Amkor Technology (AMKR) 10-Q1 May 242024 Q1 Quarterly reportFinancial data

Company Profile

COVER PAGE

COVER PAGE - shares	3 Months Ended
COVER PAGE - shares	Mar. 31, 2024	Apr. 25, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	000-29472
Entity Registrant Name	AMKOR TECHNOLOGY, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	23-1722724
Entity Address, Address Line One	2045 East Innovation Circle
Entity Address, City or Town	Tempe
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85284
City Area Code	480
Local Phone Number	821-5000
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	AMKR
Security Exchange Name	NASDAQ
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 Common Stock, Shares Outstanding		246,170,251
Entity Central Index Key	0001047127
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Net sales	$ 1,365,511	$ 1,471,539
Cost of sales	1,163,868	1,277,118
Gross profit	201,643	194,421
Selling, general and administrative	90,346	78,671
Research and development	38,171	47,047
Total operating expenses	128,517	125,718
Operating income	73,126	68,703
Interest expense	16,439	16,167
Other (income) expense, net	(15,295)	(3,552)
Total other expense, net	1,144	12,615
Income before taxes	71,982	56,088
Income tax expense	12,196	10,864
Net income	59,786	45,224
Net (income) loss attributable to non-controlling interests	(889)	127
Net income attributable to Amkor	$ 58,897	$ 45,351
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.24	$ 0.18
Diluted (in dollars per share)	$ 0.24	$ 0.18
Shares used in computing per common share amounts:
Basic (in shares)	246,008	245,330
Diluted (in shares)	247,614	247,087

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 59,786	$ 45,224
Other comprehensive income (loss), net of tax:
Adjustments to net unrealized gains (losses) on available-for-sale debt investments	(308)	601
Adjustments to unrealized components of defined benefit pension plans	(85)	(97)
Foreign currency translation	(9,047)	(2,113)
Total other comprehensive income (loss)	(9,440)	(1,609)
Comprehensive income	50,346	43,615
Comprehensive (income) loss attributable to non-controlling interests	(889)	127
Comprehensive income attributable to Amkor	$ 49,457	$ 43,742

CONSOLIDATED BALANCE SHEETS (Un

CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 1,118,004	$ 1,119,818
Short-term investments (amortized cost of $454,767 and $474,663 in 2.024 and 2023, respectively)	454,669	474,869
Accounts receivable, net of allowances	1,093,960	1,149,493
Inventories	331,070	393,128
Other current assets	47,312	58,502
Total current assets	3,045,015	3,195,810
Property, plant and equipment, net	3,367,434	3,299,445
Operating lease right of use assets	106,873	117,006
Goodwill	18,641	20,003
Restricted cash	781	799
Other assets	146,322	138,062
Total assets	6,685,066	6,771,125
Current liabilities:
Short-term borrowings and current portion of long-term debt	112,968	131,624
Trade accounts payable	618,378	754,453
Capital expenditures payable	234,762	106,368
Short-term operating lease liability	27,112	33,616
Accrued expenses	309,976	358,414
Total current liabilities	1,303,196	1,384,475
Long-term debt	1,038,346	1,071,832
Pension and severance obligations	79,647	87,133
Long-term operating lease liabilities	52,924	56,837
Other non-current liabilities	180,345	175,813
Total liabilities	2,654,458	2,776,090
Commitments and contingencies (Note 15)
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000 shares authorized, designated Series A, none issued	0	0
Common stock, $0.001 par value, 500,000 shares authorized; 292,494 and 292,167 shares issued; and 246,154 and 245,888 shares outstanding in 2.024 and 2023, respectively	292	292
Additional paid-in capital	2,014,782	2,008,170
Retained earnings	2,199,300	2,159,831
Accumulated other comprehensive income (loss)	6,910	16,350
Treasury stock, at cost, 46,340 and 46,279 shares in 2.024 and 2023, respectively	(224,157)	(222,335)
Total Amkor stockholders’ equity	3,997,127	3,962,308
Non-controlling interests in subsidiaries	33,481	32,727
Total equity	4,030,608	3,995,035
Total liabilities and equity	$ 6,685,066	$ 6,771,125

CONSOLIDATED BALANCE SHEETS (_2

CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Short term investments amortized cost	$ 454,767	$ 474,663
Stockholders’ equity:
Preferred stock designated Series A, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock designated Series A, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock designated Series A, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	292,494,000	292,167,000
Common stock, shares outstanding (in shares)	246,154,000	245,888,000
Treasury stock, shares (in shares)	46,340,000	46,279,000

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Total Amkor Stockholders’ Equity	Common Stock	Additional Paid- In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interest in Subsidiaries
Balance at beginning of period, common stock (in shares) at Dec. 31, 2022			291,249
Balance at beginning of period at Dec. 31, 2022	$ 3,699,701	$ 3,668,752	$ 291	$ 1,996,344	$ 1,874,644	$ 16,699	$ (219,226)	$ 30,949
Balance at beginning of period, treasury stock (in shares) at Mar. 31, 2023							(46,269)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	45,224	45,351			45,351			(127)
Other comprehensive income (loss)	(1,609)	(1,609)				(1,609)
Treasury stock acquired through surrender of shares for tax withholding (in shares)							(111)
Treasury stock acquired through surrender of shares for tax withholding	(2,823)	(2,823)					$ (2,823)
Issuance of stock through share-based compensation plans (in shares)			565
Issuance of stock through share-based compensation plans	1,524	1,524	$ 1	1,523
Share-based compensation	3,708	3,708		3,708
Cash Dividends declared	(18,426)	(18,426)			(18,426)
Subsidiary dividends to non-controlling interests	(136)							(136)
Balance at end of period, common stock (in shares) at Mar. 31, 2023			291,814
Balance at end of period at Mar. 31, 2023	$ 3,727,163	3,696,477	$ 292	2,001,575	1,901,569	15,090	$ (222,049)	30,686
Balance at end of period, treasury stock (in shares) at Dec. 31, 2022							(46,158)
Balance at beginning of period, common stock (in shares) at Dec. 31, 2023	245,888		292,167
Balance at beginning of period at Dec. 31, 2023	$ 3,995,035	3,962,308	$ 292	2,008,170	2,159,831	16,350	$ (222,335)	32,727
Balance at beginning of period, treasury stock (in shares) at Mar. 31, 2024	(46,340)						(46,340)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 59,786	58,897			58,897			889
Other comprehensive income (loss)	(9,440)	(9,440)				(9,440)
Treasury stock acquired through surrender of shares for tax withholding (in shares)							(61)
Treasury stock acquired through surrender of shares for tax withholding	(1,822)	(1,822)					$ (1,822)
Issuance of stock through share-based compensation plans (in shares)			327
Issuance of stock through share-based compensation plans	1,356	1,356		1,356
Share-based compensation	5,256	5,256		5,256
Cash Dividends declared	(19,428)	(19,428)			(19,428)
Subsidiary dividends to non-controlling interests	$ (135)							(135)
Balance at end of period, common stock (in shares) at Mar. 31, 2024	246,154		292,494
Balance at end of period at Mar. 31, 2024	$ 4,030,608	$ 3,997,127	$ 292	$ 2,014,782	$ 2,199,300	$ 6,910	$ (224,157)	$ 33,481
Balance at end of period, treasury stock (in shares) at Dec. 31, 2023	(46,279)						(46,279)

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per common share (in dollars per share)	$ 0.07875	$ 0.075

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net income	$ 59,786	$ 45,224
Depreciation and amortization	144,925	156,762
Other operating activities and non-cash items	14,100	(2,821)
Changes in assets and liabilities	(56,499)	(23,419)
Net cash provided by operating activities	162,312	175,746
Cash flows from investing activities:
Payments for property, plant and equipment	(96,169)	(98,224)
Proceeds from sale of property, plant and equipment	3,439	652
Proceeds from foreign exchange forward contracts	740	20,267
Payments for foreign exchange forward contracts	(24,596)	(20,358)
Payments for short-term investments	(111,760)	(172,409)
Proceeds from sale of short-term investments	16,014	21,549
Proceeds from maturities of short-term investments	121,684	92,655
Other investing activities	4,545	164
Net cash used in investing activities	(86,103)	(155,704)
Cash flows from financing activities:
Proceeds from revolving credit facilities	0	370,000
Payments of revolving credit facilities	0	(370,000)
Proceeds from short-term debt	5,012	11,042
Payments of short-term debt	(5,669)	(5,840)
Payments of long-term debt	(29,100)	(35,980)
Payments of finance lease obligations	(19,684)	(15,148)
Payments of dividends	(19,383)	(18,430)
Other financing activities	(1,053)	(1,850)
Net cash used in financing activities	(69,877)	(66,206)
Effect of exchange rate fluctuations on cash, cash equivalents and restricted cash	(8,164)	(2,943)
Net decrease in cash, cash equivalents and restricted cash	(1,832)	(49,107)
Cash, cash equivalents and restricted cash, beginning of period	1,120,617	962,406
Cash, cash equivalents and restricted cash, end of period	1,118,785	913,299
Non-cash investing and financing activities:
Property, plant and equipment included in capital expenditures payable	195,405	177,615
Right of use assets acquired through finance lease liabilities	17,811	17,513
Right of use assets acquired through operating lease liabilities	$ 2,321	$ 3,180

Interim Financial Statements

Interim Financial Statements	3 Months Ended
Interim Financial Statements	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Interim Financial Statements	Interim Financial Statements Basis of Presentation. The Consolidated Financial Statements and related disclosures as of March 31, 2024, and for the three months ended March 31, 2024 and 2023, contained in this Form 10-Q (the “Consolidated Financial Statements”) are unaudited pursuant to the rules and regulations of the SEC. The December 31, 2023 Consolidated Balance Sheet data contained in this Form 10-Q was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S. GAAP”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to SEC rules and regulations. In our opinion, the Consolidated Financial Statements include all adjustments (consisting only of normal recurring adjustments) necessary for the fair statement of the results for the interim periods and should be read in conjunction with the financial statements included in the 2023 Form 10-K. The results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results to be expected for the full year ending December 31, 2024. Unless the context otherwise requires, all references to “Amkor,” “we,” “us” or “our” are to Amkor Technology, Inc. and its wholly and majority-owned subsidiaries. Use of Estimates. The Consolidated Financial Statements have been prepared in conformity with U.S. GAAP, using management’s best estimates and judgments where appropriate. These estimates and judgments affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. The estimates and judgments will also affect the reported amounts for certain revenues and expenses during the reporting period. Actual results could differ materially from these estimates and judgments as a result of, for example, any worsening of the global business and economic environment. Leases. Total long-term finance lease liabilities as of March 31, 2024 and December 31, 2023 were $49.7 million and $47.8 million, respectively. Goodwill. The balance of goodwill in the Consolidated Balance Sheets contained in this Form 10-Q reflects adjustments for foreign currency translation. Unbilled Receivables . Total unbilled receivables as of March 31, 2024 and December 31, 2023 were $229.8 million and $260.8 million, respectively. Contract Liabilities. Contract liabilities were $123.6 million and $135.5 million as of March 31, 2024 and December 31, 2023, respectively. As of March 31, 2024 and December 31, 2023, the short-term portions of the liabilities were $67.4 million and $71.1 million, respectively. The remainder of the March 31, 2024 contract liability balance is expected to be recognized in revenue over the next 1-5 years. Revenue recognized during the three months ended March 31, 2024 and 2023 that was included in the contract liabilities balance at the beginning of the period was $18.9 million and $21.5 million, respectively. Share-based compensation. In February 2024, long-term incentive awards were granted in the form of time-vested restricted stock units (“RSUs”) and performance-vested restricted stock units (“PSUs”) to our management pursuant to the 2021 Equity Plan with different terms from those issued in prior years. For a description of the RSUs and PSUs granted in prior years, please refer to our Consolidated Financial Statements in Part II, Item 8, Note 2 of the 2023 Form 10-K. The RSUs granted in the first quarter of 2024 will generally vest in three equal installments on the anniversary of the grant date, subject to the recipient’s continued employment with the Company at the time of vesting. The value of the RSUs is determined based on the fair market value of the underlying shares on the date of the grant, reduced by the present value of dividends or dividend equivalent rights expected to be paid on our common stock prior to vesting. The PSUs granted in the first quarter of 2024 are divided between PSUs based on earnings per share in each of 2024, 2025 and 2026 (“EPS PSUs”), and PSUs based on relative total shareholder return (“rTSR PSUs”), compared to the components of the PHLX Semiconductor Index (the “SOX”) over a three-year period, with half of the awards as EPS PSUs and half as rTSR PSUs. For the EPS PSUs, the value is determined based on the fair market value of the underlying shares on the date of the grant, reduced by the present value of dividends or dividend equivalent rights expected to be paid on our common stock prior to vesting. The number of shares of our common stock to be received annually at vesting will range from 0% to 225%. For the rTSR PSUs, the Company estimated the grant-date fair value of the PSUs subject to a market condition using a Monte Carlo simulation model, using the following weighted-average assumptions: risk-free interest rate of 4.33% and annualized volatility of 46.77%. The grant date fair value of the PSUs was $27.07. The number of shares of our common stock to be received at vesting will range from 0% to 150% of the target grant amount based on rTSR performance over the three-year performance period. The Company recognizes the grant date fair value of the PSUs as compensation expense ratably over the vesting period. Recently Issued Standards. In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires disclosure of additional income tax information, primarily related to effective tax rate reconciliation and income taxes paid. ASU 2023-09 is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. Adoption of this ASU should be applied on a prospective basis, but retrospective application is permitted. We are currently evaluating the impact of this new standard on our financial statements, which is expected to result in enhanced disclosures.

Net Sales by Product Group and

Net Sales by Product Group and End Market	3 Months Ended
Net Sales by Product Group and End Market	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Net Sales by Product Group and End Market	Net Sales by Product Group and End Market The following table presents our net sales by product group: For the Three Months Ended March 31, 2024 2023 (In thousands) Advanced products (1) $ 1,069,709 $ 1,067,377 Mainstream products (2) 295,802 404,162 Total net sales $ 1,365,511 $ 1,471,539 (1) Advanced products include flip chip, memory and wafer-level processing and related test services. (2) Mainstream products include all other wirebond packaging and related test services. Net sales by end market consist of the following: For the Three Months Ended March 31, 2024 2023 Communications (smartphones, tablets) 47 % 45 % Automotive, industrial and other (ADAS, electrification, infotainment, safety) 22 % 26 % Computing (data center, infrastructure, PC/laptop, storage) 17 % 17 % Consumer (AR & gaming, connected home, home electronics, wearables) 14 % 12 % Total net sales 100 % 100 %

Other Income and Expense

Other Income and Expense	3 Months Ended
Other Income and Expense	Mar. 31, 2024
Other Income and Expenses [Abstract]
Other Income and Expense	Other Income and Expense Other income and expense consist of the following: For the Three Months Ended March 31, 2024 2023 (In thousands) Interest income $ (16,796) $ (10,433) Foreign currency loss (gain), net 1,545 6,763 Other, net (44) 118 Total other (income) expense, net $ (15,295) $ (3,552)

Income Taxes

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense of $12.2 million for the three months ended March 31, 2024 reflects income taxes, foreign withholding taxes and minimum taxes. We monitor on an ongoing basis our ability to utilize our deferred tax assets and whether there is a need for a related valuation allowance. In evaluating our ability to recover our deferred tax assets in the jurisdictions from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies and recent results of operations. We maintain a valuation allowance on certain U.S. and foreign deferred tax assets. Such valuation allowances are released as the related tax benefits are realized or when sufficient evidence exists to conclude that it is more likely than not that the deferred tax assets will be realized. Unrecognized tax benefits represent reserves for potential tax deficiencies or reductions in tax benefits that could result from federal, state or foreign tax audits. Gross unrecognized tax benefits decreased from $31.5 million as of December 31, 2023 to $30.6 million as of March 31, 2024. All of our unrecognized tax benefits would reduce our effective tax rate if recognized. Our unrecognized tax benefits are subject to change for effective settlement of examinations, changes in the recognition threshold of tax positions, the expiration of statutes of limitations and other factors.

Earnings Per Share

Earnings Per Share	3 Months Ended
Earnings Per Share	Mar. 31, 2024
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic earnings per share (“EPS”) is computed by dividing net income attributable to Amkor common stockholders by the weighted-average number of common shares outstanding during the period. The weighted-average number of common shares outstanding is reduced for treasury stock. Diluted EPS is computed based on the weighted-average number of common shares outstanding plus the effect of dilutive potential common shares outstanding during the period. Dilutive potential common shares include outstanding stock options, performance-vested restricted stock units, time-vested restricted stock units and unvested restricted shares. The following table summarizes the computation of basic and diluted EPS: For the Three Months Ended March 31, 2024 2023 (In thousands, Net income attributable to Amkor common stockholders $ 58,897 $ 45,351 Weighted-average number of common shares outstanding - basic 246,008 245,330 Effect of dilutive securities: Share-based awards 1,606 1,757 Weighted-average number of common shares outstanding - diluted 247,614 247,087 Net income attributable to Amkor per common share: Basic $ 0.24 $ 0.18 Diluted 0.24 0.18 The following table summarizes the potential shares of common stock that were excluded from diluted EPS because the effect of including these potential shares was anti-dilutive: For the Three Months Ended March 31, 2024 2023 (In thousands) Share-based awards 11 —

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
Accumulated Other Comprehensive Income (Loss)	Mar. 31, 2024
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Changes in accumulated other comprehensive income (loss), net of tax, consist of the following: Unrealized Gains (Losses) on Available-for-Sale Debt Investments (1) Defined Benefit Pension (2) Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2023 $ 212 $ 15,905 $ 233 $ 16,350 Other comprehensive income (loss) before reclassifications (253) — (9,047) (9,300) Amounts reclassified from accumulated other comprehensive income (loss) (55) (85) — (140) Other comprehensive income (loss) (308) (85) (9,047) (9,440) Accumulated other comprehensive income (loss) at March 31, 2024 $ (96) $ 15,820 $ (8,814) $ 6,910 Unrealized Gains (Losses) on Available-for-Sale Debt Investments (1) Defined Benefit Pension (2) Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2022 $ (1,573) $ 14,220 $ 4,052 $ 16,699 Other comprehensive income (loss) before reclassifications 645 — (2,113) (1,468) Amounts reclassified from accumulated other comprehensive income (loss) (44) (97) — (141) Other comprehensive income (loss) 601 (97) (2,113) (1,609) Accumulated other comprehensive income (loss) at March 31, 2023 $ (972) $ 14,123 $ 1,939 $ 15,090 (1) Amounts reclassified out of accumulated other comprehensive income (loss) are included as other (income) expense, net (Note 3). (2) Amounts reclassified out of accumulated other comprehensive income (loss) are included as a component of net periodic pension cost (Note 12) or other (income) expense, net (Note 3).

Investments

Investments	3 Months Ended
Investments	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Investments	Investments All of our available-for-sale debt investments as of March 31, 2024 are available to fund current operations and are recorded at fair value (Note 14). The following table summarizes our cash equivalents and available-for-sale debt investments: March 31, 2024 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents Commercial paper $ 51,970 $ — $ — $ 51,970 $ — $ 51,970 Corporate bonds 1,657 — — 1,657 — 1,657 Money market funds 97,440 — — 97,440 97,440 — U.S. government bonds 16,936 — — 16,936 16,936 — Total cash equivalents (2) 168,003 — — 168,003 114,376 53,627 Short-term investments Asset-backed securities 62,076 99 (27) 62,148 — 62,148 Certificate of deposits 19,294 — — 19,294 19,294 — Commercial paper 45,383 — — 45,383 — 45,383 Corporate bonds 255,876 277 (301) 255,852 — 255,852 U.S. government agency bonds 4,729 — (4) 4,725 — 4,725 U.S. government bonds 62,212 — (142) 62,070 62,070 — Total short-term investments 449,570 376 (474) 449,472 81,364 368,108 Total $ 617,573 $ 376 $ (474) $ 617,475 $ 195,740 $ 421,735 December 31, 2023 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents Asset-backed securities $ 138 $ — $ — $ 138 $ — $ 138 Commercial paper 48,063 — — 48,063 — 48,063 Money market funds 60,719 — — 60,719 60,719 — U.S. government bonds 2,996 — — 2,996 2,996 — Total cash equivalents 111,916 — — 111,916 63,715 48,201 Short-term investments Asset-backed securities 65,340 170 (22) 65,488 — 65,488 Certificate of deposits 17,086 — — 17,086 17,086 — Commercial paper 56,273 — — 56,273 — 56,273 Corporate bonds 251,671 432 (299) 251,804 — 251,804 U.S. government agency bonds 13,200 — (9) 13,191 — 13,191 U.S. government bonds 65,881 13 (79) 65,815 65,815 — Total short-term investments 469,451 615 (409) 469,657 82,901 386,756 Total $ 581,367 $ 615 $ (409) $ 581,573 $ 146,616 $ 434,957 (1) All unrealized losses have been in a continuous loss position for less than 12 months. We do not intend to sell the investments in an unrealized loss position, and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost bases. (2) For three months ended March 31, 2024 and 2023, we sold cash equivalent investments for proceeds of $5.8 million and $13.0 million, respectively, and realized no gain or loss on such sales. The following table summarizes the contractual maturities of our cash equivalents and available-for-sale debt investments as of March 31, 2024 : Amortized Cost Fair Value (In thousands) Within 1 year $ 459,067 $ 458,887 After 1 year through 5 years 96,430 96,440 Asset-backed securities 62,076 62,148 Total $ 617,573 $ 617,475 Actual maturities can differ from contractual maturities due to various factors including the issuers may have the right to call or prepay obligations without call or prepayment penalties.

Factoring of Accounts Receivabl

Factoring of Accounts Receivable	3 Months Ended
Factoring of Accounts Receivable	Mar. 31, 2024
Factoring of Accounts Receivable [Abstract]
Factoring of Accounts Receivable	Factoring of Accounts Receivable For certain accounts receivable, we use non-recourse factoring arrangements with third-party financial institutions to manage our working capital and cash flows. Under these arrangements, we sell receivables to a financial institution for cash at a discount to the face amount. As part of the factoring arrangements, we perform certain collection and administrative functions for the receivables sold. For the three months ended March 31, 2024 and 2023, we sold receivables totaling $24.4 million and $78.0 million, respectively, net of discounts and fees. Discounts and fees were insignificant for the three months ended March 31, 2024, and $0.2 million for the three months ended March 31, 2023.

Property, Plant and Equipment

Property, Plant and Equipment	3 Months Ended
Property, Plant and Equipment	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Property, Plant And Equipment	Property, Plant and Equipment Property, plant and equipment consist of the following: March 31, 2024 December 31, 2023 (In thousands) Land $ 211,211 $ 212,722 Buildings and improvements 2,149,095 2,080,589 Machinery and equipment 7,104,414 7,022,614 Finance lease assets 224,983 209,506 Furniture, fixtures and other equipment 22,460 22,655 Software and computer equipment 206,633 200,362 Construction in progress 198,263 223,332 Total property, plant and equipment 10,117,059 9,971,780 Accumulated depreciation and amortization (6,749,625) (6,672,335) Total property, plant and equipment, net $ 3,367,434 $ 3,299,445 The following table summarizes our depreciation expense: For the Three Months Ended March 31, 2024 2023 (In thousands) Depreciation expense $ 144,787 $ 156,614 We periodically assess the estimated useful lives of our property, plant and equipment. Based on our assessment of test equipment and its increased interchangeability enabling broader and longer use, we extended the estimated useful lives of test equipment from five years to seven years as of January 1, 2024. As a result, the reduction in depreciation expense of approximately $15 million benefited net income and diluted earnings per share by approximately $13 million and $0.05 for the first quarter of 2024, respectively.

Accrued Expenses

Accrued Expenses	3 Months Ended
Accrued Expenses	Mar. 31, 2024
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following: March 31, 2024 December 31, 2023 (In thousands) Payroll and benefits $ 95,100 $ 115,604 Deferred revenue and customer advances 67,439 71,117 Short-term finance lease liabilities 52,734 57,761 Income taxes payable 30,471 35,215 Accrued severance plan obligations 7,518 7,906 Accrued interest 2,318 11,175 Other accrued expenses 54,396 59,636 Total accrued expenses $ 309,976 $ 358,414

Debt

Debt	3 Months Ended
Debt	Mar. 31, 2024
Debt Disclosure [Abstract]
Debt	Debt Following is a summary of short-term borrowings and long-term debt: March 31, 2024 December 31, 2023 (In thousands) Debt of Amkor Technology, Inc.: Senior notes: 6.625% Senior notes, due September 2027 $ 525,000 $ 525,000 Debt of subsidiaries: Amkor Technology Korea, Inc.: Term loan, fixed rate at 1.85%, due April 2024 (1) — — Term loan, fixed rate at 2.12%, due December 2028 200,000 200,000 Amkor Technology Japan, Inc.: Short-term term loans, variable rate (2) 4,136 5,098 Term loan, fixed rate at 1.35%, due December 2024 28,246 40,414 Term loan, fixed rate at 1.20%, due December 2025 25,206 30,913 Term loan, fixed rate at 1.23%, due December 2026 47,605 55,729 Term loan, fixed rate at 1.59%, due December 2027 77,800 89,053 Term loan, fixed rate at 1.80%, due December 2028 109,845 124,078 Amkor Assembly & Test (Shanghai) Co., Ltd.: Term loans, SOFR plus 0.75%, weighted average of 6.06% as of March 31, 2024, due June 2025 37,000 37,000 Term loans, SOFR plus 0.75%, weighted average of 6.06% as of March 31, 2024, due 2025 57,000 57,500 Term loans, SOFR plus 0.95%, due December 2026 (3) 45,000 45,000 Other: Credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) (4) — — Senior secured revolving credit facility, applicable bank rate plus 1.75%, due March 2027 (Singapore) (5) — — 1,156,838 1,209,785 Less: Unamortized discount and deferred debt costs, net (5,524) (6,329) Less: Short-term borrowings and current portion of long-term debt (112,968) (131,624) Long-term debt $ 1,038,346 $ 1,071,832 (1) In April 2021, we entered into a ₩80.0 billion term loan agreement with the option to borrow and re-borrow the funds up to six times per year through April 2024. Principal is payable at maturity, and interest is payable monthly, at a fixed rate of 1.85%. As of March 31, 2024, ₩80.0 billion, or approximately $59 million, was available to be drawn. (2) We entered into various short-term term loans which mature semiannually. Principal and interest are payable in monthly installments. Interest as of March 31, 2024 is at an annual base rate equal to the Tokyo Interbank Offered Rate plus 0.18% to 0.20% (weighted average of 0.25% as of March 31, 2024). As of March 31, 2024, $2.9 million was available to be drawn. (3) In February 2024, Amkor Assembly & Test (Shanghai) Co. Ltd. amended the term loan due December 2026 to reduce the interest rate from SOFR plus 1.40% to SOFR plus 0.95% (weighted average of 6.27% as of March 31, 2024). This contractual amendment is treated as a modification with no recognized gain or loss. (4) In March 2022, Amkor Technology Taiwan Ltd. (“ATT”) amended an existing revolving credit facility to reduce availability from $36.0 million to $15.0 million. As of March 31, 2024, $15.0 million was available for future borrowings under such credit facility. (5) In March 2022, Amkor Technology Singapore Holdings Pte. Ltd. (“ATSH”) entered into a $600.0 million senior secured revolving credit facility (the “2022 Singapore Revolver”), which is guaranteed by Amkor Technology, Inc., ATT and Amkor Advanced Technology, Inc. (“AATT”). The maximum borrowing capacity under the 2022 Singapore Revolver is limited to a base amount equal to the lesser of: (1) $600.0 million; or (2) $250.0 million plus a variable amount equal to 37.5% of our consolidated accounts receivable balance. As of March 31, 2024, $600.0 million was available for future borrowings under the 2022 Singapore Revolver. Certain of our foreign debt is collateralized by the land, buildings, equipment and accounts receivable in the respective locations. As of March 31, 2024, the collateralized debt balance was $627.7 million, of which $319.0 million of assets were pledged as collateral. The debt of Amkor Technology, Inc. is structurally subordinated in right of payment to all existing and future debt and other liabilities of our subsidiaries. From time to time, Amkor Technology, Inc., ATT, AATT, and ATSH guarantee certain debt of our subsidiaries. The agreements governing our indebtedness contain affirmative and negative covenants which restrict our ability to pay dividends and could restrict our operations. These restrictions are determined in part by calculations based upon cumulative net income and do not currently have a material impact on our ability to make dividend payments or stock repurchases. We were in compliance with all debt covenants at March 31, 2024.

Pension Plans

Pension Plans	3 Months Ended
Pension Plans	Mar. 31, 2024
Retirement Benefits [Abstract]
Pension Plans	Pension Plans Foreign Defined Benefit Pension Plans Our subsidiaries in Japan, Korea, Malaysia, the Philippines and Taiwan sponsor defined benefit pension plans. Charges to expense are based upon actuarial analyses. The components of net periodic pension cost for these defined benefit pension plans are as follows: For the Three Months Ended March 31, 2024 2023 (In thousands) Service cost $ 3,484 $ 3,828 Interest cost 1,459 1,603 Expected return on plan assets (1,418) (1,311) Recognized actuarial gain (97) (98) Net periodic pension cost $ 3,428 $ 4,022 The components of net periodic pension cost other than the service cost component are included in other (income) expense, net in our Consolidated Statements of Income. Defined Contribution Pension Plans We sponsor defined contribution pension plans in Korea, Malaysia, Taiwan and the U.S. The following table summarizes our defined contribution expense: For the Three Months Ended March 31, 2024 2023 (In thousands) Defined contribution expense $ 8,414 $ 8,796

Derivatives

Derivatives	3 Months Ended
Derivatives	Mar. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives We use foreign currency forward contracts to mitigate foreign currency risk of certain monetary assets and liabilities denominated in foreign currencies. We do not enter into such contracts for trading or speculative purposes. These derivative instruments are not designated as hedging instruments. As of March 31, 2024 and December 31, 2023, our foreign exchange forward contracts consisted of the following: March 31, 2024 December 31, 2023 Notional Value Fair Value (Level 2) Balance Sheet Location Notional Value Fair Value (Level 2) Balance Sheet Location (In thousands) Japanese yen $ 235,397 $ 457 Other current assets $ 279,027 $ 2,745 Other current assets Korean won 76,415 (11) Accrued expenses 59,036 (97) Accrued expenses Philippine peso 9,009 (12) Accrued expenses 6,553 (20) Accrued expenses Singapore dollar 14,741 (50) Accrued expenses 11,506 20 Other current assets Taiwan dollar 38,850 28 Other current assets 37,914 89 Other current assets Total forward contracts $ 374,412 $ 412 $ 394,036 $ 2,737 For the three months ended March 31, 2024 and 2023, the derivatives resulted in a net loss of $27.5 million and $12.0 million, which were partially offset by the foreign currency gains associated with the underlying net liabilities.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
Fair Value Measurements	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The accounting framework for determining fair value includes a hierarchy for ranking the quality and reliability of the information used to measure fair value, which enables the reader of the financial statements to assess the inputs used to develop those measurements. The fair value hierarchy consists of three tiers as follows: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, model-based valuation techniques for which all significant assumptions are observable in the market or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and Level 3, defined as unobservable inputs that are not corroborated by market data. For our Level 2 short-term investments, we consider factors such as actual trade data, benchmark yields, broker/dealer quotes, and other similar data obtained from quoted market prices and independent pricing vendors to determine the fair value of these assets and liabilities. The fair values of cash, accounts receivable, trade accounts payable, capital expenditures payable and certain other current assets and accrued expenses approximate carrying values because of their short-term nature. The carrying value of certain other non-current assets and liabilities approximates fair value. Our assets and liabilities recorded at fair value on a recurring basis include restricted cash money market funds and short-term investments, including investments classified as cash equivalents. Cash equivalent money market funds and restricted cash money market funds are invested in U.S. money market funds and various U.S. and foreign bank operating and time deposit accounts, which are due on demand or carry a maturity date of less than three months when purchased. No restrictions have been imposed on us regarding withdrawal of balances with respect to our cash equivalents as a result of liquidity or other credit market issues affecting the money market funds we invest in or the counterparty financial institutions holding our deposits. Our derivative financial instruments are valued using quoted market prices for similar assets. Counterparties to these derivative contracts are highly rated financial institutions. We also measure certain assets and liabilities, including property, plant and equipment and goodwill, at fair value on a nonrecurring basis. We measure the fair value of our debt for disclosure purposes. The following table presents the fair value of our debt: March 31, 2024 December 31, 2023 Fair Value Carrying Value Fair Value Carrying Value (In thousands) Senior notes (Level 1) $ 528,008 $ 522,028 $ 531,778 $ 521,839 Revolving credit facilities and term loans (Level 2) 615,973 629,286 666,316 681,617 Total debt $ 1,143,981 $ 1,151,314 $ 1,198,094 $ 1,203,456 The estimated fair value of our senior notes is based primarily on quoted market prices reported on or near the respective balance sheet dates. The estimated fair value of our revolving credit facilities and term loans is calculated using a discounted cash flow analysis, which utilizes market-based assumptions, including forward interest rates adjusted for credit risk.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We generally warrant that our services will be performed in a professional and workmanlike manner and in compliance with our customers’ specifications. We accrue costs for known warranty issues. Historically, our warranty costs have been immaterial. Legal Proceedings We are involved in claims and legal proceedings and may become involved in other legal matters arising in the ordinary course of our business. We evaluate these claims and legal matters on a case-by-case basis to determine the impact, if any, on our business, liquidity, results of operations, financial condition or cash flows. Although the outcome of these matters is uncertain, we believe that the ultimate outcome of these claims and proceedings, individually and in the aggregate, will not have a material adverse impact to us. Our evaluation of the potential impact of these claims and legal proceedings on our business, liquidity, results of operations, financial condition or cash flows could change in the future. In accordance with the accounting guidance for loss contingencies, including legal proceedings, lawsuits, pending claims and other legal matters, we accrue for a loss contingency when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. We adjust our accruals from time to time as we receive additional information, but the loss we incur may be significantly greater than or less than the amount we have accrued. We disclose loss contingencies if we believe they are material and there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred. Lease Commitments As of March 31, 2024 we have entered into additional lease agreements that have not yet commenced of approximately $58 million.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss) Attributable to Parent	$ 58,897	$ 45,351

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Interim Financial Statements (P

Interim Financial Statements (Policies)	3 Months Ended
Interim Financial Statements (Policies)	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation.
Use of Estimates	Use of Estimates. The Consolidated Financial Statements have been prepared in conformity with U.S. GAAP, using management’s best estimates and judgments where appropriate. These estimates and judgments affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. The estimates and judgments will also affect the reported amounts for certain revenues and expenses during the reporting period. Actual results could differ materially from these estimates and judgments as a result of, for example, any worsening of the global business and economic environment.
Goodwill	Goodwill.
Recently Issued Standards	Recently Issued Standards. In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires disclosure of additional income tax information, primarily related to effective tax rate reconciliation and income taxes paid. ASU 2023-09 is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. Adoption of this ASU should be applied on a prospective basis, but retrospective application is permitted. We are currently evaluating the impact of this new standard on our financial statements, which is expected to result in enhanced disclosures.
Income Taxes	We monitor on an ongoing basis our ability to utilize our deferred tax assets and whether there is a need for a related valuation allowance. In evaluating our ability to recover our deferred tax assets in the jurisdictions from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies and recent results of operations. We maintain a valuation allowance on certain U.S. and foreign deferred tax assets. Such valuation allowances are released as the related tax benefits are realized or when sufficient evidence exists to conclude that it is more likely than not that the deferred tax assets will be realized.
Commitments and Contingencies	In accordance with the accounting guidance for loss contingencies, including legal proceedings, lawsuits, pending claims and other legal matters, we accrue for a loss contingency when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. We adjust our accruals from time to time as we receive additional information, but the loss we incur may be significantly greater than or less than the amount we have accrued. We disclose loss contingencies if we believe they are material and there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.

Net Sales by Product Group an_2

Net Sales by Product Group and End Market (Tables)	3 Months Ended
Net Sales by Product Group and End Market (Tables)	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Schedule of net sales by product group	The following table presents our net sales by product group: For the Three Months Ended March 31, 2024 2023 (In thousands) Advanced products (1) $ 1,069,709 $ 1,067,377 Mainstream products (2) 295,802 404,162 Total net sales $ 1,365,511 $ 1,471,539 (1) Advanced products include flip chip, memory and wafer-level processing and related test services. (2) Mainstream products include all other wirebond packaging and related test services. Net sales by end market consist of the following: For the Three Months Ended March 31, 2024 2023 Communications (smartphones, tablets) 47 % 45 % Automotive, industrial and other (ADAS, electrification, infotainment, safety) 22 % 26 % Computing (data center, infrastructure, PC/laptop, storage) 17 % 17 % Consumer (AR & gaming, connected home, home electronics, wearables) 14 % 12 % Total net sales 100 % 100 %

Other Income and Expense (Table

Other Income and Expense (Tables)	3 Months Ended
Other Income and Expense (Tables)	Mar. 31, 2024
Other Income and Expenses [Abstract]
Schedule of other (income) expense	Other income and expense consist of the following: For the Three Months Ended March 31, 2024 2023 (In thousands) Interest income $ (16,796) $ (10,433) Foreign currency loss (gain), net 1,545 6,763 Other, net (44) 118 Total other (income) expense, net $ (15,295) $ (3,552)

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
Earnings Per Share (Tables)	Mar. 31, 2024
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted earnings per share	The following table summarizes the computation of basic and diluted EPS: For the Three Months Ended March 31, 2024 2023 (In thousands, Net income attributable to Amkor common stockholders $ 58,897 $ 45,351 Weighted-average number of common shares outstanding - basic 246,008 245,330 Effect of dilutive securities: Share-based awards 1,606 1,757 Weighted-average number of common shares outstanding - diluted 247,614 247,087 Net income attributable to Amkor per common share: Basic $ 0.24 $ 0.18 Diluted 0.24 0.18
Schedule of potential shares of common stock excluded from diluted earnings per share	The following table summarizes the potential shares of common stock that were excluded from diluted EPS because the effect of including these potential shares was anti-dilutive: For the Three Months Ended March 31, 2024 2023 (In thousands) Share-based awards 11 —

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
Accumulated Other Comprehensive Income (Loss) (Tables)	Mar. 31, 2024
Equity [Abstract]
Schedule of changes in accumulated other comprehensive income (loss), net of tax	Changes in accumulated other comprehensive income (loss), net of tax, consist of the following: Unrealized Gains (Losses) on Available-for-Sale Debt Investments (1) Defined Benefit Pension (2) Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2023 $ 212 $ 15,905 $ 233 $ 16,350 Other comprehensive income (loss) before reclassifications (253) — (9,047) (9,300) Amounts reclassified from accumulated other comprehensive income (loss) (55) (85) — (140) Other comprehensive income (loss) (308) (85) (9,047) (9,440) Accumulated other comprehensive income (loss) at March 31, 2024 $ (96) $ 15,820 $ (8,814) $ 6,910 Unrealized Gains (Losses) on Available-for-Sale Debt Investments (1) Defined Benefit Pension (2) Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2022 $ (1,573) $ 14,220 $ 4,052 $ 16,699 Other comprehensive income (loss) before reclassifications 645 — (2,113) (1,468) Amounts reclassified from accumulated other comprehensive income (loss) (44) (97) — (141) Other comprehensive income (loss) 601 (97) (2,113) (1,609) Accumulated other comprehensive income (loss) at March 31, 2023 $ (972) $ 14,123 $ 1,939 $ 15,090 (1) Amounts reclassified out of accumulated other comprehensive income (loss) are included as other (income) expense, net (Note 3). (2) Amounts reclassified out of accumulated other comprehensive income (loss) are included as a component of net periodic pension cost (Note 12) or other (income) expense, net (Note 3).

Investments (Tables)

Investments (Tables)	3 Months Ended
Investments (Tables)	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of debt securities available-for-sale	The following table summarizes our cash equivalents and available-for-sale debt investments: March 31, 2024 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents Commercial paper $ 51,970 $ — $ — $ 51,970 $ — $ 51,970 Corporate bonds 1,657 — — 1,657 — 1,657 Money market funds 97,440 — — 97,440 97,440 — U.S. government bonds 16,936 — — 16,936 16,936 — Total cash equivalents (2) 168,003 — — 168,003 114,376 53,627 Short-term investments Asset-backed securities 62,076 99 (27) 62,148 — 62,148 Certificate of deposits 19,294 — — 19,294 19,294 — Commercial paper 45,383 — — 45,383 — 45,383 Corporate bonds 255,876 277 (301) 255,852 — 255,852 U.S. government agency bonds 4,729 — (4) 4,725 — 4,725 U.S. government bonds 62,212 — (142) 62,070 62,070 — Total short-term investments 449,570 376 (474) 449,472 81,364 368,108 Total $ 617,573 $ 376 $ (474) $ 617,475 $ 195,740 $ 421,735 December 31, 2023 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents Asset-backed securities $ 138 $ — $ — $ 138 $ — $ 138 Commercial paper 48,063 — — 48,063 — 48,063 Money market funds 60,719 — — 60,719 60,719 — U.S. government bonds 2,996 — — 2,996 2,996 — Total cash equivalents 111,916 — — 111,916 63,715 48,201 Short-term investments Asset-backed securities 65,340 170 (22) 65,488 — 65,488 Certificate of deposits 17,086 — — 17,086 17,086 — Commercial paper 56,273 — — 56,273 — 56,273 Corporate bonds 251,671 432 (299) 251,804 — 251,804 U.S. government agency bonds 13,200 — (9) 13,191 — 13,191 U.S. government bonds 65,881 13 (79) 65,815 65,815 — Total short-term investments 469,451 615 (409) 469,657 82,901 386,756 Total $ 581,367 $ 615 $ (409) $ 581,573 $ 146,616 $ 434,957 (1) All unrealized losses have been in a continuous loss position for less than 12 months. We do not intend to sell the investments in an unrealized loss position, and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost bases. (2) For three months ended March 31, 2024 and 2023, we sold cash equivalent investments for proceeds of $5.8 million and $13.0 million, respectively, and realized no gain or loss on such sales. The following table summarizes the contractual maturities of our cash equivalents and available-for-sale debt investments as of March 31, 2024 : Amortized Cost Fair Value (In thousands) Within 1 year $ 459,067 $ 458,887 After 1 year through 5 years 96,430 96,440 Asset-backed securities 62,076 62,148 Total $ 617,573 $ 617,475

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	3 Months Ended
Property, Plant and Equipment (Tables)	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Schedule of property, plant and equipment and depreciation expense	Property, plant and equipment consist of the following: March 31, 2024 December 31, 2023 (In thousands) Land $ 211,211 $ 212,722 Buildings and improvements 2,149,095 2,080,589 Machinery and equipment 7,104,414 7,022,614 Finance lease assets 224,983 209,506 Furniture, fixtures and other equipment 22,460 22,655 Software and computer equipment 206,633 200,362 Construction in progress 198,263 223,332 Total property, plant and equipment 10,117,059 9,971,780 Accumulated depreciation and amortization (6,749,625) (6,672,335) Total property, plant and equipment, net $ 3,367,434 $ 3,299,445 The following table summarizes our depreciation expense: For the Three Months Ended March 31, 2024 2023 (In thousands) Depreciation expense $ 144,787 $ 156,614

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
Accrued Expenses (Tables)	Mar. 31, 2024
Payables and Accruals [Abstract]
Schedule of accrued expenses	Accrued expenses consist of the following: March 31, 2024 December 31, 2023 (In thousands) Payroll and benefits $ 95,100 $ 115,604 Deferred revenue and customer advances 67,439 71,117 Short-term finance lease liabilities 52,734 57,761 Income taxes payable 30,471 35,215 Accrued severance plan obligations 7,518 7,906 Accrued interest 2,318 11,175 Other accrued expenses 54,396 59,636 Total accrued expenses $ 309,976 $ 358,414

Debt (Tables)

Debt (Tables)	3 Months Ended
Debt (Tables)	Mar. 31, 2024
Debt Disclosure [Abstract]
Schedule of short-term borrowings and long-term debt	Following is a summary of short-term borrowings and long-term debt: March 31, 2024 December 31, 2023 (In thousands) Debt of Amkor Technology, Inc.: Senior notes: 6.625% Senior notes, due September 2027 $ 525,000 $ 525,000 Debt of subsidiaries: Amkor Technology Korea, Inc.: Term loan, fixed rate at 1.85%, due April 2024 (1) — — Term loan, fixed rate at 2.12%, due December 2028 200,000 200,000 Amkor Technology Japan, Inc.: Short-term term loans, variable rate (2) 4,136 5,098 Term loan, fixed rate at 1.35%, due December 2024 28,246 40,414 Term loan, fixed rate at 1.20%, due December 2025 25,206 30,913 Term loan, fixed rate at 1.23%, due December 2026 47,605 55,729 Term loan, fixed rate at 1.59%, due December 2027 77,800 89,053 Term loan, fixed rate at 1.80%, due December 2028 109,845 124,078 Amkor Assembly & Test (Shanghai) Co., Ltd.: Term loans, SOFR plus 0.75%, weighted average of 6.06% as of March 31, 2024, due June 2025 37,000 37,000 Term loans, SOFR plus 0.75%, weighted average of 6.06% as of March 31, 2024, due 2025 57,000 57,500 Term loans, SOFR plus 0.95%, due December 2026 (3) 45,000 45,000 Other: Credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) (4) — — Senior secured revolving credit facility, applicable bank rate plus 1.75%, due March 2027 (Singapore) (5) — — 1,156,838 1,209,785 Less: Unamortized discount and deferred debt costs, net (5,524) (6,329) Less: Short-term borrowings and current portion of long-term debt (112,968) (131,624) Long-term debt $ 1,038,346 $ 1,071,832 (1) In April 2021, we entered into a ₩80.0 billion term loan agreement with the option to borrow and re-borrow the funds up to six times per year through April 2024. Principal is payable at maturity, and interest is payable monthly, at a fixed rate of 1.85%. As of March 31, 2024, ₩80.0 billion, or approximately $59 million, was available to be drawn. (2) We entered into various short-term term loans which mature semiannually. Principal and interest are payable in monthly installments. Interest as of March 31, 2024 is at an annual base rate equal to the Tokyo Interbank Offered Rate plus 0.18% to 0.20% (weighted average of 0.25% as of March 31, 2024). As of March 31, 2024, $2.9 million was available to be drawn. (3) In February 2024, Amkor Assembly & Test (Shanghai) Co. Ltd. amended the term loan due December 2026 to reduce the interest rate from SOFR plus 1.40% to SOFR plus 0.95% (weighted average of 6.27% as of March 31, 2024). This contractual amendment is treated as a modification with no recognized gain or loss. (4) In March 2022, Amkor Technology Taiwan Ltd. (“ATT”) amended an existing revolving credit facility to reduce availability from $36.0 million to $15.0 million. As of March 31, 2024, $15.0 million was available for future borrowings under such credit facility. (5)

Pension Plans (Tables)

Pension Plans (Tables)	3 Months Ended
Pension Plans (Tables)	Mar. 31, 2024
Retirement Benefits [Abstract]
Schedule of components of net periodic pension cost	The components of net periodic pension cost for these defined benefit pension plans are as follows: For the Three Months Ended March 31, 2024 2023 (In thousands) Service cost $ 3,484 $ 3,828 Interest cost 1,459 1,603 Expected return on plan assets (1,418) (1,311) Recognized actuarial gain (97) (98) Net periodic pension cost $ 3,428 $ 4,022
Schedule of defined contribution expense	The following table summarizes our defined contribution expense: For the Three Months Ended March 31, 2024 2023 (In thousands) Defined contribution expense $ 8,414 $ 8,796

Derivatives (Tables)

Derivatives (Tables)	3 Months Ended
Derivatives (Tables)	Mar. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of air value of derivative instruments in statement of financial position	As of March 31, 2024 and December 31, 2023, our foreign exchange forward contracts consisted of the following: March 31, 2024 December 31, 2023 Notional Value Fair Value (Level 2) Balance Sheet Location Notional Value Fair Value (Level 2) Balance Sheet Location (In thousands) Japanese yen $ 235,397 $ 457 Other current assets $ 279,027 $ 2,745 Other current assets Korean won 76,415 (11) Accrued expenses 59,036 (97) Accrued expenses Philippine peso 9,009 (12) Accrued expenses 6,553 (20) Accrued expenses Singapore dollar 14,741 (50) Accrued expenses 11,506 20 Other current assets Taiwan dollar 38,850 28 Other current assets 37,914 89 Other current assets Total forward contracts $ 374,412 $ 412 $ 394,036 $ 2,737

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
Fair Value Measurements (Tables)	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of fair value of financial instruments that are not recorded at fair value on recurring basis	The following table presents the fair value of our debt: March 31, 2024 December 31, 2023 Fair Value Carrying Value Fair Value Carrying Value (In thousands) Senior notes (Level 1) $ 528,008 $ 522,028 $ 531,778 $ 521,839 Revolving credit facilities and term loans (Level 2) 615,973 629,286 666,316 681,617 Total debt $ 1,143,981 $ 1,151,314 $ 1,198,094 $ 1,203,456

Interim Financial Statements (D

Interim Financial Statements (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($) installment $ / shares	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Long-term finance lease liabilities	$ 49,700		$ 47,800
Unbilled receivables	229,800		260,800
Contract liabilities	123,600		135,500
Deferred revenue and customer advances	67,439		$ 71,117
Revenue recognized	$ 18,900	$ 21,500
RSUs
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Award vesting installments \| installment	3
PSUs
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Award vesting period	3 years
EPS PSUs
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Percentage of total awards granted	50%
rTSR PSUs
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Award vesting period	3 years
Percentage of total awards granted	50%
Risk free interest rate	4.33%
Annualized average volatility rate	46.77%
Weighted average grant date fair value (in dollars per share) \| $ / shares	$ 27.07
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected timing of satisfaction, period	1 year
Minimum \| EPS PSUs
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Award vesting rights, percentage	0%
Minimum \| rTSR PSUs
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Award vesting rights, percentage	0%
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected timing of satisfaction, period	5 years
Maximum \| EPS PSUs
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Award vesting rights, percentage	225%
Maximum \| rTSR PSUs
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Award vesting rights, percentage	150%

Net Sales by Product Group an_3

Net Sales by Product Group and End Market - Product Group (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,365,511	$ 1,471,539
Advanced products
Disaggregation of Revenue [Line Items]
Total net sales	1,069,709	1,067,377
Mainstream products
Disaggregation of Revenue [Line Items]
Total net sales	$ 295,802	$ 404,162

Net Sales by Product Group an_4

Net Sales by Product Group and End Market - End Market (Details)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Total net sales (percentage)	100%	100%
Net sales \| Distribution Channel Concentration Risk \| Communications (smartphones, tablets)
Disaggregation of Revenue [Line Items]
Total net sales (percentage)	47%	45%
Net sales \| Distribution Channel Concentration Risk \| Automotive, industrial and other (ADAS, electrification, infotainment, safety)
Disaggregation of Revenue [Line Items]
Total net sales (percentage)	22%	26%
Net sales \| Distribution Channel Concentration Risk \| Computing (data center, infrastructure, PC/laptop, storage)
Disaggregation of Revenue [Line Items]
Total net sales (percentage)	17%	17%
Net sales \| Distribution Channel Concentration Risk \| Consumer (AR & gaming, connected home, home electronics, wearables)
Disaggregation of Revenue [Line Items]
Total net sales (percentage)	14%	12%

Other Income and Expense (Detai

Other Income and Expense (Details) - USD ($) $ in Thousands	3 Months Ended
Other Income and Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Other Income and Expenses [Abstract]
Interest income	$ (16,796)	$ (10,433)
Foreign currency loss (gain), net	1,545	6,763
Other, net	(44)	118
Total other (income) expense, net	$ (15,295)	$ (3,552)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income tax expense	$ 12,196	$ 10,864
Gross unrecognized tax benefits	$ 30,600		$ 31,500

Earnings Per Share - Calculatio

Earnings Per Share - Calculation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Net income attributable to Amkor common stockholders, basic	$ 58,897	$ 45,351
Net income attributable to Amkor common stockholders, diluted	$ 58,897	$ 45,351
Weighted-average number of common shares outstanding - basic (in shares)	246,008	245,330
Effect of dilutive securities:
Share-based awards (in shares)	1,606	1,757
Weighted-average number of common shares outstanding - diluted (in shares)	247,614	247,087
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.24	$ 0.18
Diluted (in dollars per share)	$ 0.24	$ 0.18

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Share-based awards (in shares)	11	0

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 3,995,035	$ 3,699,701
Other comprehensive income (loss) before reclassifications	(9,300)	(1,468)
Amounts reclassified from accumulated other comprehensive income (loss)	(140)	(141)
Total other comprehensive income (loss)	(9,440)	(1,609)
Balance at end of period	4,030,608	3,727,163
Unrealized Gains (Losses) on Available-for-Sale Debt Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	212	(1,573)
Other comprehensive income (loss) before reclassifications	(253)	645
Amounts reclassified from accumulated other comprehensive income (loss)	(55)	(44)
Total other comprehensive income (loss)	(308)	601
Balance at end of period	(96)	(972)
Defined Benefit Pension
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	15,905	14,220
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	(85)	(97)
Total other comprehensive income (loss)	(85)	(97)
Balance at end of period	15,820	14,123
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	233	4,052
Other comprehensive income (loss) before reclassifications	(9,047)	(2,113)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	(9,047)	(2,113)
Balance at end of period	(8,814)	1,939
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	16,350	16,699
Total other comprehensive income (loss)	(9,440)	(1,609)
Balance at end of period	$ 6,910	$ 15,090

Investments - Schedule of Cash

Investments - Schedule of Cash Equivalents, and Short term Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Total, Amortized Cost	$ 617,573		$ 581,367
Total, Gross Unrealized Gains	376		615
Total, Gross Unrealized Losses	(474)		(409)
Total Fair Value	617,475		581,573
Proceeds from sale of cash equivalent investments	5,800	$ 13,000
Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Amortized Cost	449,570		469,451
Short-term investments, Gross Unrealized Gains	376		615
Short-term investments, Gross Unrealized Losses	(474)		(409)
Short-term investments, Total Fair Value	449,472		469,657
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Amortized Cost	62,076		65,340
Short-term investments, Gross Unrealized Gains	99		170
Short-term investments, Gross Unrealized Losses	(27)		(22)
Short-term investments, Total Fair Value	62,148		65,488
Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Amortized Cost	19,294		17,086
Short-term investments, Gross Unrealized Gains	0		0
Short-term investments, Gross Unrealized Losses	0		0
Short-term investments, Total Fair Value	19,294		17,086
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Amortized Cost	45,383		56,273
Short-term investments, Gross Unrealized Gains	0		0
Short-term investments, Gross Unrealized Losses	0		0
Short-term investments, Total Fair Value	45,383		56,273
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Amortized Cost	255,876		251,671
Short-term investments, Gross Unrealized Gains	277		432
Short-term investments, Gross Unrealized Losses	(301)		(299)
Short-term investments, Total Fair Value	255,852		251,804
U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Amortized Cost	4,729		13,200
Short-term investments, Gross Unrealized Gains	0		0
Short-term investments, Gross Unrealized Losses	(4)		(9)
Short-term investments, Total Fair Value	4,725		13,191
U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Amortized Cost	62,212		65,881
Short-term investments, Gross Unrealized Gains	0		13
Short-term investments, Gross Unrealized Losses	(142)		(79)
Short-term investments, Total Fair Value	62,070		65,815
Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, Amortized Cost	168,003		111,916
Cash equivalents, Gross Unrealized Gains	0		0
Cash equivalents, Gross Unrealized Losses	0		0
Cash equivalent, Total Fair Value	168,003		111,916
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, Amortized Cost			138
Cash equivalents, Gross Unrealized Gains			0
Cash equivalents, Gross Unrealized Losses			0
Cash equivalent, Total Fair Value			138
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, Amortized Cost	51,970		48,063
Cash equivalents, Gross Unrealized Gains	0		0
Cash equivalents, Gross Unrealized Losses	0		0
Cash equivalent, Total Fair Value	51,970		48,063
Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, Amortized Cost	97,440		60,719
Cash equivalents, Gross Unrealized Gains	0		0
Cash equivalents, Gross Unrealized Losses	0		0
Cash equivalent, Total Fair Value	97,440		60,719
U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, Amortized Cost	16,936		2,996
Cash equivalents, Gross Unrealized Gains	0		0
Cash equivalents, Gross Unrealized Losses	0		0
Cash equivalent, Total Fair Value	16,936		2,996
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, Amortized Cost	1,657
Cash equivalents, Gross Unrealized Gains	0
Cash equivalents, Gross Unrealized Losses	0
Cash equivalent, Total Fair Value	1,657
Level 1
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	195,740		146,616
Level 1 \| Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	81,364		82,901
Level 1 \| Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	0		0
Level 1 \| Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	19,294		17,086
Level 1 \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	0		0
Level 1 \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	0		0
Level 1 \| U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	0		0
Level 1 \| U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	62,070		65,815
Level 1 \| Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	114,376		63,715
Level 1 \| Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value			0
Level 1 \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	0		0
Level 1 \| Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	97,440		60,719
Level 1 \| U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	16,936		2,996
Level 1 \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	0
Level 2
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	421,735		434,957
Level 2 \| Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	368,108		386,756
Level 2 \| Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	62,148		65,488
Level 2 \| Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	0		0
Level 2 \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	45,383		56,273
Level 2 \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	255,852		251,804
Level 2 \| U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	4,725		13,191
Level 2 \| U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, Total Fair Value	0		0
Level 2 \| Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	53,627		48,201
Level 2 \| Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value			138
Level 2 \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	51,970		48,063
Level 2 \| Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	0		0
Level 2 \| U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	0		$ 0
Level 2 \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, Total Fair Value	$ 1,657

Investments - Contractual Matur

Investments - Contractual Maturities of Cash Equivalents And Available-for-Sale Debt Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Within 1 year, Amortized Cost	$ 459,067
After 1 year through 5 years, Amortized Cost	96,430
Total, Amortized Cost	617,573	$ 581,367
Within 1 year, Fair Value	458,887
After 1 year through 5 years, Fair Value	96,440
Total Fair Value	617,475	$ 581,573
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Asset-backed securities, Amortized Cost	62,076
Asset-backed securities, Fair Value	$ 62,148

Investments - Narrative (Detail

Investments - Narrative (Details) - Level 1 - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost of held-to-maturity securities	$ 5.2	$ 5.2
Fair market value of held-to-maturity securities	$ 5.2	$ 5.2

Factoring of Accounts Receiva_2

Factoring of Accounts Receivable (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Total Factored
Factoring of Accounts Receivable [Line Items]
Accounts receivable sold	$ 24.4	$ 78
Discounts and Fees
Factoring of Accounts Receivable [Line Items]
Accounts receivable sold	$ 0	$ 0.2

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Finance lease assets	$ 224,983	$ 209,506
Total property, plant and equipment	10,117,059	9,971,780
Accumulated depreciation and amortization	(6,749,625)	(6,672,335)
Total property, plant and equipment, net	3,367,434	3,299,445
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	211,211	212,722
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	2,149,095	2,080,589
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	7,104,414	7,022,614
Furniture, fixtures and other equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	22,460	22,655
Software and computer equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	206,633	200,362
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 198,263	$ 223,332

Property, Plant and Equipment -

Property, Plant and Equipment - Schedule of Depreciation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 144,787	$ 156,614

Property, Plant and Equipment_3

Property, Plant and Equipment - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Jan. 01, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Net income	$ 58,897	$ 45,351
Diluted earnings per share (in dollars per share)	$ 0.24	$ 0.18
Test Equipment, Useful Lives
Property, Plant and Equipment [Line Items]
Reduction in depreciation expense	$ 15,000
Net income	$ 13,000
Diluted earnings per share (in dollars per share)	$ 0.05
Test Equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)			7 years	5 years

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Payroll and benefits	$ 95,100	$ 115,604
Deferred revenue and customer advances	67,439	71,117
Short-term finance lease liabilities	$ 52,734	$ 57,761
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Total accrued expenses	Total accrued expenses
Income taxes payable	$ 30,471	$ 35,215
Accrued severance plan obligations	7,518	7,906
Accrued interest	2,318	11,175
Other accrued expenses	54,396	59,636
Total accrued expenses	$ 309,976	$ 358,414

Debt (Details)

Debt (Details)		1 Months Ended	3 Months Ended	4 Months Ended
Debt (Details)	Dec. 31, 2023 USD ($)	Feb. 28, 2024	Mar. 31, 2024 USD ($)	Sep. 30, 2023	Mar. 31, 2024 KRW (₩)	Mar. 31, 2023	Mar. 31, 2022 USD ($)	Feb. 28, 2022 USD ($)	Apr. 30, 2021 KRW (₩) borrowing
Debt Instrument [Line Items]
Total debt	$ 1,209,785,000		$ 1,156,838,000
Less: Unamortized discount and deferred debt costs, net	(6,329,000)		(5,524,000)
Less: Short-term borrowings and current portion of long-term debt	(131,624,000)		(112,968,000)
Long-term debt	1,071,832,000		1,038,346,000
Collateralized debt			627,700,000
Asset Pledged as Collateral
Debt Instrument [Line Items]
Collateralized debt			319,000,000
Short-term term loans, variable rate \| Japan \| Subsidiary Term Loans
Debt Instrument [Line Items]
Total debt	5,098,000		4,136,000
Borrowing capacity available			$ 2,900,000
Short-term term loans, variable rate \| Japan \| Subsidiary Term Loans \| Weighted Average
Debt Instrument [Line Items]
Weighted average interest rate (as a percent)			0.25%		0.25%
Short-term term loans, variable rate \| Japan \| TIBOR \| Subsidiary Term Loans \| Minimum
Debt Instrument [Line Items]
Interest rate spread (as a percent)			0.18%
Short-term term loans, variable rate \| Japan \| TIBOR \| Subsidiary Term Loans \| Maximum
Debt Instrument [Line Items]
Interest rate spread (as a percent)			0.20%
Senior Notes \| 6.625% Senior notes, due September 2027
Debt Instrument [Line Items]
Interest rate (as a percent)			6.625%		6.625%
Total debt	525,000,000		$ 525,000,000
Subsidiary Term Loans \| Term loan, fixed rate at 1.85%, due April 2024 \| Korea
Debt Instrument [Line Items]
Interest rate (as a percent)			1.85%		1.85%
Total debt	0		$ 0
Face amount of debt \| ₩									₩ 80,000,000,000
Number of annual borrowings \| borrowing									6
Borrowing capacity available			$ 59,000,000		₩ 80,000,000,000
Subsidiary Term Loans \| Term loan, fixed rate at 2.12%, due December 2028 \| Korea
Debt Instrument [Line Items]
Interest rate (as a percent)			2.12%		2.12%
Total debt	200,000,000		$ 200,000,000
Subsidiary Term Loans \| Term loan, fixed rate at 1.35%, due December 2024 \| Japan
Debt Instrument [Line Items]
Interest rate (as a percent)			1.35%		1.35%
Total debt	40,414,000		$ 28,246,000
Subsidiary Term Loans \| Term loan, fixed rate at 1.20%, due December 2025 \| Japan
Debt Instrument [Line Items]
Interest rate (as a percent)			1.20%		1.20%
Total debt	30,913,000		$ 25,206,000
Subsidiary Term Loans \| Term loan, fixed rate at 1.23%, due December 2026 \| Japan
Debt Instrument [Line Items]
Interest rate (as a percent)			1.23%		1.23%
Total debt	55,729,000		$ 47,605,000
Subsidiary Term Loans \| Term loan, fixed rate at 1.59%, due December 2027 \| Japan
Debt Instrument [Line Items]
Interest rate (as a percent)			1.59%		1.59%
Total debt	89,053,000		$ 77,800,000
Subsidiary Term Loans \| Term loan, fixed rate at 1.80%, due December 2028 \| Japan
Debt Instrument [Line Items]
Interest rate (as a percent)			1.80%		1.80%
Total debt	124,078,000		$ 109,845,000
Subsidiary Term Loans \| Term loans, SOFR plus 0.75%, weighted average of $6.06% as of March 31, 2024, due June 2025 \| China
Debt Instrument [Line Items]
Total debt	37,000,000		$ 37,000,000
Subsidiary Term Loans \| Term loans, SOFR plus 0.75%, weighted average of $6.06% as of March 31, 2024, due June 2025 \| China \| SOFR
Debt Instrument [Line Items]
Interest rate spread (as a percent)				0.75%
Weighted average interest rate (as a percent)			6.06%		6.06%
Subsidiary Term Loans \| Term loans, SOFR plus 0.75%, weighted average of $6.06% as of March 31, 2024, due 2025 \| China
Debt Instrument [Line Items]
Total debt	57,500,000		$ 57,000,000
Subsidiary Term Loans \| Term loans, SOFR plus 0.75%, weighted average of $6.06% as of March 31, 2024, due 2025 \| China \| SOFR
Debt Instrument [Line Items]
Interest rate spread (as a percent)				0.75%
Weighted average interest rate (as a percent)			6.06%		6.06%
Subsidiary Term Loans \| Term loans, SOFR plus 0.95% December 2026 \| China
Debt Instrument [Line Items]
Total debt	$ 45,000,000		$ 45,000,000
Subsidiary Term Loans \| Term loans, SOFR plus 0.95% December 2026 \| China \| Weighted Average
Debt Instrument [Line Items]
Weighted average interest rate (as a percent)			6.27%		6.27%
Subsidiary Term Loans \| Term loans, SOFR plus 0.95% December 2026 \| China \| SOFR
Debt Instrument [Line Items]
Interest rate spread (as a percent)		0.95%
Subsidiary Term Loans \| Term Loans, SOFR Plus 1.40%, Due December 2026 \| China \| SOFR
Debt Instrument [Line Items]
Interest rate spread (as a percent)	1.40%
Line of Credit \| Credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) \| Revolving Credit Facility \| Taiwan
Debt Instrument [Line Items]
Total debt	$ 0		$ 0
Borrowing capacity available			15,000,000
Credit facility, borrowing capacity							$ 15,000,000	$ 36,000,000
Line of Credit \| $600.0 million senior secured revolving credit facility, applicable bank rate plus 1.75%, due March 2027 (Singapore) \| Revolving Credit Facility \| Singapore
Debt Instrument [Line Items]
Interest rate (as a percent)						1.75%
Total debt	$ 0		0
Borrowing capacity available			$ 600,000,000
Credit facility, borrowing capacity							600,000,000
Credit facility, base amount							$ 250,000,000
Credit facility percentage of variable borrowings							37.50%

Pension Plans - Components of N

Pension Plans - Components of Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Retirement Benefits [Abstract]
Service cost	$ 3,484	$ 3,828
Interest cost	1,459	1,603
Expected return on plan assets	(1,418)	(1,311)
Recognized actuarial gain	(97)	(98)
Net periodic pension cost	$ 3,428	$ 4,022

Pension Plans - Summary of Defi

Pension Plans - Summary of Defined Contribution Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Retirement Benefits [Abstract]
Defined contribution expense	$ 8,414	$ 8,796

Derivatives (Details)

Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended
Derivatives (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accrued Liabilities, Current		Accrued Liabilities, Current
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets, Current		Other Assets, Current
Net loss on derivatives	$ 27,500	$ 12,000
Foreign Exchange Forward
Derivatives, Fair Value [Line Items]
Notional Value	374,412		$ 394,036
Foreign Exchange Forward \| Level 2
Derivatives, Fair Value [Line Items]
Derivative, fair value, net	412		2,737
Foreign Exchange Forward \| Japanese yen
Derivatives, Fair Value [Line Items]
Notional Value	235,397		279,027
Foreign Exchange Forward \| Japanese yen \| Level 2
Derivatives, Fair Value [Line Items]
Derivative asset, fair value			2,745
Derivative liability, fair value	457
Foreign Exchange Forward \| Korean won
Derivatives, Fair Value [Line Items]
Notional Value	76,415		59,036
Foreign Exchange Forward \| Korean won \| Level 2
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	(11)
Derivative liability, fair value			(97)
Foreign Exchange Forward \| Philippine peso
Derivatives, Fair Value [Line Items]
Notional Value	9,009		6,553
Foreign Exchange Forward \| Philippine peso \| Level 2
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	(12)		(20)
Foreign Exchange Forward \| Singapore dollar
Derivatives, Fair Value [Line Items]
Notional Value	14,741		11,506
Foreign Exchange Forward \| Singapore dollar \| Level 2
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	(50)		20
Foreign Exchange Forward \| Taiwan dollar
Derivatives, Fair Value [Line Items]
Notional Value	38,850		37,914
Foreign Exchange Forward \| Taiwan dollar \| Level 2
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	$ 28		$ 89

Fair Value Measurements (Debt)

Fair Value Measurements (Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	$ 1,143,981	$ 1,198,094
Fair Value \| Senior notes (Level 1) \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	528,008	531,778
Fair Value \| Revolving credit facilities and term loans (Level 2) \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	615,973	666,316
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	1,151,314	1,203,456
Carrying Value \| Senior notes (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	522,028	521,839
Carrying Value \| Revolving credit facilities and term loans (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	$ 629,286	$ 681,617

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	Mar. 31, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Amount of leases not yet commenced	$ 58