial Statements, Captions [Line Items]
Notes payable		541	540
Parent Company \| .932% senior notes due January 2027
Condensed Financial Statements, Captions [Line Items]
Notes payable		545	538
Parent Company \| .500% senior notes due December 2029
Condensed Financial Statements, Captions [Line Items]
Notes payable		114	0
Parent Company \| 1.159% senior notes due October 2030
Condensed Financial Statements, Captions [Line Items]
Notes payable		266	262
Parent Company \| .843% senior notes due December 2031
Condensed Financial Statements, Captions [Line Items]
Notes payable		84	0
Parent Company \| 1.488% senior notes due October 2033
Condensed Financial Statements, Captions [Line Items]
Notes payable		138	136
Parent Company \| .934% senior notes due December 2034
Condensed Financial Statements, Captions [Line Items]
Notes payable		88	0
Parent Company \| 1.750% senior notes due October 2038
Condensed Financial Statements, Captions [Line Items]
Notes payable		81	79
Parent Company \| 1.122% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable		57	0
Parent Company \| 2.108% subordinated notes due October 2047
Condensed Financial Statements, Captions [Line Items]
Notes payable		543	536
Parent Company \| Yen-denominated loan variable interest rate due September 2026
Condensed Financial Statements, Captions [Line Items]
Notes payable		45	45
Parent Company \| Yen-denominated loan variable interest rate due September 2029
Condensed Financial Statements, Captions [Line Items]
Notes payable		$ 227	$ 225

[1]	Redeemed in January 2020

Schedule II - Aflac Incorpora_7

Schedule II - Aflac Incorporated (Parent Only) - Summary of Notes Payable (Detail 2) $ in Millions, ¥ in Billions	Dec. 31, 2019USD ($)	Dec. 31, 2019JPY (¥)	Sep. 30, 2019JPY (¥)	Dec. 31, 2018JPY (¥)	Oct. 31, 2018USD ($)	Oct. 31, 2018JPY (¥)	Oct. 31, 2017JPY (¥)	Jan. 31, 2017JPY (¥)	Dec. 31, 2016	Sep. 30, 2016USD ($)	Mar. 31, 2015USD ($)	Nov. 30, 2014USD ($)	Jun. 30, 2013USD ($)	Feb. 29, 2012USD ($)	Aug. 31, 2010USD ($)	Dec. 31, 2009USD ($)
4.00% senior notes due February 2022
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	4.00%	4.00%		4.00%										4.00%
Debt instrument, principal amount \| $	$ 350													$ 350
3.625% senior notes due June 2023
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	3.625%	3.625%		3.625%									3.625%
Debt instrument, principal amount \| $	$ 700												$ 700
3.625% senior notes due November 2024
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	3.625%	3.625%		3.625%								3.625%
Debt instrument, principal amount \| $	$ 750											$ 750
3.25% senior notes due March 2025
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	3.25%	3.25%		3.25%							3.25%
Debt instrument, principal amount \| $	$ 450										$ 450
2.875% senior notes due October 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	2.875%	2.875%		2.875%						2.875%
Debt instrument, principal amount \| $										$ 300
6.90% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	6.90%	6.90%		6.90%					6.90%
Debt instrument, principal amount \| $																$ 400
6.45% senior notes due August 2040
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	6.45%	6.45%		6.45%					6.45%
Debt instrument, principal amount \| $															$ 450
4.00% senior notes due October 2046
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	4.00%	4.00%		4.00%						4.00%
Debt instrument, principal amount \| $										$ 400
4.750% senior notes due January 2049
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	4.75%	4.75%		4.75%	4.75%	4.75%
Debt instrument, principal amount \| $					$ 550
.932% senior notes due January 2027
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.932%	0.932%		0.932%				0.932%
Debt instrument, principal amount		¥ 60		¥ 60				¥ 60
.500% senior notes due December 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.50%	0.50%
Debt instrument, principal amount		¥ 12.6
1.159% senior notes due October 2030
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	1.159%	1.159%		1.159%	1.159%	1.159%
Debt instrument, principal amount		¥ 29.3		¥ 29.3		¥ 29.3
.843% senior notes due December 2031
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.843%	0.843%
Debt instrument, principal amount		¥ 9.3
1.488% senior notes due October 2033
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	1.488%	1.488%		1.488%	1.488%	1.488%
Debt instrument, principal amount		¥ 15.2		¥ 15.2		¥ 15.2
.934% senior notes due December 2034
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.934%	0.934%
Debt instrument, principal amount		¥ 9.8
1.750% senior notes due October 2038
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	1.75%	1.75%		1.75%	1.75%	1.75%
Debt instrument, principal amount		¥ 8.9		¥ 8.9		¥ 8.9
1.122% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	1.122%	1.122%
Debt instrument, principal amount		¥ 6.3
2.108% subordinated notes due October 2047
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	2.108%	2.108%		2.108%			2.108%
Debt instrument, principal amount		¥ 60		¥ 60			¥ 60
Yen-denominated loan variable interest rate due September 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.42%	0.42%		0.32%
Debt instrument, principal amount		¥ 5	¥ 5	¥ 5
Yen-denominated loan variable interest rate due September 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.57%	0.57%		0.47%
Debt instrument, principal amount		¥ 25	25	¥ 25
Parent Company \| 4.00% senior notes due February 2022
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	4.00%	4.00%		4.00%
Parent Company \| 3.625% senior notes due June 2023
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	3.625%	3.625%		3.625%
Parent Company \| 3.625% senior notes due November 2024
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	3.625%	3.625%		3.625%
Parent Company \| 3.25% senior notes due March 2025
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	3.25%	3.25%		3.25%
Parent Company \| 2.875% senior notes due October 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	2.875%	2.875%		2.875%
Parent Company \| 6.90% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	6.90%	6.90%		6.90%
Parent Company \| 6.45% senior notes due August 2040
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	6.45%	6.45%		6.45%
Parent Company \| 4.00% senior notes due October 2046
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	4.00%	4.00%		4.00%
Parent Company \| 4.750% senior notes due January 2049
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	4.75%	4.75%		4.75%
Parent Company \| .932% senior notes due January 2027
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.932%	0.932%		0.932%
Debt instrument, principal amount		¥ 60		¥ 60
Parent Company \| .500% senior notes due December 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.50%	0.50%
Debt instrument, principal amount		¥ 12.6
Parent Company \| 1.159% senior notes due October 2030
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	1.159%	1.159%		1.159%
Debt instrument, principal amount		¥ 29.3		¥ 29.3
Parent Company \| .843% senior notes due December 2031
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.843%	0.843%
Debt instrument, principal amount		¥ 9.3
Parent Company \| 1.488% senior notes due October 2033
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	1.488%	1.488%		1.488%
Debt instrument, principal amount		¥ 15.2		¥ 15.2
Parent Company \| .934% senior notes due December 2034
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.934%	0.934%
Debt instrument, principal amount		¥ 9.8
Parent Company \| 1.750% senior notes due October 2038
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	1.75%	1.75%		1.75%
Debt instrument, principal amount		¥ 8.9		¥ 8.9
Parent Company \| 1.122% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	1.122%	1.122%
Debt instrument, principal amount		¥ 6.3
Parent Company \| 2.108% subordinated notes due October 2047
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	2.108%	2.108%		2.108%
Debt instrument, principal amount		¥ 60		¥ 60
Parent Company \| Yen-denominated loan variable interest rate due September 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.42%	0.42%		0.32%
Debt instrument, principal amount		¥ 5	5	¥ 5
Parent Company \| Yen-denominated loan variable interest rate due September 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	0.57%	0.57%		0.47%
Debt instrument, principal amount		¥ 25	¥ 25	¥ 25

Schedule II - Aflac Incorpora_8

Schedule II - Aflac Incorporated (Parent Only) - Additional Information (Detail) $ in Millions, ¥ in Billions	1 Months Ended
	Sep. 30, 2019JPY (¥)	Dec. 31, 2019JPY (¥)series	Dec. 31, 2018JPY (¥)	Oct. 31, 2018JPY (¥)series	Sep. 30, 2016USD ($)series
Condensed Financial Statements, Captions [Line Items]
Number of series of senior notes issued through a U.S. public debt offering (in series) \| series		4		3	2
Senior Notes
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 38		¥ 53.4	$ 700
.500% senior notes due December 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 12.6
Debt instrument, interest rate		0.50%
.843% senior notes due December 2031
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 9.3
Debt instrument, interest rate		0.843%
.934% senior notes due December 2034
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 9.8
Debt instrument, interest rate		0.934%
1.122% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 6.3
Debt instrument, interest rate		1.122%
Yen-denominated loans
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount	¥ 30
Yen-denominated loan variable interest rate due September 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount	¥ 5	¥ 5	¥ 5
Debt instrument, interest rate		0.42%	0.32%
Debt instrument, description of variable rate basis	bears interest at a rate per annum equal to the Tokyo interbank market rate (TIBOR), or alternate TIBOR, if applicable, plus the applicable TIBOR margin
Yen-denominated loan variable interest rate due September 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount	¥ 25	¥ 25	¥ 25
Debt instrument, interest rate		0.57%	0.47%
Debt instrument, description of variable rate basis	bears interest at a rate per annum equal to the TIBOR, or alternate TIBOR, if applicable, plus the applicable TIBOR margin
Parent Company
Condensed Financial Statements, Captions [Line Items]
Number of series of senior notes issued through a U.S. public debt offering (in series) \| series		4
Parent Company \| Senior Notes
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 38
Parent Company \| .500% senior notes due December 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 12.6
Debt instrument, interest rate		0.50%
Parent Company \| .843% senior notes due December 2031
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 9.3
Debt instrument, interest rate		0.843%
Parent Company \| .934% senior notes due December 2034
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 9.8
Debt instrument, interest rate		0.934%
Parent Company \| 1.122% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 6.3
Debt instrument, interest rate		1.122%
Parent Company \| Yen-denominated loans
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount	¥ 30
Parent Company \| Yen-denominated loan variable interest rate due September 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount	¥ 5	¥ 5	¥ 5
Debt instrument, interest rate		0.42%	0.32%
Debt instrument, description of variable rate basis	bears interest at a rate per annum equal to the Tokyo interbank market rate (TIBOR), or alternate TIBOR, if applicable, plus the applicable TIBOR margin
Parent Company \| Yen-denominated loan variable interest rate due September 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount	¥ 25	¥ 25	¥ 25
Debt instrument, interest rate		0.57%	0.47%
Debt instrument, description of variable rate basis	bears interest at a rate per annum equal to the TIBOR, or alternate TIBOR, if applicable, plus the applicable TIBOR margin
Lower Limit \| Yen-denominated loan variable interest rate due September 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, basis spread on variable rate	0.30%
Lower Limit \| Yen-denominated loan variable interest rate due September 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, basis spread on variable rate	0.45%
Lower Limit \| Parent Company \| Yen-denominated loan variable interest rate due September 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, basis spread on variable rate	0.30%
Lower Limit \| Parent Company \| Yen-denominated loan variable interest rate due September 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, basis spread on variable rate	0.45%
Upper Limit \| Yen-denominated loan variable interest rate due September 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, basis spread on variable rate	0.70%
Upper Limit \| Yen-denominated loan variable interest rate due September 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, basis spread on variable rate	1.00%
Upper Limit \| Parent Company \| Yen-denominated loan variable interest rate due September 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, basis spread on variable rate	0.70%
Upper Limit \| Parent Company \| Yen-denominated loan variable interest rate due September 2029
Condensed Financial Statements, Captions [Line Items]
Debt instrument, basis spread on variable rate	1.00%

Schedule II - Aflac Incorpora_9

Schedule II - Aflac Incorporated - Aggregate Contractual Maturities of Notes Payable (Detail) $ in Millions	Dec. 31, 2019USD ($)
Condensed Financial Statements, Captions [Line Items]
2020	$ 0
2021	0
2022	350
2023	700
2024	750
Thereafter	4,658
Total	6,458
Parent Company
Condensed Financial Statements, Captions [Line Items]
2020	0
2021	0
2022	350
2023	700
2024	750
Thereafter	4,386
Total	$ 6,186

Schedule II - Aflac Incorpor_10

Schedule II - Aflac Incorporated (Parent Only) - Supplemental Disclosure of Cash Flow Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shareholder dividend reinvestment
Condensed Cash Flow Statements, Captions [Line Items]
Treasury stock issued for shareholder dividend reinvestment	$ 30	$ 8	$ 29
Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Interest paid	189	179	195
Parent Company \| Shareholder dividend reinvestment
Condensed Cash Flow Statements, Captions [Line Items]
Treasury stock issued for shareholder dividend reinvestment	$ 30	$ 8	$ 29

SCHEDULE III SUPPLEMENTARY IN_2

SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION - (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	$ 10,128				$ 9,875				$ 10,128	$ 9,875
Future policy benefits & unpaid policy claims	94,994				90,952				94,994	90,952
Unearned premiums	4,243				5,090				4,243	5,090
Other policyholders' funds	7,317				7,146				7,317	7,146
Premiums Earned, Net	4,671	$ 4,736	$ 4,681	$ 4,691	4,591	$ 4,636	$ 4,706	$ 4,745	18,780	18,677	$ 18,531
Net investment income	886	$ 936	$ 878	$ 878	874	$ 870	$ 862	$ 837	3,578	3,442	3,220
Benefits and claims, net									11,942	12,000	12,181
Amortization of deferred policy acquisition costs									1,282	1,245	1,132
Other operating expenses									4,638	4,530	4,336
Premiums written									18,180	18,005	17,657
Aflac Japan
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	6,584				6,384				6,584	6,384	6,150
Future policy benefits & unpaid policy claims	84,341				80,672				84,341	80,672
Unearned premiums	4,135				4,977				4,135	4,977
Other policyholders' funds	7,317				7,145				7,317	7,145
Premiums Earned, Net									12,772	12,762	12,752
Net investment income									2,753	2,639	2,463
Benefits and claims, net									8,877	8,913	9,087
Amortization of deferred policy acquisition costs									709	710	630
Other operating expenses									2,465	2,374	2,257
Premiums written									12,367	12,298	12,092
Aflac U.S.
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	3,544				3,491				3,544	3,491	3,355
Future policy benefits & unpaid policy claims	11,184				10,864				11,184	10,864
Unearned premiums	111				117				111	117
Other policyholders' funds	0				0				0	0
Premiums Earned, Net									5,808	5,708	5,563
Net investment income									720	727	721
Benefits and claims, net									2,871	2,887	2,885
Amortization of deferred policy acquisition costs									573	534	502
Other operating expenses									1,834	1,736	1,658
Premiums written									5,813	5,707	5,565
All other
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	0				0				0	0
Future policy benefits & unpaid policy claims	223				183				223	183
Unearned premiums	0				0				0	0
Other policyholders' funds	0				1				0	1
Premiums Earned, Net									200	207	216
Net investment income									105	76	36
Benefits and claims, net									194	200	209
Amortization of deferred policy acquisition costs									0	1	0
Other operating expenses									339	420	421
Premiums written									0	0	$ 0
Intercompany eliminations
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	0				0				0	0
Future policy benefits & unpaid policy claims	(754)				(767)				(754)	(767)
Unearned premiums	(3)				(4)				(3)	(4)
Other policyholders' funds	$ 0				$ 0				$ 0	$ 0

SCHEDULE IV REINSURANCE Schedul

SCHEDULE IV REINSURANCE Schedule IV - Reinsurance (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross Amount, Life Insurance in Force	$ 146,585				$ 151,457				$ 146,585	$ 151,457	$ 152,502
Ceded to Other Companies, Life Insurance in Force	6,592				4,702				6,592	4,702	4,121
Assumed from Other Companies, Life Insurance in Force	0				0				0	0	0
Net Amount, Life Insurance in Force	$ 139,993				$ 146,755				$ 139,993	$ 146,755	$ 148,381
Percentage of Amount Assumed to Net, Life Insurance in Force	0.00%				0.00%				0.00%	0.00%	0.00%
Gross amount									$ 19,122	$ 19,018	$ 18,875
Ceded to Other Companies									547	555	566
Assumed from Other companies									205	214	222
Net Amount	$ 4,671	$ 4,736	$ 4,681	$ 4,691	$ 4,591	$ 4,636	$ 4,706	$ 4,745	$ 18,780	$ 18,677	$ 18,531
Percentage of Amount Assumed to Net									1.00%	1.00%	1.00%
Health insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross amount									$ 15,657	$ 15,330	$ 14,829
Ceded to Other Companies									527	541	554
Assumed from Other companies									205	214	222
Net Amount									$ 15,335	$ 15,003	$ 14,497
Percentage of Amount Assumed to Net									1.00%	1.00%	1.00%
Life insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross amount									$ 3,465	$ 3,688	$ 4,046
Ceded to Other Companies									20	14	12
Assumed from Other companies									0	0	0
Net Amount									$ 3,445	$ 3,674	$ 4,034
Percentage of Amount Assumed to Net									0.00%	0.00%	0.00%