Arthur J. Gallagher & Co. (AJG) 10-K10 Feb 232022 FY Annual reportFinancial data

Company Profile

Cover Page

Cover Page - USD ($)	12 Months Ended
Cover Page - USD ($)	Dec. 31, 2022	Jan. 31, 2023	Jun. 30, 2022
Cover [Abstract]
Amendment Flag	false
Document Type	10-K
Document Fiscal Year Focus	2022
Entity Interactive Data Current	Yes
Document Fiscal Period Focus	FY
Document Annual Report	true
Entity Central Index Key	0000354190
Document Transition Report	false
Current Fiscal Year End Date	--12-31
Document Period End Date	Dec. 31, 2022
Entity Registrant Name	ARTHUR J. GALLAGHER & CO.
Entity File Number	1-09761
Entity Tax Identification Number	36-2151613
Entity Incorporation, State or Country Code	DE
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Address, Address Line One	2850 Golf Road
Entity Address, City or Town	Rolling Meadows
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60008-4050
City Area Code	630
Local Phone Number	773-3800
Trading Symbol	AJG
Security Exchange Name	NYSE
Title of 12(b) Security	Common Stock, par value $1.00 per share
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
ICFR Auditor Attestation Flag	true
Entity Public Float			$ 29,577,349,000
Entity Common Stock, Shares Outstanding		212,094,000
Auditor Name	Ernst & Young LLP
Auditor Location	Chicago, Illinois
Auditor Firm ID	42
Documents Incorporated by Reference	Documents incorporated by reference: Portions of Arthur J. Gallagher & Co.’s definitive 2023 Proxy Statement are incorporated by reference into this Form 10‑K in response to Part III to the extent described herein.

Consolidated Statement of Earni

Consolidated Statement of Earnings - USD ($) $ in Millions	12 Months Ended
Consolidated Statement of Earnings - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues before reimbursements	$ 8,420.1	$ 8,076.4	$ 6,851.9
Reimbursements	130.5	133	151.7
Total revenues	8,550.6	8,209.4	7,003.6
Compensation	4,799.8	3,927.5	3,466.5
Operating	1,330.9	1,072.4	906.5
Reimbursements	130.5	133	151.7
Cost of revenues from clean coal activities	22.9	1,173.2	882.1
Interest	256.9	226.1	196.4
Loss on extinguishment of debt		16.2
Depreciation	144.7	151.2	145.1
Amortization	454.9	415.1	417.3
Change in estimated acquisition earnout payables	83	119.6	(32.9)
Total expenses	7,223.6	7,234.3	6,132.7
Earnings before income taxes	1,327	975.1	870.9
Provision for income taxes	211	20.1	12.8
Net earnings	1,116	955	858.1
Net earnings attributable to noncontrolling interests	1.8	48.2	39.3
Net earnings attributable to controlling interests	$ 1,114.2	$ 906.8	$ 818.8
Basic net earnings per share	$ 5.30	$ 4.47	$ 4.29
Diluted net earnings per share	5.19	4.37	4.20
Dividends declared per common share	$ 2.04	$ 1.92	$ 1.80
Commissions [Member]
Revenues before reimbursements	$ 5,187.4	$ 4,132.3	$ 3,591.9
Broker Fees [Member]
Revenues before reimbursements	2,567.7	2,264.1	1,957.9
Supplemental Revenue [Member]
Revenues before reimbursements	284.7	248.7	221.9
Contingent Revenue [Member]
Revenues before reimbursements	207.3	188	147
Investment Income [Member]
Revenues before reimbursements	136.3	83.1	75.9
Net Gains (Losses) on Divestitures [Member]
Revenues before reimbursements	13	18.9	(5.8)
Clean Coal Activities [Member]
Revenues before reimbursements	23	1,140.8	863.5
Other income (Losses) [Member]
Revenues before reimbursements	$ 0.7	$ 0.5	$ (0.4)

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Earnings - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net earnings	$ 1,116	$ 955	$ 858.1
Change in pension liability, net of taxes	(12.3)	19	0.4
Foreign currency translation, net of taxes	(511.8)	(122.3)	183.7
Change in fair value of derivative instruments, net of taxes	109.8	20.8	(68.1)
Comprehensive earnings	701.7	872.5	974.1
Comprehensive earnings attributable to noncontrolling interests	1.6	49.5	39.7
Comprehensive earnings attributable to controlling interests	$ 700.1	$ 823	$ 934.4

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Cash and cash equivalents	$ 342.3	$ 402.6
Restricted cash	4,621.9	4,063.7
Premiums and fees receivable	16,408.9	11,753.1
Other current assets	1,461.5	1,451
Total current assets	22,834.6	17,670.4
Fixed assets - net	576.2	500.8
Deferred income taxes	1,299	1,228.5
Other noncurrent assets	989.8	966.5
Right-of-use assets	346.7	358.6
Goodwill - net	9,489.4	8,666.2
Amortizable intangible assets - net	3,372.1	3,954
Total assets	38,907.8	33,345
Premiums payable to underwriting enterprises	18,698.2	13,845.6
Accrued compensation and other accrued liabilities	2,091.2	1,895.1
Deferred revenue - current	546.7	520.9
Premium financing debt	241.9	228.4
Corporate related borrowings - current	310	245
Total current liabilities	21,888	16,735
Corporate related borrowings - noncurrent	5,562.8	5,810.2
Deferred revenue - noncurrent	62.6	58.7
Lease liabilities - noncurrent	300.4	309.3
Other noncurrent liabilities	1,903.8	1,871.7
Total liabilities	29,717.6	24,784.9
Stockholders' equity:
Common stock - authorized 400.0 shares; issued and outstanding 211.9 shares in 2022 and 208.5 shares in 2021	211.9	208.5
Capital in excess of par value	6,509.9	6,143.7
Retained earnings	3,562.2	2,882.3
Accumulated other comprehensive loss	(1,140.4)	(726.1)
Stockholders' equity attributable to controlling interests	9,143.6	8,508.4
Stockholders' equity attributable to noncontrolling interests	46.6	51.7
Total stockholders' equity	9,190.2	8,560.1
Total liabilities and stockholders' equity	$ 38,907.8	$ 33,345

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - shares	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Common stock - authorized shares	400,000,000	400,000,000
Common stock - issued shares	211,900,000	208,500,000
Common stock - outstanding shares	211,900,000	208,500,000

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net earnings	$ 1,116	$ 955	$ 858.1
Adjustments to reconcile net earnings to net cash provided by operating activities:
Net (gain) loss on investments and other	(11)	(17)	6.3
Loss on extinguishment of debt		9.7
Depreciation and amortization	599.6	566.3	562.4
Change in estimated acquisition earnout payables	83	119.6	(32.9)
Amortization of deferred compensation and restricted stock	85.4	68.9	60.9
Stock-based and other noncash compensation expense	24.4	13.4	13.6
Payments on acquisition earnouts in excess of original estimates	(81.7)	(29.6)	(14.5)
Provision for deferred income taxes	(209)	(184)	(162)
Effect of changes in foreign exchange rate	(34)	2.3	2.9
Net change in premium and fees receivable	(4,789.3)	132.9	(796.5)
Net change in deferred revenue	29.3	23.1	18.5
Net change in premiums payable to underwriting enterprises	5,084.2	35.5	1,154.2
Net change in other current assets	(47.1)	(136.8)	(22.5)
Net change in accrued compensation and other accrued liabilities	215.3	222.3	91.8
Net change in income taxes payable	49.9	(123.8)	51.8
Net change in other noncurrent assets and liabilities	10.4	46.3	15
Net cash provided by operating activities	2,125.4	1,704.1	1,807.1
Cash flows from investing activities:
Capital expenditures	(182.7)	(128.6)	(99.3)
Cash paid for acquisitions, net of cash and restricted cash acquired	(764.9)	(3,250.9)	(324.3)
Net proceeds from sales of operations/books of business	11	15.7	8.2
Net funding of investment transactions	1	(1.1)	(1.4)
Net funding of premium finance loans	(69.2)	(66.8)	(54.6)
Net cash used by investing activities	(1,004.8)	(3,431.7)	(471.4)
Cash flows from financing activities:
Payments on acquisition earnouts	(106.5)	(137.3)	(38.8)
Proceeds from issuance of common stock	123.1	1,546.7	111.9
Payments to noncontrolling interests	(3.6)	(39.1)	(84.4)
Dividends paid	(429.5)	(392)	(347.4)
Net borrowings on premium financing debt facility	25.3	37	16
Borrowings on line of credit facility	2,570	1,280	2,630
Repayments on line of credit facility	(2,555)	(1,235)	(3,150)
Net borrowings of corporate related long-term debt	(201.5)	1,677	424.9
Debt acquisition costs	2.2	(21.3)	(1.3)
Settlements on terminated interest rate swaps	52.7	(31.9)	(66)
Net cash (used) provided by financing activities	(522.8)	2,684.1	(505.1)
Effect of changes in foreign exchange rates on cash, cash equivalents and restricted cash	(99.9)	(64.5)	119.8
Net increase in cash, cash equivalents and restricted cash	497.9	892	950.4
Cash, cash equivalents and restricted cash at beginning of year	4,466.3	3,574.3	2,623.9
Cash, cash equivalents and restricted cash at end of year	$ 4,964.2	$ 4,466.3	$ 3,574.3

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]
Beginning balance at Dec. 31, 2019	$ 5,215.5	$ 188.1	$ 3,825.7	$ 1,901.3	$ (759.6)	$ 60
Beginning balance (in shares) at Dec. 31, 2019		188.1
Net earnings	858.1			818.8		39.3
Net purchase of subsidiary shares from noncontrolling interests	(6.4)					(6.4)
Dividends paid to noncontrolling interests	(46.8)					(46.8)
Net change in pension asset/liability, net of taxes	0.4				0.4
Foreign currency translation	184.1				183.7	0.4
Change in fair value of derivative instruments, net of taxes	(68.1)				(68.1)
Compensation expense related to stock option plan grants	13.6		13.6
Common stock issued in: purchase transactions	309.1	$ 3	306.1
Common stock issued in: purchase transactions (in shares)		3
Stock option plans	77.7	$ 1.8	75.9
Stock option plans (in shares)		1.8
Employee stock purchase plan	34.2	$ 0.5	33.7
Employee stock purchase plan (in shares)		0.5
Deferred compensation and restricted stock	9.7	$ 0.3	9.4
Deferred compensation and restricted (in shares)		0.3
Cash dividends declared on common stock	(348.4)			(348.4)
Ending balance at Dec. 31, 2020	6,232.7	$ 193.7	4,264.4	2,371.7	(643.6)	46.5
Ending balance (in shares) at Dec. 31, 2020		193.7
Net earnings	955			906.8		48.2
Net purchase of subsidiary shares from noncontrolling interests	(6)					(6)
Dividends paid to noncontrolling interests	(38.3)					(38.3)
Net change in pension asset/liability, net of taxes	19				19
Foreign currency translation	(121)				(122.3)	1.3
Change in fair value of derivative instruments, net of taxes	20.8				20.8
Compensation expense related to stock option plan grants	17.5		17.5
Common stock issued in: purchase transactions	251.3	$ 1.7	249.6
Common stock issued in: purchase transactions (in shares)		1.7
Stock option plans	$ 67.6	$ 1.4	66.2
Stock option plans (in shares)	1.4	1.4
Employee stock purchase plan	$ 41.2	$ 0.4	40.8
Employee stock purchase plan (in shares)		0.4
Shares issued to benefit plans	71.4	$ 0.6	70.8
Shares issued to benefit plans (in shares)		0.6
Deferred compensation and restricted stock	6.9	$ 0.4	6.5
Deferred compensation and restricted (in shares)		0.4
Stock issuance from public offering	1,437.9	$ 10.3	1,427.6
Stock issuance from public offering (in shares)		10.3
Other compensation expense	0.3		0.3
Cash dividends declared on common stock	(396.2)			(396.2)
Ending balance at Dec. 31, 2021	$ 8,560.1	$ 208.5	6,143.7	2,882.3	(726.1)	51.7
Ending balance (in shares) at Dec. 31, 2021	208.5	208.5
Net earnings	$ 1,116			1,114.2		1.8
Net purchase of subsidiary shares from noncontrolling interests	(3.2)					(3.2)
Dividends paid to noncontrolling interests	(3.5)					(3.5)
Net change in pension asset/liability, net of taxes	(12.3)				(12.3)
Foreign currency translation	(512)				(511.8)	(0.2)
Change in fair value of derivative instruments, net of taxes	109.8				109.8
Compensation expense related to stock option plan grants	27.9		27.9
Common stock issued in: purchase transactions	165.5	$ 0.9	164.6
Common stock issued in: purchase transactions (in shares)		0.9
Stock option plans	$ 76.1	$ 1.4	74.7
Stock option plans (in shares)	1.4	1.4
Employee stock purchase plan	$ 47.6	$ 0.3	47.3
Employee stock purchase plan (in shares)		0.3
Shares issued to benefit plans	74.4	$ 0.5	73.9
Shares issued to benefit plans (in shares)		0.5
Deferred compensation and restricted stock	(21.9)	$ 0.3	(22.2)
Deferred compensation and restricted (in shares)		0.3
Cash dividends declared on common stock	(434.3)			(434.3)
Ending balance at Dec. 31, 2022	$ 9,190.2	$ 211.9	$ 6,509.9	$ 3,562.2	$ (1,140.4)	$ 46.6
Ending balance (in shares) at Dec. 31, 2022	211.9	211.9

Consolidated Statement of Sto_2

Consolidated Statement of Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Stockholders' Equity [Abstract]
Tax effect on net change in pension asset/liability	$ (3)	$ 4.6	$ 0.1
Net change in fair value of derivative instruments, tax	$ 39.3	$ 7.4	$ (22.4)

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies Terms Used in Notes to Consolidated Financial Statements ASC - Accounting Standards Codification. ASU - Accounting Standards Update. FASB - The Financial Accounting Standards Board. GAAP - United States (U.S.) generally accepted accounting principles. IRC - Internal Revenue Code. IRS - Internal Revenue Service. Topic 606 - ASU No. 2014-09, Revenue from Contracts with Customers. Underwriting enterprises - Insurance companies, reinsurance companies and various other forms of risk-taking entities, including intermediaries of underwriting enterprises. VIE - Variable interest entity. Nature of Operations Arthur J. Gallagher & Co. and its subsidiaries, collectively referred to herein as we, our, us or the company, provide insurance brokerage, consulting and third party claims settlement and administration services to both domestic and international entities. We have three reportable segments: brokerage, risk management and corporate. Our brokers, agents and administrators act as intermediaries between underwriting enterprises and our clients. Our brokerage segment operations provide brokerage and consulting services to companies and entities of all types, including commercial, not-for-profit, public entities, and, to a lesser extent, individuals, in the areas of insurance and reinsurance placements, risk of loss management and management of employer sponsored benefit programs. Our risk management segment operations provide contract claim settlement, claim administration, loss control services and risk management consulting for commercial, not‑for‑profit, captive and public entities, and various other organizations that choose to self-insure property/casualty coverages or choose to use a third-party claims management organization rather than the claim services provided by underwriting enterprises. The corporate segment reports the financial information related to our debt and other corporate costs, legacy clean energy investments, external acquisition‑related expenses and the impact of foreign currency translation. Legacy clean energy investments consist of our investments in limited liability companies that own or have owned 35 commercial clean coal production facilities that produced refined coal using Chem-Mod LLC’s proprietary technologies. We believe these operations produced refined coal that qualifies for tax credits under IRC Section 45. We do not assume underwriting risk on a net basis, other than with respect to de minimis amounts necessary to provide minimum or regulatory capital insurance to organize captives, pools, specialized underwriters or risk-retention groups. Rather, capital necessary for covering losses is provided by underwriting enterprises. Investment income and other revenues are primarily generated from our premium financing operations, our invested cash and restricted cash we hold on behalf of our clients, as well as clean energy investments. In addition, our share of the net earnings related to partially owned entities that are accounted for using the equity method is included in investment income. Arthur J. Gallagher & Co., a global insurance brokerage, risk management and consulting services firm, is headquartered in Rolling Meadows, Illinois. Gallagher provides these services in approximately 130 countries around the world through its owned operations and a network of correspondent brokers and consultants. Basis of Presentation The accompanying consolidated financial statements include our accounts and all of our majority-owned subsidiaries ( 50 % or greater ownership). Substantially all of our investments in partially owned entities in which our ownership is less than 50 % are accounted for using the equity method based on the legal form of our ownership interest and the applicable ownership percentage of the entity. However, in situations where a less than 50 %-owned investment has been determined to be a VIE and we are deemed to be the primary beneficiary in accordance with the variable interest model of consolidation, we will consolidate the investment into our consolidated financial statements. For partially owned entities accounted for using the equity method, our share of the net earnings of these entities is included in consolidated net earnings. All material intercompany accounts and transactions have been eliminated in consolidation. In the preparation of our consolidated financial statements as of December 31, 2022 , management evaluated all material subsequent events or transactions that occurred after the balance sheet date through the date on which the financial statements were issued for potential recognition and/or disclosure in the notes therein. Use of Estimates The preparation of our consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. These accounting principles require us to make estimates and assumptions that affect the reported amounts of assets and liabilities and revenues and expenses, and the disclosure of contingent assets and liabilities at the date of our consolidated financial statements. We periodically evaluate our estimates and assumptions, including those relating to the valuation of goodwill and other intangible assets, right-of-use assets, investments (including our IRC Section 45 investments), income taxes, revenue recognition, deferred costs, stock-based compensation, claims handling obligations, retirement plans, litigation and contingencies. We base our estimates on historical experience and various assumptions that we believe to be reasonable based on specific circumstances. Such estimates and assumptions could change in the future as more information becomes known, which could impact the amounts reported and disclosed herein. Revenue Recognition Our revenues are derived from commissions and fees as primarily specified in a written contract, or unwritten business understanding, with our clients or underwriting enterprises. We also recognize investment income over time from our invested assets and invested assets we hold on behalf of our clients or underwriting enterprises. BROKERAGE SEGMENT Our brokerage segment generates revenues by: (i) Identifying, negotiating and placing all forms of insurance or reinsurance coverage, as well as providing risk-shifting, risk-sharing and risk-mitigation consulting services, principally related to property/casualty, life, health, welfare and disability insurance. We also provide these services through, or in conjunction with, other unrelated agents and brokers, consultants and management advisors; (ii) Acting as an agent or broker for multiple underwriting enterprises by providing services such as sales, marketing, selecting, negotiating, underwriting, servicing and placing insurance coverage on their behalf; (iii) Providing consulting services related to health and welfare benefits, voluntary benefits, executive benefits, compensation, retirement planning, institutional investment and fiduciary, actuarial, compliance, private insurance exchange, human resource technology, communications and benefits administration; and (iv) Providing management and administrative services to captives, pools, risk-retention groups, healthcare exchanges, small underwriting enterprises, such as accounting, claims and loss processing assistance, feasibility studies, actuarial studies, data analytics and other administrative services. The vast majority of our brokerage contracts and service understandings are for a period of one year or less . Commissions and fees The primary source of revenues for our brokerage services is commissions from underwriting enterprises, based on a percentage of premiums paid by our clients, or fees received from clients based on an agreed level of service usually in lieu of commissions. These commissions and fees revenues are substantially recognized at a point in time on the effective date of the associated policies when control of the policy transfers to the client, as well as deferring certain revenues to reflect delivery of services over the contract period. Commissions are fixed at the contract effective date and generally are based on a percentage of premiums for insurance coverage or employee headcount for employer sponsored benefit plans. Commissions depend upon a large number of factors, including the type of risk being placed, the particular underwriting enterprise’s demand, the expected loss experience of the particular risk of coverage, and historical benchmarks surrounding the level of effort necessary for us to place and service the insurance contract. Rather than being tied to the amount of premiums, fees are most often based on an expected level of effort to provide our services. Whether we are paid a commission or a fee, the vast majority of our services are associated with the placement of an insurance (or insurance-like) contract. Accordingly, we recognize approximately 80 % of our commission and fee revenues on the effective date of the underlying insurance contract. The amount of revenue we recognize is based on our costs to provide our services up and through that effective date, including an appropriate estimate of our profit margin on a portfolio basis (a practical expedient as defined in Topic 606). Based on the proportion of additional services we provide in each period after the effective date of the insurance contract, including an appropriate estimate of our profit margin, we recognize approximately 15 % of our commission and fee revenues in the first three months, and the remaining 5 % thereafter. These periods may be different than the underlying premium payment patterns of the insurance contracts, but the vast majority of our services are fully provided within one year of the insurance contract effective date. For consulting and advisory services, we recognize our revenue in the period in which we provide the service or advice. For management and administrative services, our revenue is recognized ratably over the contract period consistent with the performance of our obligations, mostly over an annual term. Supplemental revenues Certain underwriting enterprises may pay us additional revenues for the volume of premium placed with them and for insights into our sales pipeline, our sales capabilities or our risk selection knowledge. These amounts are in excess of the commission and fee revenues discussed above, and not all business we place with underwriting enterprises is eligible for supplemental revenues. Unlike contingent revenues, discussed below, these revenues are primarily a fixed amount or fixed percentage of premium of the underlying eligible insurance contracts. For supplemental revenue contracts based on a fixed percentage of premium, our obligation to the underwriting enterprise is substantially completed upon the effective date of the underlying insurance contract and revenue is fully earned at that time. For supplemental revenue contracts based on a fixed amount, revenue is recognized ratably over the contract period consistent with the performance of our obligations, almost always over an annual term. We receive these revenues on a quarterly or annual basis. Contingent revenues Certain underwriting enterprises may pay us additional revenues for our sales capabilities, our risk selection knowledge, or our administrative efficiencies. These amounts are in excess of the commission or fee revenues discussed above, and not all business we place with participating underwriting enterprises is eligible for contingent revenues. Unlike supplemental revenues, also discussed above, these revenues are variable, generally based on growth, the loss experience of the underlying insurance contracts, and/or our efficiency in processing the business. We generally operate under calendar year contracts, but we do not receive these revenues from the underwriting enterprises until the following calendar year, generally in the first and second quarters, after verification of the performance indicators outlined in the contracts. Accordingly, during each reporting period, we must make our best estimate of amounts we have earned using historical averages and other factors to project such revenues. We base our estimates each period on a contract-by-contract basis where available. In certain cases, it is impractical to assess a very large number of smaller contingent revenue contracts, so we use a historical portfolio estimate in aggregate (a practical expedient as defined in Topic 606). Because our expectation of the ultimate contingent revenue amounts to be earned can vary from period to period, especially in contracts sensitive to loss ratios, our estimates might change significantly from quarter to quarter. For example, in circumstances where our revenues are dependent on a full calendar year loss ratio, adverse loss experience in the fourth quarter could not only negate revenue earnings in the fourth quarter, but also trigger the need to reverse revenues previously recognized during the prior quarters. Variable consideration is recognized when we conclude, based on all the facts and information available at the reporting date, that it is probable that a significant revenue reversal will not occur in future periods. Sub-brokerage costs Sub-brokerage costs are excluded from our gross revenues in our determination of total revenues. Sub-brokerage cost represents commissions paid to sub-brokers related to the placement of certain business by our brokerage segment operations. We recognize this contra revenue in the same manner as the commission revenue to which it relates. RISK MANAGEMENT SEGMENT Revenues for our risk management segment are comprised of fees generally negotiated (i) on a per-claim or per-service basis, (ii) on a cost‑plus basis, or (iii) as performance-based fees. We also provide risk management consulting services that are recognized as the services are delivered. Per-claim or per-service fees Where we operate under a contract with our fee established on a per-claim or per-service basis, our obligation is to process claims for a term specified within the contract. Because it is impractical to recognize our revenues on an individual claim-by-claim basis, we recognize revenue plus an appropriate estimate of our profit margin on a portfolio basis by grouping claims with similar characteristics (a practical expedient as defined in Topic 606). We apply actuarially-determined, historical-based patterns to determine our future service obligations, without applying a present value discount. Cost-plus fees Where we provide services and generate revenues on a cost-plus basis, we recognize revenue over the contract period consistent with the performance of our obligations. Performance-based fees Certain clients pay us additional fee revenues for our efficiency in managing claims or on the basis of claim outcome effectiveness. These amounts are in excess of the fee revenues discussed above. These revenues are variable, generally based on performance metrics set forth in the underlying contracts. We generally operate under multi-year contracts with fiscal year measurement periods. We do not receive these fees, if earned, until the following year after verification of the performance metrics outlined in the contracts. Each period we base our estimates on a contract-by-contract basis. We must make our best estimate of amounts we have earned using historical averages and other factors to project such revenues. Variable consideration is recognized when we conclude that it is probable that a significant revenue reversal will not occur in future periods. Reimbursements Reimbursements represent amounts received from clients reimbursing us for certain third-party costs associated with providing our claims management services. In certain service partner relationships, we are considered a principal because we direct the third party, control the specified service and combine the services provided into an integrated solution. Given this principal relationship, we are required to recognize revenue gross and service partner vendor fees in the operating expense in our consolidated statement of earnings. Deferred Costs We incur costs to provide brokerage and risk management services. Those costs are either (i) costs to obtain a contract or (ii) costs to fulfill such contract, or (iii) all other costs. (i) Costs to obtain - we incur costs to obtain a contract with a client. Those costs would not have been incurred if the contract had not been obtained. Almost all of our costs to obtain are incurred prior to, or on, the effective date of the contract and consist primarily of incentive compensation we pay to our production employees. Our costs to obtain are expensed as incurred as described in Note 4 to these consolidated financial statements. (ii) Costs to fulfill - we incur costs to fulfill a contract (or anticipated contract) with a client. Those costs are incurred prior to the effective date of the contract and relate to fulfilling our primary placement obligations to our clients. Our costs to fulfill prior to the effective date are capitalized and amortized on the effective date. These fulfillment activities include collecting underwriting information from our client, assessing their insurance needs and negotiating their placement with one or more underwriting enterprises. The majority of costs that we incur relate to compensation and benefits of our client service employees. Costs incurred during preplacement activities are expected to be recovered in the future. If the capitalized costs are no longer deemed to be recoverable, then they would be expensed. (iii) Other costs that are not costs to obtain or fulfill are expensed as incurred. Examples include other operating costs such as rent, utilities, management costs, overhead costs, legal and other professional fees, technology costs, insurance related costs, communication and advertising, and travel and entertainment. Depreciation, amortization and change in estimated acquisition earnout payable are expensed as incurred. Investment Income Investment income primarily includes interest and dividend income (including interest income from our premium financing operations), which is accrued as it is earned. Net gains on divestitures represent one-time gains related to sales of brokerage related businesses, which are primarily recognized on a cash received basis. Revenues from clean coal activities include revenues from consolidated clean coal production plants, royalty income from clean coal licenses and income (loss) related to unconsolidated clean coal production plants, all of which are recognized as earned. Revenues from consolidated clean coal production plants represent sales of refined coal. Royalty income from clean coal licenses represents fee income related to the use of clean coal technologies. Income (loss) from unconsolidated clean coal production plants includes losses related to our equity portion of the pretax results of the clean coal production plants. Earnings per Share Basic net earnings per share is computed by dividing net earnings by the weighted average number of common shares outstanding during the reporting period. Diluted net earnings per share is computed by dividing net earnings by the weighted average number of common and common equivalent shares outstanding during the reporting period. Common equivalent shares include incremental shares from dilutive stock options, which are calculated from the date of grant under the treasury stock method using the average market price for the period. Cash and Cash Equivalents Short-term investments, consisting principally of cash and money market accounts that have average maturities of 90 days or less, are considered cash equivalents. Restricted Cash In our capacity as an insurance broker, we collect premiums from insureds and, after deducting our commissions and/or fees, remit these premiums to underwriting enterprises. We hold unremitted insurance premiums in a fiduciary capacity until we disburse them, and the use of such funds is restricted by laws in certain states and foreign jurisdictions in which our subsidiaries operate. Various state and foreign agencies regulate insurance brokers and provide specific requirements that limit the type of investments that may be made with such funds. Accordingly, we invest these funds in cash and U.S. Treasury fund accounts. We can earn interest income on these unremitted funds, which is included in investment income in the accompanying consolidated statement of earnings. These unremitted amounts are reported as restricted cash in the accompanying consolidated balance sheet, with the related liability reported as premiums payable to underwriting enterprises. Additionally, several of our foreign subsidiaries are required by various foreign agencies to meet certain liquidity and solvency requirements. We were in compliance with these requirements at December 31, 2022. Related to our third party administration business and in certain of our brokerage operations, we are responsible for client claim funds that we hold in a fiduciary capacity. We do not earn any interest income on the funds held. These client funds have been included in restricted cash, along with a corresponding liability in premiums payable to underwriting enterprises in the accompanying consolidated balance sheet. Premiums and Fees Receivable Premiums and fees receivable in the accompanying consolidated balance sheet are net of allowances for estimated policy cancellations and doubtful accounts. The allowance for estimated policy cancellations was $ 9.3 million and $ 10.0 million at December 31, 2022 and 2021, respectively, which represents a reserve for future reversals in commission and fee revenues related to the potential cancellation of client insurance policies that were in force as of each year end. The allowance for doubtful accounts was $ 11.1 million and $ 8.3 million at December 31, 2022 and 2021, respectively. We establish the allowance for estimated policy cancellations through a charge to revenues and the allowance for doubtful accounts through a charge to operating expenses. Both of these allowances are based on estimates and assumptions using historical data to project future experience. Such estimates and assumptions could change in the future as more information becomes known which could impact the amounts reported and disclosed herein. We periodically review the adequacy of these allowances and make adjustments as necessary. Derivative Instruments We are exposed to market risks, including changes in foreign currency exchange rates and interest rates. To manage the risk related to these exposures, we enter into various derivative instruments that reduce these risks by creating offsetting exposures. In the normal course of business, we are exposed to the impact of foreign currency fluctuations that impact our results of operations and cash flows. We utilize a foreign currency risk management program involving foreign currency derivatives that consist of several monthly put/call options designed to hedge a portion of our future foreign currency disbursements through various future payment dates. To mitigate the counterparty credit risk we only enter into contracts with major financial institutions based upon their credit ratings and other factors. These derivative instrument contracts are cash flow hedges that qualify for hedge accounting and primarily hedge against fluctuations between changes in the British pound and Indian Rupee versus the U.S. dollar. Changes in fair value of the derivative instruments are reflected in other comprehensive earnings in the accompanying consolidated balance sheet. The impact of the hedge at maturity is recognized in the income statement as a component of investment income, compensation and operating expenses depending on the nature of the hedged item. We enter into various long-term debt agreements. We use interest rate derivatives, typically swaps, to reduce our exposure to the effects of interest rate fluctuations on the forecasted interest rates for up to three years into the future. These derivative instrument contracts are periodically monitored for hedge ineffectiveness, the amount of which has not been material to the accompanying consolidated financial statements. We do not use derivatives for trading or speculative purposes. Premium Financing Seven subsidiaries of the brokerage segment make short-term loans (generally with terms of twelve months or less) to our clients to finance premiums. These premium financing contracts are structured to minimize potential bad debt expense to us. Such receivables are generally considered delinquent after seven days of the payment due date. In normal course, insurance policies are canceled within one month of the contractual payment due date if the payment remains delinquent. We recognize interest income as it is earned over the life of the contract using the “level-yield” method. Unearned interest related to contracts receivable is included in the receivable balance in the accompanying consolidated balance sheet. The outstanding loan receivable balance was $ 546.3 million and $ 509.7 million at December 31, 2022 and 2021, respectively. Fixed Assets We carry fixed assets at cost, less accumulated depreciation, in the accompanying consolidated balance sheet. We periodically review long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying value of the assets may not be recoverable. Under those circumstances, if the fair value were less than the carrying amount of the asset, we would recognize a loss for the difference. Depreciation for fixed assets is computed using the straight-line method over the following estimated useful lives: Useful Life Office equipment Three to ten years Furniture and fixtures Three to ten years Computer equipment Three to five years Building Fifteen to forty years Software Three to five years Refined fuel plants Ten years Leasehold improvements Shorter of the lease term or useful life of the asset Intangible Assets Intangible assets represent the excess of cost over the estimated fair value of net tangible assets of acquired businesses. Our primary intangible assets are classified as either goodwill, expiration lists, non-compete agreements or trade names. Expiration lists, non‑compete agreements and trade names are amortized using the straight-line method over their estimated useful lives ( two to fifteen years for expiration lists, two to six years for non-compete agreements and two to fifteen years for trade names), while goodwill is not subject to amortization. The establishment of goodwill, expiration lists, non-compete agreements and trade names and the determination of estimated useful lives are primarily based on valuations we receive from qualified independent appraisers. The calculations of these amounts are based on estimates and assumptions using historical and projected financial information and recognized valuation methods. Different estimates or assumptions could produce different results. We carry identifiable intangible assets at cost, less accumulated amortization, in the accompanying consolidated balance sheet. We review all of our intangible assets for impairment periodically (at least annually for goodwill) and whenever events or changes in business circumstances indicate that the carrying value of the assets may not be recoverable. We perform such impairment reviews at the division (i.e., reporting unit) level with respect to goodwill and at the business unit level for amortizable intangible assets. While goodwill is not amortizable, it is tested for impairment at least annually in the fourth quarter, and more frequently if there are indicators of impairment or whenever business circumstances suggest that the carrying value of goodwill may not be recoverable. We may initially perform a qualitative analysis to determine if it is more likely than not that the goodwill balance is impaired. If a qualitative assessment is not performed or if a determination is made that it is not more likely than not that the fair value of the reporting unit exceeds its carrying amount, then we will perform a quantitative analysis. The fair value of each reporting unit is compared to its carrying value. If the fair value of the reporting unit is less than its carrying value, a non-cash impairment charge is recognized for the amount by which the carrying value exceeds the reporting unit’s fair value with the loss not exceeding the total amount of goodwill allocated to that reporting unit. We completed our 2022 annual assessment in the fourth quarter and concluded goodwill was not impaired, as the fair value of each reporting unit exceeded its carrying value. The carrying value of amortizable intangible assets attributable to each business or asset group is periodically reviewed by management to determine if there are events or changes in circumstances that would indicate that its carrying amount may not be recoverable. Accordingly, if there are any such changes in circumstances during the year, we assess the carrying value of the amortizable intangible assets by considering the estimated future undiscounted cash flows generated by the corresponding business or asset group. Any impairment identified through this assessment may require that the carrying value of related amortizable intangible assets be adjusted and charged against current period earnings as a component of amortization expense. Based on the results of impairment reviews in 2022, 2021 and 2020, we wrote off $ 2.0 million, $ 17.6 million and $ 51.7 million, respectively, of amortizable intangible assets primarily related to acquisitions (made prior to 2020) of our brokerage and risk management segments, which is included in amortization expense in the accompanying consolidated statement of earnings. The determinations of impairment indicators and fair value are based on estimates and assumptions related to the amount and timing of future cash flows and future interest rates. Such estimates and assumptions could change in the future as more information becomes known which could impact the amounts reported and disclosed herein. Income Taxes Our tax rate reflects the statutory tax rates applicable to our taxable earnings and tax planning in the various jurisdictions in which we operate. Significant judgment is required in determining the annual effective tax rate and in evaluating uncertain tax positions. We report a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in our tax return. We evaluate our tax positions using a two-step process. The first step involves recognition. We determine whether it is more likely than not that a tax position will be sustained upon tax examination based solely on the technical merits of the position. The technical merits of a tax position are derived from both statutory and judicial authority (legislation and statutes, legislative intent, regulations, rulings and case law) and their applicability to the facts and circumstances of the position. If a tax position does not meet the “more likely than not” recognition threshold, we do not recognize the benefit of that position in the financial statements. The second step is measurement. A tax position that meets the “more likely than not” recognition threshold is measured to determine the amount of benefit to recognize in the financial statements. The tax position is measured as the largest amount of benefit that has a likelihood of greater than 50% of being realized upon ultimate resolution with a taxing authority. Uncertain tax positions are measured based upon the facts and circumstances that exist at each reporting period and involve significant management judgment. Subsequent changes in judgment based upon new information may lead to changes in recognition, derecognition and measurement. Adjustments may result, for example, upon resolution of an issue with the taxing authorities, or expiration of a statute of limitations barring an assessment for an issue. We recognize interest and penalties, if any, related to unrecognized tax benefits in our provision for income taxes. Tax law requires certain items to be included in our tax returns at different times than such items are reflected in the financial statements. As a result, the annual tax expense reflected in our consolidated statements of earnings is different than that reported in our

Effect of New Accounting Pronou

Effect of New Accounting Pronouncements	12 Months Ended
Effect of New Accounting Pronouncements	Dec. 31, 2022
Accounting Changes and Error Corrections [Abstract]
Effect of New Accounting Pronouncements	2. Effect of New Accounting Pronouncements All new accounting pronouncements are either not applicable or deemed not material to our consolidated financial statements.

Business Combinations

Business Combinations	12 Months Ended
Business Combinations	Dec. 31, 2022
Business Combinations [Abstract]
Business Combinations	3. Business Combinations During 2022, we acquired substantially all of the net assets of the following firms in exchange for our common stock and/or cash. These acquisitions have been accounted for using the acquisition method for recording business combinations (in millions, except share data): Name and Effective Date of Acquisition Common Common Cash Accrued Escrow Recorded Total Maximum (000s) Devitt Insurance Services Ltd — $ — $ 73.6 $ 1.3 $ 3.4 $ 12.6 $ 90.9 $ 12.5 Innovu Group Holding — — 85.4 — — — 85.4 — f3 Companies 352 61.7 33.1 — 5.0 6.1 105.9 25.0 M&T Insurance Agency — — 171.0 — — — 171.0 — PlUS Limited LLC 74 10.6 35.6 — 3.8 116.4 166.4 150.0 Thirty-two other acquisitions 300 50.6 457.2 41.7 27.0 106.9 683.4 230.2 726 $ 122.9 $ 855.9 $ 43.0 $ 39.2 $ 242.0 $ 1,303.0 $ 417.7 On December 20, 2022, we signed a definitive agreement to acquire the partnership interests of BCHR holdings, L.P. and its subsidiaries dba Buck (which we refer to as Buck), for a gross consideration of $ 660.0 million or approximately $ 585.0 million net of agreed seller funded expenses and net working capital. We expect to fund the transaction via free cash flow and short-term borrowings. Buck is a leading provider of retirement, human resource and employee benefits consulting and administration services. Buck has been in existence for more than 100 years and has a diverse client base by both size and industry. Buck has over 2,300 employees, including more than 220 credentialed actuaries, and primarily serves customers throughout the U.S., Canada and the United Kingdom (U.K). The transaction is expected to close during the first half of 2023, subject to customary regulatory approvals. On December 1, 2021, we acquired substantially all of the Willis Towers Watson plc treaty reinsurance brokerage operations (which we refer to as Willis Re) for an initial gross consideration of $ 3.17 billion, and potential additional consideration of $ 750 million subject to certain third-year revenue targets. There were twelve remaining international operations with deferred closings that comprised approximately $ 180 million of the initial purchase consideration that were subject to local regulatory approval and closed in 2022. As of the initial closing date, we were the beneficial owners of the operating activity for the twelve deferred closing locations. Together with our existing reinsurance operations, the combined businesses now trades as Gallagher Re. Common shares issued in connection with acquisitions are valued at closing market prices as of the effective date of the applicable acquisition or on the days when the shares are issued, if purchase consideration is deferred. We record escrow deposits that are returned to us as a result of adjustments to net assets acquired as reductions of goodwill when the escrows are settled. The maximum potential earnout payables disclosed in the foregoing table represent the maximum amount of additional consideration that could be paid pursuant to the terms of the purchase agreement for the applicable acquisition. The amounts recorded as earnout payables, which are primarily based upon the estimated future operating results of the acquired entities over a two- to three-year period subsequent to the acquisition date, are measured at fair value as of the acquisition date and are included on that basis in the recorded purchase price consideration in the foregoing table. We will record subsequent changes in these estimated earnout obligations, including the accretion of discount, in our consolidated statement of earnings when incurred. The fair value of these earnout obligations is based on the present value of the expected future payments to be made to the sellers of the acquired entities in accordance with the provisions outlined in the respective purchase agreements, which is a Level 3 fair value measurement. In determining fair value, we estimated the acquired entity’s future performance using financial projections developed by management for the acquired entity and market participant assumptions that were derived for revenue growth and/or profitability. Revenue growth rates generally ranged from 3.0 % to 18.5 % for our 2022 acquisitions. We estimated future payments using the earnout formula and performance targets specified in each purchase agreement and the financial projections just described. We then discounted these payments to present value using a risk-adjusted rate that takes into consideration market‑based rates of return that reflect the ability of the acquired entity to achieve the targets. The discount rates generally ranged from 7.5 % to 10.8 % for our 2022 acquisitions. Changes in financial projections, market participant assumptions for revenue growth and/or profitability, or the risk-adjusted discount rate, would result in a change in the fair value of recorded earnout obligations. During 2022, 2021 and 2020, we recognized $ 61.0 million, $ 35.7 million and $ 32.5 million, respectively, of expense in our consolidated statement of earnings related to the accretion of the discount recorded for earnout obligations in connection with our acquisitions. In addition, during 2022, 2021 and 2020, we recognized $ 22.0 million of expense, $ 83.9 million of expense and $ 65.4 million of income, respectively, related to net adjustments in the estimated fair value of the liability for earnout obligations in connection with revised assumptions due to changes in interest rates volatility and other assumptions and projections of future performance for 89 , 99 and 135 acquisitions, respectively. The net adjustments during 2022, include changes made to the estimated fair value of the Willis Re acquisition earnout and reflect updated assumptions as of December 31, 2022. The aggregate amount of maximum earnout obligations related to acquisitions made in 2019 and subsequent years was $ 1,946.2 million as of December 31, 2022, of which $ 1,077.3 million was recorded in the consolidated balance sheet as of that date based on the estimated fair value of the expected future payments to be made, of which approximately $ 734.0 million can be settled in cash or stock at our option and $ 343.3 million must be settled in cash. The aggregate amount of maximum earnout obligations related to acquisitions made in 2017 and subsequent years was $ 1,873.9 million as of December 31, 2021, of which $ 988.5 million was recorded in the consolidated balance sheet as of that date based on the estimated fair value of the expected future payments to be made, of which approximately $ 670.3 million can be settled in cash or stock at our option and $ 318.2 million must be settled in cash. The following is a summary of the estimated fair values of the net assets acquired at the date of each acquisition made in 2022 (in millions): DIS IGH f3 M&T PIU Thirty-two Other Total Cash and restricted cash $ 3.9 $ 7.8 $ — $ 6.1 $ 2.8 $ 30.9 $ 51.5 Other current assets 18.5 6.5 0.1 27.6 — 73.9 126.6 Fixed assets 0.4 0.5 — 0.2 — 2.1 3.2 Noncurrent assets 1.3 2.0 1.8 1.4 — 11.0 17.5 Goodwill 60.4 47.2 40.5 87.0 116.4 358.4 709.9 Expiration lists 29.0 35.0 65.1 78.9 44.6 311.4 564.0 Non-compete agreements 0.7 4.0 0.2 0.9 1.0 12.7 19.5 Trade names 0.9 0.8 — — 4.0 0.4 6.1 Total assets acquired 115.1 103.8 107.7 202.1 168.8 800.8 1,498.3 Current liabilities 15.3 11.2 0.3 30.2 2.4 90.9 150.3 Noncurrent liabilities 8.9 7.2 1.5 0.9 — 26.5 45.0 Total liabilities assumed 24.2 18.4 1.8 31.1 2.4 117.4 195.3 Total net assets acquired $ 90.9 $ 85.4 $ 105.9 $ 171.0 $ 166.4 $ 683.4 $ 1,303.0 Among other things, these acquisitions allow us to expand into desirable geographic locations, further extend our presence in the retail and wholesale insurance and reinsurance brokerage markets and increase the volume of general services currently provided. The excess of the purchase price over the estimated fair value of the tangible net assets acquired at the acquisition date was allocated to goodwill, expiration lists, non-compete agreements and trade names in the amounts of $ 709.9 million, $ 564.0 million, $ 19.5 million and $ 6.1 million, respectively, within the brokerage and risk management segments. The fair value of the tangible assets and liabilities for each applicable acquisition at the acquisition date approximated their carrying values. In general, the fair value of expiration lists was established using the excess earnings method, which is an income approach based on estimated financial projections developed by management for each acquired entity using market participant assumptions. Revenue growth and attrition rates generally ranged from 3.0 % to 5.2 % and 5.5 % to 9.5 % for our 2022 and 2021 acquisitions, respectively, for which valuations were performed in 2022. We estimate the fair value as the present value of the benefits anticipated from ownership of the subject expiration list in excess of returns required on the investment in contributory assets necessary to realize those benefits. The rate used to discount the net benefits was based on a risk-adjusted rate that takes into consideration market-based rates of return and reflects the risk of the asset relative to the acquired business. These discount rates generally ranged from 10.0 % to 16.5 % for our 2022 and 2021 acquisitions, for which valuations were performed in 2022. The fair value of non-compete agreements was established using the profit differential method, which is an income approach based on estimated financial projections developed by management for the acquired company using market participant assumptions and various non-compete scenarios. Provisional estimates of fair value are established at the time of each acquisition and are subsequently reviewed and finalized within the first year of operations subsequent to the acquisition date to determine the necessity for adjustments. During this period, we may use independent third-party valuation specialists to assist us in finalizing the fair value of assets acquired and liabilities assumed. Fair value adjustments, if any, are most common to the values established for amortizable intangible assets, including expiration lists, non‑compete agreements, acquired software, and for earnout liabilities, with the offset to goodwill, net of any income tax effect. Provisional estimates of fair value were used by us to initially record the acquisition of Willis Re as of the December 1, 2021 acquisition date. We used independent third-party valuation specialists to assist us in determining the fair value of assets acquired and liabilities assumed for this transaction. As of December 31, 2022, the specialists completed their analysis and the fair value estimates have been finalized. Based on the work performed in 2022, we made adjustments to the amounts initially recorded for expiration lists, acquired software and for earnout liability. As a result of these adjustments, the amount allocated to expiration lists decreased by $ 608.0 million, the amount allocated to acquired software increased by $ 59.1 million and the fair value of the earnout liability as of the acquisition date decreased by $ 1.6 million. In addition, a net working capital adjustment of $ 106.0 million was recorded in 2022, related to this transaction, which resulted in a decrease in the initial purchase price consideration paid. These non-cash adjustments resulted in a net increase in goodwill of $ 441.3 million. The reason for the lower value allocated to expiration lists is due to receipt of additional information regarding average customer lives and the higher value allocated to the acquired software which is a result of the incorporation of additional information related to the licensing of certain software applications. Expiration lists, non-compete agreements and trade names related to our acquisitions are amortized using the straight-line method over their estimated useful lives ( two to fifteen years for expiration lists, two to six years for non-compete agreements and two to fifteen years for trade names), while goodwill is not subject to amortization. We use the straight-line method to amortize these intangible assets because the pattern of their economic benefits cannot be reasonably determined with any certainty. We review all of our identifiable intangible assets for impairment periodically (at least annually) and whenever events or changes in business circumstances indicate that the carrying value of the assets may not be recoverable. In reviewing identifiable intangible assets, if the undiscounted future cash flows were less than the carrying amount of the respective (or underlying) asset, an indicator of impairment would exist and further analysis would be required to determine whether or not a loss would need to be charged against current period earnings as a component of amortization expense. Based on the results of impairment reviews in 2022, 2021 and 2020, we wrote off $ 2.0 million, $ 17.6 million and $ 51.7 million, respectively, of amortizable intangible assets related to the brokerage and risk management segments. Of the $ 564.0 million of expiration lists, $ 19.5 million of non-compete agreements and $ 6.1 million of trade names related to the 2022 acquisitions, $ 127.8 million, $ 8.5 million and $ 2.0 million, respectively, is not expected to be deductible for income tax purposes. Accordingly, we recorded a deferred tax liability of $ 29.6 million, and a corresponding amount of goodwill, in 2022 related to the nondeductible amortizable intangible assets. Our consolidated financial statements for the year ended December 31, 2022 include the operations of the acquired entities from their respective acquisition dates. The following is a summary of the unaudited pro forma historical results, as if these entities had been acquired at January 1, 2021 (in millions, except per share data): Year Ended December 31, 2022 2021 Total revenues $ 8,710.2 $ 8,445.8 Net earnings attributable to controlling interests 1,114.8 907.1 Basic net earnings per share 5.29 4.46 Diluted net earnings per share 5.18 4.36 The unaudited pro forma results above have been prepared for comparative purposes only and do not purport to be indicative of the results of operations which actually would have resulted had these acquisitions occurred at January 1, 2021, nor are they necessarily indicative of future operating results. Annualized revenues of entities acquired in 2022 totaled approximately $ 246.5 million. Total revenues and net loss recorded in our consolidated statement of earnings for 2022 related to the 2022 acquisitions in the aggregate, were $ 87.9 million and $( 0.7 ) million, respectively.

Contracts with Customers

Contracts with Customers	12 Months Ended
Contracts with Customers	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Contracts with Customers	4. Contracts with Customers Contract Assets and Liabilities/Contract Balances Information about unbilled receivables, contract assets and contract liabilities from contracts with customers is as follows (in millions): December 31, 2022 December 31, 2021 Unbilled receivables $ 910.9 $ 730.0 Deferred contract costs 144.5 129.7 Deferred revenue 609.3 579.6 The unbilled receivables, which are included in premium and fees receivable in our consolidated balance sheet, primarily relate to our rights to consideration for work completed but not billed at the reporting date. These are transferred to the receivables when the client is billed. The deferred contract costs represent the costs we incur to fulfill a new or renewal contract with our clients prior to the effective date of the contract. These costs are expensed on the contract effective date. The deferred revenue in the consolidated balance sheet included amounts that represent the remaining performance obligations under our contracts and amounts collected related to advanced billings and deposits received from customers that may or may not ultimately be recognized as revenues in the future. Deposits received from customers could be returned to the customers based on lesser actual transactional volume than originally billed volume. Significant changes in the deferred revenue balances, which include foreign currency translation adjustments, during the period are as follows (in millions): Brokerage Risk Total Deferred revenue at December 31, 2020 $ 354.7 $ 186.6 $ 541.3 Incremental deferred revenue 325.0 102.1 427.1 Revenue recognized during the year ended December 31, ( 296.1 ) ( 103.5 ) ( 399.6 ) Net change in collected billings/deposits received from customers ( 3.6 ) ( 0.7 ) ( 4.3 ) Impact of changes in foreign exchange rates ( 3.7 ) ( 0.8 ) ( 4.5 ) Deferred revenue recognized from business acquisitions 19.6 — 19.6 Deferred revenue at December 31, 2021 395.9 183.7 579.6 Incremental deferred revenue 342.3 103.2 445.5 Revenue recognized during the year ended December 31, ( 326.3 ) ( 104.6 ) ( 430.9 ) Net change in collected billings/deposits received from customers 21.4 ( 7.0 ) 14.4 Impact of changes in foreign exchange rates ( 17.9 ) — ( 17.9 ) Deferred revenue recognized from business acquisitions 18.6 — 18.6 Deferred revenue at December 31, 2022 $ 434.0 $ 175.3 $ 609.3 Revenue recognized during 2022 in the table above included revenue from 2021 acquisitions that would not be reflected in prior years. Remaining Performance Obligations Remaining performance obligations represent the portion of the contract price for which work has not been performed. As of December 31, 2022 , the aggregate amount of the contract price allocated to remaining performance obligations was $ 609.3 million. The estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied) at the end of the reporting period is as follows (in millions): Brokerage Risk Total 2023 $ 404.6 $ 48.4 $ 453.0 2024 26.3 64.5 90.8 2025 1.4 27.2 28.6 2026 0.8 14.4 15.2 2027 0.5 8.4 8.9 Thereafter 0.4 12.4 12.8 Total $ 434.0 $ 175.3 $ 609.3 Deferred Contract Costs We capitalize costs incurred to fulfill contracts as “deferred contract costs” which are included in other current assets in our consolidated balance sheet. Deferred contract costs were $ 144.5 million and $ 129.7 million as of December 31, 2022 and 2021, respectively. Capitalized fulfillment costs are amortized to expense on the contract effective date. The amount of amortization of the deferred contract costs was $ 504.4 million and $ 425.5 million for the years ended December 31, 2022 and 2021, respectively. We have applied the practical expedient to recognize the incremental costs of obtaining contracts as an expense when incurred if the amortization period of the assets that we otherwise would have recognized is one year or less for our brokerage segment. These costs are included in compensation and operating expenses in our consolidated statement of earnings.

Other Financial Data

Other Financial Data	12 Months Ended
Other Financial Data	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Financial Data	5. Other Financial Data Other Current Assets Major classes of other current assets consist of the following (in millions): December 31, 2022 2021 Premium finance advances and loans $ 546.3 $ 509.7 Accrued supplemental, direct bill and other receivables 567.8 563.0 Refined coal production related receivables 5.7 76.9 Deferred contract costs 144.5 129.7 Prepaid expenses 197.2 171.7 Total other current assets $ 1,461.5 $ 1,451.0 The premium finance advances and loans represent short-term loans which we make to many of our brokerage related clients and other non‑brokerage clients to finance their premiums paid to underwriting enterprises. These premium finance advances and loans are primarily generated by three Australian and New Zealand premium finance subsidiaries. Financing receivables are carried at amortized cost. Given that these receivables carry a fairly rapid delinquency period of only seven days post payment date, and that contractually the majority of the underlying insurance policies will be canceled within one month of the payment due date in normal course, there historically has been a minimal risk of not receiving payment, and therefore we do not maintain any significant allowance for losses against this balance.

Fixed Assets

Fixed Assets	12 Months Ended
Fixed Assets	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Fixed Assets	6. Fixed Assets Major classes of fixed assets consist of the following (in millions): December 31, 2022 2021 Office equipment $ 32.2 $ 36.2 Furniture and fixtures 142.0 137.1 Leasehold improvements 190.7 170.8 Computer equipment 295.8 247.1 Land and buildings - corporate headquarters 145.3 145.3 Software 583.4 532.2 Other 16.9 17.2 Work in process 56.0 23.0 1,462.3 1,308.9 Accumulated depreciation ( 886.1 ) ( 808.1 ) Net fixed assets $ 576.2 $ 500.8 The amounts in work in process in the table above primarily are for capitalized expenditures incurred related to IT development projects in 2022 and 2021.

Intangible Assets

Intangible Assets	12 Months Ended
Intangible Assets	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	7. Intangible Assets The carrying amount of goodwill at December 31, 2022 and 2021 allocated by domestic and foreign operations is as follows (in millions): Brokerage Risk Corporate Total At December 31, 2022 United States $ 5,065.7 $ 74.8 $ — $ 5,140.5 United Kingdom 2,180.2 17.7 — 2,197.9 Canada 569.7 — — 569.7 Australia 467.6 10.2 — 477.8 New Zealand 203.8 9.5 — 213.3 Other foreign 871.1 — 19.1 890.2 Total goodwill - net $ 9,358.1 $ 112.2 $ 19.1 $ 9,489.4 At December 31, 2021 United States $ 4,409.1 $ 64.8 $ — $ 4,473.9 United Kingdom 2,198.7 15.0 — 2,213.7 Canada 572.9 — — 572.9 Australia 487.2 10.9 — 498.1 New Zealand 217.6 10.2 — 227.8 Other foreign 659.1 — 20.7 679.8 Total goodwill - net $ 8,544.6 $ 100.9 $ 20.7 $ 8,666.2 The changes in the carrying amount of goodwill for 2022 and 2021 are as follows (in millions): Brokerage Risk Corporate Total Balance as of December 31, 2020 $ 6,053.6 $ 70.5 $ 2.9 $ 6,127.0 Goodwill acquired during the year 2,511.8 31.6 18.1 2,561.5 Goodwill adjustments related to appraisals and other acquisition 50.8 — — 50.8 Goodwill written-off related to sales of business ( 1.0 ) — — ( 1.0 ) Foreign currency translation adjustments during the year ( 70.6 ) ( 1.2 ) ( 0.3 ) ( 72.1 ) Balance as of December 31, 2021 8,544.6 100.9 20.7 8,666.2 Goodwill acquired during the year 693.9 16.0 — 709.9 Goodwill adjustments related to appraisals and other acquisition 428.3 ( 1.6 ) 0.2 426.9 Foreign currency translation adjustments during the year ( 308.7 ) ( 3.1 ) ( 1.8 ) ( 313.6 ) Balance as of December 31, 2022 $ 9,358.1 $ 112.2 $ 19.1 $ 9,489.4 Major classes of amortizable intangible assets consist of the following (in millions): December 31, 2022 2021 Expiration lists $ 6,472.3 $ 6,696.8 Accumulated amortization - expiration lists ( 3,178.5 ) ( 2,812.2 ) 3,293.8 3,884.6 Non-compete agreements 91.3 76.0 Accumulated amortization - non-compete agreements ( 67.5 ) ( 62.8 ) 23.8 13.2 Trade names 108.5 105.2 Accumulated amortization - trade names ( 54.0 ) ( 49.0 ) 54.5 56.2 Net amortizable assets $ 3,372.1 $ 3,954.0 Estimated aggregate amortization expense for each of the next five years is as follows (in millions): 2023 $ 466.1 2024 429.5 2025 388.5 2026 349.7 2027 320.3 Thereafter 1,418.0 Total $ 3,372.1

Credit and Other Debt Agreement

Credit and Other Debt Agreements	12 Months Ended
Credit and Other Debt Agreements	Dec. 31, 2022
Debt Disclosure [Abstract]
Credit and Other Debt Agreements	8. Credit and Other Debt Agreements The following is a summary of our corporate and other debt (in millions): December 31, 2022 2021 Senior Notes: Semi-annual payments of interest, fixed rate of 2.40 %, balloon due November 9, 2031 $ 400.0 $ 400.0 Semi-annual payments of interest, fixed rate of 3.50 %, balloon due May 20, 2051 850.0 850.0 Semi-annual payments of interest, fixed rate of 3.05 %, balloon due March 9, 2052 350.0 350.0 Total Senior Notes 1,600.0 1,600.0 Note Purchase Agreements: Semi-annual payments of interest, fixed rate of 3.69 %, balloon due June 14, 2022 — 200.0 Semi-annual payments of interest, fixed rate of 5.49 %, balloon due February 10, 2023 50.0 50.0 Semi-annual payments of interest, fixed rate of 4.13 %, balloon due June 24, 2023 200.0 200.0 Semi-annual payments of interest, fixed rate of 4.72 %, balloon due February 13, 2024 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.58 %, balloon due February 27, 2024 325.0 325.0 Quarterly payments of interest, floating rate of 90 day LIBOR plus 1.40 %, balloon due June 13, 2024 50.0 50.0 Semi-annual payments of interest, fixed rate of 4.31 %, balloon due June 24, 2025 200.0 200.0 Semi-annual payments of interest, fixed rate of 4.85 %, balloon due February 13, 2026 140.0 140.0 Semi-annual payments of interest, fixed rate of 4.73 %, balloon due February 27, 2026 175.0 175.0 Semi-annual payments of interest, fixed rate of 4.40 %, balloon due June 2, 2026 175.0 175.0 Semi-annual payments of interest, fixed rate of 4.36 %, balloon due June 24, 2026 150.0 150.0 Semi-annual payments of interest, fixed rate of 3.75 %, balloon due January 30, 2027 30.0 30.0 Semi-annual payments of interest, fixed rate of 4.09 %, balloon due June 27, 2027 125.0 125.0 Semi-annual payments of interest, fixed rate of 4.09 %, balloon due August 2, 2027 125.0 125.0 Semi-annual payments of interest, fixed rate of 4.14 %, balloon due August 4, 2027 98.0 98.0 Semi-annual payments of interest, fixed rate of 3.46 %, balloon due December 1, 2027 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.55 %, balloon due June 2, 2028 75.0 75.0 Semi-annual payments of interest, fixed rate of 4.34 %, balloon due June 13, 2028 125.0 125.0 Semi-annual payments of interest, fixed rate of 5.04 %, balloon due February 13, 2029 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.98 %, balloon due February 27, 2029 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.19 %, balloon due June 27, 2029 50.0 50.0 Semi-annual payments of interest, fixed rate of 4.19 %, balloon due August 2, 2029 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.48 %, balloon due December 2, 2029 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.99 %, balloon due January 30, 2030 341.0 341.0 Semi-annual payments of interest, fixed rate of 4.44 %, balloon due June 13, 2030 125.0 125.0 Semi-annual payments of interest, fixed rate of 5.14 %, balloon due March 13, 2031 180.0 180.0 Semi-annual payments of interest, fixed rate of 4.70 %, balloon due June 2, 2031 25.0 25.0 Semi-annual payments of interest, fixed rate of 4.09 %, balloon due January 30, 2032 69.0 69.0 Semi-annual payments of interest, fixed rate of 4.34 %, balloon due June 27, 2032 75.0 75.0 Semi-annual payments of interest, fixed rate of 4.34 %, balloon due August 2, 2032 75.0 75.0 Semi-annual payments of interest, fixed rate of 4.59 %, balloon due June 13, 2033 125.0 125.0 Semi-annual payments of interest, fixed rate of 5.29 %, balloon due March 13, 2034 40.0 40.0 Semi-annual payments of interest, fixed rate of 4.48 %, balloon due June 12, 2034 175.0 175.0 Semi-annual payments of interest, fixed rate of 4.24 %, balloon due January 30, 2035 79.0 79.0 Semi-annual payments of interest, fixed rate of 2.44 %, balloon due February 10, 2036 100.0 100.0 Semi-annual payments of interest, fixed rate of 2.46 %, balloon due May 5, 2036 75.0 75.0 Semi-annual payments of interest, fixed rate of 4.69 %, balloon due June 13, 2038 75.0 75.0 Semi-annual payments of interest, fixed rate of 5.45 %, balloon due March 13, 2039 40.0 40.0 Semi-annual payments of interest, fixed rate of 4.49 %, balloon due January 30, 2040 56.0 56.0 Total Note Purchase Agreements 4,248.0 4,448.0 Credit Agreement: Periodic payments of interest and principal, prime or SOFR plus up to 1.40 %, expires June 7, 2024 60.0 45.0 Premium Financing Debt Facility - expires September 15, 2024 : Facility B AUD denominated tranche, interbank rates plus 1.500 % 217.6 209.5 NZD denominated tranche, interbank rates plus 1.850 % — 6.8 Facility C and D AUD denominated tranche, interbank rates plus 0.830 % 15.2 2.1 NZD denominated tranche, interbank rates plus 0.990 % 9.1 10.0 Total Premium Financing Debt Facility 241.9 228.4 Total corporate and other debt 6,149.9 6,321.4 Less unamortized debt acquisition costs on Senior Notes and Note Purchase Agreements ( 20.6 ) ( 22.6 ) Less unamortized discount on Bonds Payable ( 14.6 ) ( 15.2 ) Net corporate and other debt $ 6,114.7 $ 6,283.6 The Senior Notes in the table above are registered by the company with the Securities and Exchange Commission and are not guaranteed. Senior Notes - On May 20, 2021, we closed and funded an offering of $ 1,500.0 million of unsecured senior notes in two tranches. The $ 650.0 million aggregate principal amount of 2.50 % Senior Notes were due 2031 (which we refer to as the 2031 May Notes) and the $ 850.0 million aggregate principal amount of 3.50 % Senior Notes are due 2051 (which we refer to as the 2051 May Notes and together with the 2031 May Notes, the May Notes). The weighted average interest rate is 3.31 % per annum after giving effect to underwriting costs and the net hedge loss. In 2018 and 2019, we entered into a pre-issuance interest rate hedging transaction related to these notes. We realized a net cash loss of approximately $ 57.8 million on the hedging transactions that will be recognized on a pro rata basis as an increase to our reported interest expense over a ten year period. The offering of the May Notes was made pursuant to a shelf registration statement filed with the SEC. The relevant terms of the May Notes, the Indenture and the Officer’s Certificate are further described under the caption “Description of Notes” in the prospectus supplement dated May 13, 2021, filed with the SEC on May 17, 2021. The 2031 May Notes had a special optional redemption whereby, we had the option to redeem the 2031 May Notes in whole and not in part, by providing notice of such redemption to the holders of the 2031 May Notes within 30 days following a Willis Re transaction termination event, at redemption price equal to 101 % of the aggregate principal amount of the 2031 May Notes, plus any accrued and unpaid interest. These notes were redeemed on August 13, 2021 . As a result of the redemption of this debt, we incurred a loss on extinguishment of debt $ 16.2 million, which included the redemption price premium of $ 6.5 million, which is presented in cash flows from financing activities, and the unamortized discount amount on the debt issuance and the write-off of all the debt acquisition costs of $ 9.7 million, which is presented in cash flows from operating activities. The 2051 May Notes are not subject to the special optional redemption. We used the net proceeds of the 2051 May Notes offering to fund a portion of the cash consideration payable in connection with the Willis Re transaction. On November 9, 2021, we closed and funded an offering of $ 750.0 million of unsecured senior notes in two tranches. The $ 400.0 million aggregate principal amount of 2.40 % Senior Notes are due 2031 (which we refer to as the 2031 November Notes) and $ 350.0 million aggregate principal amount of 3.05 % Senior Notes are due 2052 (which we refer to as the 2052 November Notes and together with the 2031 November Notes, the November Notes). The weighted average interest rate is 2.80 % per annum after giving effect to underwriting costs. The November Notes were issued pursuant to an indenture, dated as of May 20, 2021, as modified and supplemented in respect of the November Notes by an Officer’s Certificate pursuant to the indenture, dated as of November 9, 2021. The relevant terms of the November Notes, the indenture and the Officer’s Certificate are further described under the caption “Description of Notes” in the prospectus supplement filed with the SEC on November 3, 2021. We used the net proceeds of the November Notes this offering to fund a portion of the cash consideration payable in connection with the Willis Re transaction. Note Purchase Agreements - On February 10, 2021, we closed a private placement of $ 100.0 million aggregate principal amount of unsecured senior notes. The unsecured senior notes were issued with an interest rate of 2.44 % and are due in 2036 . We used the proceeds of these offerings in part to fund the $ 75.0 million February 10, 2021 Series D note maturity, and for acquisitions and general corporate purposes. The weighted average interest rate is 3.97 % after giving effect to a net hedging loss. In 2018, we entered into a pre-issuance interest rate hedging transaction related to this private placement. We realized a net cash loss of approximately $ 22.9 million on the hedging transactions that will be recognized on a pro rata basis as an increase in our reported interest expense over ten years of the total 15 ‑year notes. On May 5, 2021, we closed and funded a private placement of $ 75.0 million aggregate principal amount of unsecured senior notes. The unsecured senior notes were issued with an interest rate of 2.46 % and are due in 2036 . We used the proceeds of this offering in part to fund acquisitions and general corporate purposes. The weighted average interest rate is 3.98 % after giving effect to a net hedging loss. In 2018, we entered into a pre-issuance interest rate hedging transaction related to this private placement. We realized a net cash loss of approximately $ 17.2 million on the hedging transactions that will be recognized on a pro rata basis as an increase in our reported interest expense over ten years of the total 15 ‑year notes. We used these offerings to repay certain existing indebtedness and for general corporate purposes, including to fund acquisitions. On June 14, 2022, we used operating cash to fund the $ 200.0 million Series G note maturity. Under the terms of the note purchase agreements described above, we may redeem the notes at any time, in whole or in part, at 100 % of the principal amount of such notes being redeemed, together with accrued and unpaid interest and a “make-whole amount”. The “make-whole amount” is derived from a net present value computation of the remaining scheduled payments of principal and interest using a discount rate based on the U.S. Treasury yield plus 0.5 % and is designed to compensate the purchasers of the notes for their investment risk in the event prevailing interest rates at the time of prepayment are less favorable than the interest rates under the notes. We do not currently intend to prepay any of the notes. The note purchase agreements described above contain customary provisions for transactions of this type, including representations and warranties regarding us and our subsidiaries and various financial covenants, including covenants that require us to maintain specified financial ratios. We were in compliance with these covenants as of December 31, 2022. The note purchase agreements also provide customary events of default, generally with corresponding grace periods, including, without limitation, payment defaults with respect to the notes, covenant defaults, cross-defaults to other agreements evidencing our or our subsidiaries’ indebtedness, certain judgments against us or our subsidiaries and events of bankruptcy involving us or our material subsidiaries. The notes issued under the note purchase agreement are senior unsecured obligations of ours and rank equal in right of payment with our Credit Agreement discussed below. Credit Agreement - On August 27, 2020, we entered into an amendment to our amended and restated multicurrency credit agreement dated June 7, 2019, (which we refer to as the Credit Agreement). The amendment to the Credit Agreement provided that the obligations of each subsidiary of Gallagher that was a borrower, guarantor and/or obligor under the Credit Agreement, ceased to apply and that each subsidiary was released from all of its obligations under the Credit Agreement. The amendment also replaced the minimum asset covenant with a priority indebtedness covenant, substantially similar to other priority indebtedness covenants applicable to us under our private placement note purchase agreements. On December 14, 2022, we entered into a second amendment to the Credit Agreement. The second amendment to the Credit Agreement provided that LIBOR should be replaced with a successor rate. The amendment also included additional terms and conditions for SOFR loans and RFR loans. See below for more detail. The Credit Agreement provides that we may elect that each borrowing in U.S. dollars be either base rate loans or SOFR loans, each as defined in the Credit Agreement. However, the Credit Agreement provides that all loans denominated in currencies other than U.S. dollars will be eurocurrency or risk-free rate (RFR) loans. Interest rates on base rate loans and outstanding drawings on letters of credit in U.S. dollars under the Credit Agreement will be based on the base rate, as defined in the Credit Agreement, plus a margin of 0.00 % to 0.40 %, depending on the financial leverage ratio we maintain. Interest rates on eurocurrency, SOFR loans, RFR loans or outstanding drawings on letters of credit in currencies other than U.S. dollars under the Credit Agreement will be based on adjusted SOFR rate, eurocurrency rate or RFR rate, as applicable, as defined in the Credit Agreement, plus a margin of 0.825 % to 1.40 %, depending on the financial leverage ratio we maintain. Interest rates on swing loans will be based, at our election, on either the base rate or an alternate rate that may be quoted by the lead lender. The annual facility fee related to the Credit Agreement is 0.125 % and 0.250 % of the revolving credit commitment, depending on the financial leverage ratio we maintain. The terms of the Credit Agreement include various financial covenants, including covenants that require us to maintain specified financial ratios. We were in compliance with these covenants as of December 31, 2022. The Credit Agreement also includes customary provisions for transactions of this type, including events of default, with corresponding grace periods and cross‑defaults to other agreements evidencing our indebtedness. At December 31, 2022 , $ 10.6 million of letters of credit (for which we had $ 17.4 million of liabilities recorded at December 31, 2022 ) were outstanding under the Credit Agreement. See Note 17 to these consolidated financial statements for a discussion of the letters of credit. There was $ 60.0 million of borrowings outstanding under the Credit Agreement at December 31, 2022. Accordingly, at December 31, 2022 , $ 1,150.6 million remained available for potential borrowings. Premium Financing Debt Facility - On September 20, 2022, we entered into an amendment to our revolving loan facility (which we refer to as the Premium Financing Debt Facility), that provides funding for the three Australian (AU) and New Zealand (NZ) premium finance subsidiaries. The amendment, among other things, extended the expiration date of the Premium Financing Debt Facility from September 15, 2023 to September 15, 2024, and increased the total commitment for the AU$ denominated tranche from AU$ 340.0 million to AU$ 410.0 million. The Premium Financing Debt Facility is comprised of: (i) Facility B is separated into AU$ 350.0 million and NZ$ 25.0 million tranches (the NZ$ tranche will decrease as of May 1, 2023 to NZ$ 10.0 million), (ii) Facility C, an AU$ 60.0 million equivalent multi-currency overdraft tranche and (iii) Facility D, a NZ$ 15.0 million equivalent multi-currency overdraft tranche. The interest rates on Facility B are Interbank rates, which vary by tranche, duration and currency, plus a margin of 1.500 % and 1.850 % for the AU$ and NZ$ tranches, respectively. The interest rates on Facilities C and D are 30 day Interbank rates, plus a margin of 0.830 % and 0.990 % for the AU$ and NZ$ tranches, respectively. The annual fee for Facility B is 0.675 % and 0.8325 % for the undrawn commitments for the AU$ and NZ$ tranches, respectively. The annual fee for Facility C is 0.77 % and for Facility D is 0.90 % of the total commitments of the facilities . The terms of our Premium Financing Debt Facility include various financial covenants, including covenants that require us to maintain specified financial ratios. We were in compliance with these covenants as of December 31, 2022. The Premium Financing Debt Facility also includes customary provisions for transactions of this type, including events of default, with corresponding grace periods and cross-defaults to other agreements evidencing our indebtedness. Facilities B, C and D are secured by the premium finance receivables of the Australian and New Zealand premium finance subsidiaries. At December 31, 2022 , AU$ 325.0 million and NZ$ 0.0 million of borrowings were outstanding under Facility B, AU$ 22.5 million of borrowings outstanding under Facility C and NZ$ 14.5 million of borrowings were outstanding under Facility D, which in aggregate amount to US$ 241.9 million of borrowings under the Premium Finance Debt Facility. Accordingly, as of December 31, 2022 , AU$ 25.0 million and NZ$ 25.0 million remained available for potential borrowing under Facility B, and AU$ 37.5 million and NZ$ 0.5 million under Facilities C and D, respectively. See Note 17 to these consolidated financial statements for additional discussion on our contractual obligations and commitments as of December 31, 2022. The aggregate estimated fair value of the $ 5,848.0 million in debt under our various senior notes and note purchase agreements at December 31, 2022 was $ 4,942.5 million due to the long-term duration and fixed interest rates associated with these debt obligations. No active or observable market exists for our private long-term debt. Therefore, the estimated fair value of this debt is based on the income valuation approach, which is a valuation technique that converts future amounts (for example, cash flows or income and expenses) to a single current (that is, discounted) amount. The fair value measurement is determined on the basis of the value indicated by current market expectations about those future amounts. Because our debt issuances generate a measurable income stream for each lender, the income approach was deemed to be an appropriate methodology for valuing the private placement long-term debt. The methodology used calculated the original deal spread at the time of each debt issuance, which was equal to the difference between the yield of each issuance (the coupon rate) and the equivalent benchmark treasury yield at that time. The market spread as of the valuation date was calculated, which is equal to the difference between an index for investment grade insurers and the equivalent benchmark treasury yield today. An implied premium or discount to the par value of each debt issuance based on the difference between the origination deal spread and market as of the valuation date was then calculated. The index we relied on to represent investment graded insurers was the Bloomberg Valuation Services (BVAL) U.S. Insurers BBB index. This index is comprised primarily of insurance brokerage firms and was representative of the industry in which we operate. For the purpose of our analysis, the average BBB rate was assumed to be the appropriate borrowing rate for us. The estimated fair value of the $ 60.0 million of borrowings outstanding under our Credit Agreement approximate their carrying value due to their short-term duration and variable interest rates. The estimated fair value of the $ 241.9 million of borrowings outstanding under our Premium Financing Debt Facility approximates their carrying value due to their short-term duration and variable interest rates.

Earnings per Share

Earnings per Share	12 Months Ended
Earnings per Share	Dec. 31, 2022
Earnings Per Share [Abstract]
Earnings per Share	9. Earnings per Share The following table sets forth the computation of basic and diluted net earnings per share (in millions, except per share data): Year Ended December 31, 2022 2021 2020 Net earnings attributable to controlling interests $ 1,114.2 $ 906.8 $ 818.8 Weighted average number of common shares outstanding 210.3 202.7 191.0 Dilutive effect of stock options using the treasury stock 4.4 4.6 4.0 Weighted average number of common and common 214.7 207.3 195.0 Basic net earnings per share $ 5.30 $ 4.47 $ 4.29 Diluted net earnings per share $ 5.19 $ 4.37 $ 4.20 Anti-dilutive stock-based awards of 2.0 million, 1.3 million and 1.0 million shares were outstanding at December 31, 2022 , 2021 and 2020, respectively, but were excluded in the computation of the dilutive effect of stock‑based awards for the year then ended. These stock-based awards were excluded from the computation because the exercise prices on these stock-based awards were greater than the average market price of our common shares during the respective period, and therefore, would be anti-dilutive to earnings per share under the treasury stock method.

Stock Option Plans

Stock Option Plans	12 Months Ended
Stock Option Plans	Dec. 31, 2022
Text Block [Abstract]
Stock Option Plans	10. Stock Option Plans On May 10, 2022, our stockholders approved the Arthur J. Gallagher & Co. 2022 Long-Term Incentive Plan (which we refer to as the LTIP), which replaced our previous stockholder-approved Arthur J. Gallagher & Co. 2017 Long-Term Incentive Plan (which we refer to as the 2017 LTIP). The LTIP term began May 10, 2022 and terminates on the date of the annual meeting of stockholders in 2032, unless terminated earlier by our board of directors. All of our officers, employees and non-employee directors are eligible to receive awards under the LTIP. The compensation committee of our board of directors determines the annual number of shares delivered under the LTIP. The LTIP provides for non-qualified and incentive stock options, stock appreciation rights, restricted stock and restricted stock units, any or all of which may be made contingent upon the achievement of performance criteria. Shares of our common stock available for issuance under the LTIP include authorized and unissued shares of common stock or authorized and issued shares of common stock reacquired and held as treasury shares or otherwise, or a combination thereof. The number of available shares will be reduced by the aggregate number of shares that become subject to outstanding awards granted under the LTIP. A maximum of 3.5 million shares issued for full value awards (i.e., awards other than stock options or stock appreciation rights) will be counted one-for-one against the 13.5 million share pool, and every share subject to a full value award in excess of such limit will be counted as 3.8 shares against the pool. To the extent that shares subject to an outstanding award granted under either the LTIP or prior equity plans are not issued or delivered by reason of the expiration, termination, cancellation or forfeiture of such award or by reason of the settlement of such award in cash, then such shares will again be available for grant under the LTIP. The maximum number of shares available under the LTIP for restricted stock, restricted stock unit awards and performance unit awards settled with stock (i.e., all awards other than stock options and stock appreciation rights) is 3.3 million as of December 31, 2022. The LTIP provides for the grant of stock options, which may be either tax-qualified incentive stock options or non-qualified options and stock appreciation rights. The compensation committee determines the period for the exercise of a non-qualified stock option, tax-qualified incentive stock option or stock appreciation right, provided that no option can be exercised later than seven years after its date of grant. The exercise price of a non-qualified stock option or tax-qualified incentive stock option and the base price of a stock appreciation right cannot be less than 100 % of the fair market value of a share of our common stock on the date of grant, provided that the base price of a stock appreciation right granted in tandem with an option will be the exercise price of the related option. Upon exercise, the option exercise price may be paid in cash, by the delivery of previously owned shares of our common stock, through a net-exercise arrangement, or through a broker-assisted cashless exercise arrangement. The compensation committee determines all of the terms relating to the exercise, cancellation or other disposition of an option or stock appreciation right upon a termination of employment, whether by reason of disability, retirement, death or any other reason. Stock option and stock appreciation right awards under the LTIP are non-transferable. On February 1, 2022 and March 15, 2022, the compensation committee granted 1,197,000 and 1,141,000 options, respectively, under the 2017 LTIP to our officers and key employees that become exercisable at the rate of 34 %, 33 % and 33 % on the anniversary date of the grant in 2025, 2026, and 2027, respectively. On March 16, 2021, the compensation committee granted 1,640,000 options under the 2017 LTIP to our officers and key employees that become exercisable at the rate of 34 %, 33 % and 33 % on the anniversary date of the grant in 2024, 2025 and 2026, respectively. On March 12, 2020, the compensation committee granted 1,590,740 options under the 2017 LTIP to our officers and key employees that become exercisable at the rate of 34 %, 33 % and 33 % on the anniversary date of the grant in 2023, 2024 and 2025, respectively. The 2022, 2021 and 2020 options expire seven years from the date of grant, or earlier in the event of certain terminations of employment. For our executive officers age 55 or older, stock options awarded in 2022, 2021 and 2020 are not subject to forfeiture upon such officers’ departure from the company after two years from the date of grant. Our stock option plans provide for the immediate vesting of all outstanding stock option grants in the event of a change in control of our company, as defined in the applicable plan documents. During 2022, 2021 and 2020, we recognized $ 27.9 million, $ 17.5 million and $ 13.6 million, respectively, of compensation expense related to our stock option grants. For purposes of expense recognition in 2022, 2021 and 2020, the estimated fair values of the stock option grants are amortized to expense over the options’ vesting period. We estimated the fair value of stock options at the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: Year Ended December 31, 2022 2021 2020 Expected dividend yield 1.3 % 1.5 % 2.1 % Expected risk-free interest rate 1.9 % 0.9 % 0.7 % Volatility 23.1 % 22.9 % 17.3 % Expected life (in years) 5.4 5.4 5.4 Option valuation models require the input of highly subjective assumptions including the expected stock price volatility. The Black‑Scholes option pricing model was developed for use in estimating the fair value of traded options which have no vesting restrictions and are fully transferable. The weighted average fair value per option for all options granted during 2022, 2021 and 2020, as determined on the grant date using the Black-Scholes option pricing model, was $ 33.25 , $ 23.38 and $ 9.99 , respectively. The following is a summary of our stock option activity and related information for 2022 and 2021 (in millions, except exercise price and year data): Weighted Average Weighted Remaining Shares Average Contractual Aggregate Under Exercise Term Intrinsic Option Price (in years) Value Year Ended December 31, 2022 Beginning balance 7.5 $ 81.30 Granted 2.4 157.74 Exercised ( 1.4 ) 53.53 Forfeited or canceled ( 0.2 ) 109.10 Ending balance 8.3 $ 107.47 4.18 $ 668.9 Exercisable at end of year 1.8 $ 61.11 1.56 $ 230.8 Ending unvested and expected to vest 5.9 $ 118.80 4.86 $ 413.2 Year Ended December 31, 2021 Beginning balance 7.5 $ 65.09 Granted 1.6 127.90 Exercised ( 1.4 ) 49.10 Forfeited or canceled ( 0.2 ) 88.84 Ending balance 7.5 $ 81.30 3.90 $ 666.3 Exercisable at end of year 2.1 $ 51.46 1.57 $ 242.3 Ending unvested and expected to vest 5.1 $ 91.56 4.72 $ 401.7 Options with respect to 13.4 million shares (less any shares of restricted stock issued under the LTIP - see Note 12 to these consolidated financial statements) were available for grant under the LTIP at December 31, 2022. The total intrinsic value of options exercised during 2022, 2021 and 2020 amounted to $ 168.2 million, $ 127.4 million and $ 106.4 million, respectively. As of December 31, 2022 , we had approximately $ 94.3 million of total unrecognized compensation expense related to nonvested options. We expect to recognize that cost over a weighted average period of approximately four years . Other information regarding stock options outstanding and exercisable at December 31, 2022 is summarized as follows (in millions, except exercise price and year data): Options Outstanding Options Exercisable Weighted Average Remaining Weighted Weighted Contractual Average Average Number Term Exercise Number Exercise Range of Exercise Prices Outstanding (in years) Price Exercisable Price $ 43.71 $ — $ 43.71 $ 0.4 $ 0.21 $ 43.71 $ 0.4 $ 43.71 49.55 — 56.86 0.7 1.21 56.84 0.7 56.85 70.74 — 70.74 0.8 2.21 70.74 0.4 70.74 79.59 — 79.59 1.0 3.20 79.59 0.3 79.59 86.17 — 86.17 1.5 4.20 86.17 — 86.17 127.90 — 127.90 1.5 5.21 127.90 — — 156.85 — 156.85 1.2 6.09 156.85 — — 158.56 — 161.14 1.2 6.21 158.65 — — $ 43.71 $ — $ 161.14 $ 8.3 $ 4.18 $ 107.47 $ 1.8 $ 61.11

Deferred Compensation

Deferred Compensation	12 Months Ended
Deferred Compensation	Dec. 31, 2022
Compensation Related Costs [Abstract]
Deferred Compensation	11. Deferred Compensation We have a Deferred Equity Participation Plan, (which we refer to as the DEPP), which is a non-qualified plan that generally provides for distributions to certain of our key executives when they reach age 62 (or the one-year anniversary of the date of the grant for participants over the age of 61 as of the grant date) or upon or after their actual retirement if later. Under the provisions of the DEPP, we typically contribute cash in an amount approved by the compensation committee to a rabbi trust on behalf of the executives participating in the DEPP, and instruct the trustee to acquire a specified number of shares of our common stock on the open market or in privately negotiated transactions based on participant elections. Distributions under the DEPP may not normally be made until the participant reaches age 62 (or the one-year anniversary of the date of the grant for participants over the age of 61 as of the grant date) and are subject to forfeiture in the event of voluntary termination of employment prior to then. DEPP awards are generally made annually in the first quarter. In addition, we annually make awards under sub-plans of the DEPP for certain production staff, which generally provide for vesting and/or distributions no sooner than five years from the date of awards, although certain awards vest and/or distribute after the earlier of fifteen years or the participant reaching age 65 . All contributions to the plan (including sub-plans) deemed to be invested in shares of our common stock are distributed in the form of our common stock and all other distributions are paid in cash. Our common stock that is issued to or purchased by the rabbi trust as a contribution under the DEPP is valued at historical cost, which equals its fair market value at the date of grant or date of purchase. When common stock is issued, we record an unearned deferred compensation obligation as a reduction of capital in excess of par value in the accompanying consolidated balance sheet, which is amortized to compensation expense ratably over the vesting period of the participants. Future changes in the fair market value of our common stock owed to the participants do not have any impact on the amounts recorded in our consolidated financial statements. In the first quarter of each of 2022, 2021 and 2020, the compensation committee approved $ 26.3 million, $ 17.0 million and $ 14.1 million, respectively, of awards in the aggregate to certain key executives under the DEPP that were contributed to the rabbi trust in the first quarters of 2022, 2021 and 2020, respectively. We contributed cash to the rabbi trust and instructed the trustee to acquire a specified number of shares of our common stock on the open market to fund these 2022, 2021 and 2020 awards. During 2022, 2021 and 2020, we charged $ 18.5 million, $ 14.1 million and $ 12.2 million, respectively, to compensation expense related to these awards. In 2022, 2021 and 2020, the compensation committee approved $ 1.9 million, $ 3.2 million and $ 1.8 million, respectively, of awards under the sub‑plans referred to above, which were contributed to the rabbi trust in first quarter 2022, 2021 and 2020, respectively. During 2022, 2021 and 2020, we charged $ 2.3 million, $ 2.3 million and $ 1.9 million, respectively, to compensation expense related to these awards. There were no distributions from the sub-plans during 2022 and 2021. At December 31, 2022 and 2021, we recorded $ 77.7 million (related to 2.5 million shares) and $ 67.4 million (related to 2.7 million shares), respectively, of unearned deferred compensation as a reduction of capital in excess of par value in the accompanying consolidated balance sheet. The total intrinsic value of our unvested equity based awards under the plan at December 31, 2022 and 2021 was $ 478.7 million and $ 451.0 million, respectively. During 2022, 2021 and 2020, cash and equity awards with an aggregate fair value of $ 45.6 million, $ 19.1 million and $ 41.2 million, respectively, were vested and distributed to executives under the DEPP. We have a Deferred Cash Participation Plan (which we refer to as the DCPP), which is a non-qualified deferred compensation plan for certain key employees, other than executive officers, that generally provides for vesting and/or distributions no sooner than five years from the date of awards. Under the provisions of the DCPP, we typically contribute cash in an amount approved by the compensation committee to the rabbi trust on behalf of the executives participating in the DCPP, and instruct the trustee to acquire a specified number of shares of our common stock on the open market or in privately negotiated transactions based on participant elections. In the first quarter of each of 2022, 2021 and 2020, the compensation committee approved $ 8.3 million, $ 7.2 million and $ 3.0 million, respectively, of awards in the aggregate to certain key executives under the DCPP that were contributed to the rabbi trust in second quarters of 2022, 2021 and 2020, respectively. During 2022, 2021 and 2020 we charged $ 13.4 million, $ 9.6 million and $ 6.9 million to compensation expense related to these awards. There were $ 16.9 million, $ 6.7 million and $ 3.2 million of distributions from the DCPP during 2022, 2021 and 2020, respectively.

Restricted Stock, Performance S

Restricted Stock, Performance Share and Cash Awards	12 Months Ended
Restricted Stock, Performance Share and Cash Awards	Dec. 31, 2022
Text Block [Abstract]
Restricted Stock, Performance Share and Cash Awards	12. Restricted Stock, Performance Share and Cash Awards Restricted Stock Awards As discussed in Note 10 to these consolidated financial statements, on May 10, 2022, our stockholders approved the LTIP, which replaced our previous stockholder-approved 2017 LTIP. The LTIP provides for the grant of a stock award either as restricted stock or as restricted stock units to officers, employees and non-employee directors. In either case, the compensation committee may determine that the award will be subject to the attainment of performance measures over an established performance period. Stock awards and the related dividend equivalents are non-transferable and subject to forfeiture if the holder does not remain continuously employed with us during the applicable restriction period or, in the case of a performance-based award, if applicable performance measures are not attained. The compensation committee will determine all of the terms relating to the satisfaction of performance measures and the termination of a restriction period, or the forfeiture and cancellation of a restricted stock award upon a termination of employment, whether by reason of disability, retirement, death or any other reason. The agreements awarding restricted stock units under the LTIP will specify whether such awards may be settled in shares of our common stock, cash or a combination of shares and cash and whether the holder will be entitled to receive dividend equivalents, on a current or deferred basis, with respect to such award. Prior to the settlement of a restricted stock unit, the holder of a restricted stock unit will have no rights as a stockholder of the company. The maximum number of shares available under the LTIP for restricted stock, restricted stock units and performance unit awards settled with stock (i.e., all awards other than stock options and stock appreciation rights) is 4.0 million. At December 31, 2022 , 3.3 million shares were available for grant under the LTIP for such awards. In 2022, 2021 and 2020, we granted 650,355 , 326,584 and 422,610 restricted stock units, respectively, to employees under the LTIP and 2017 LTIP, with an aggregate fair value of $ 99.4 million, $ 40.1 million and $ 34.9 million, respectively, at the date of grant. The 2022, 2021 and 2020 restricted stock units vest as follows: 641,000 units granted in first quarter 2022, 314,000 units granted in first quarter 2021 and 405,870 units granted in first quarter 2020 vest in full based on continued employment through March 15, 2027 , March 16, 2026 and March 12, 2025 , respectively, while the other 2022, 2021 and 2020 restricted stock unit awards generally vest in full based on continued employment through the vesting period on the anniversary date of the grant. For our executive officers age 55 or older, restricted stock units awarded in 2022, 2021 and 2020 are not subject to forfeiture upon such officers’ departure from the company after two years from the date of grant. The vesting periods of the 2022, 2021 and 2020 restricted stock unit awards are as follows (in actual shares): Restricted Stock Units Granted Vesting Period 2022 2021 2020 One year 9,270 10,105 16,740 Two years — 2,105 8,870 Five years 641,085 314,374 397,000 Total shares granted 650,355 326,584 422,610 We account for restricted stock awards at historical cost, which equals its fair market value at the date of grant, which is amortized to compensation expense ratably over the vesting period of the participants. Future changes in the fair value of our common stock that is owed to the participants do not have any impact on the amounts recorded in our consolidated financial statements. During 2022, 2021 and 2020, we charged $ 36.4 million, $ 26.7 million and $ 23.0 million, respectively, to compensation expense related to restricted stock awards granted in 2011 through 2022. The total intrinsic value of unvested restricted stock at December 31, 2022 and 2021 was $ 401.3 million and $ 331.8 million, respectively. During 2022 and 2021, equity awards (including accrued dividends) with an aggregate fair value of $ 62.0 million and $ 48.9 million were vested and distributed to employees under this plan. Performance Share Awards On March 15, 2022, March 16, 2021 and March 12, 2020, pursuant to the 2017 LTIP, the compensation committee approved 54,000 , 67,000 and 82,500 , respectively of provisional performance share awards, with an aggregate fair value of $ 8.6 million, $ 8.6 million and $ 7.1 million, respectively, for future grants to our officers. Each performance unit award was equivalent to the value of one share of our common stock on the date such provisional award was approved. At the end of the performance period, eligible participants will receive a number of earned shares based on the growth in adjusted EBITDAC per share (as defined in the 2022 Proxy Statement). Earned shares for the 2022, 2021 and 2020 provisional awards will fully vest based on continuous employment through March 15, 2025, March 16, 2024 and March 12, 2023, respectively, and will be settled in unrestricted shares of our common stock on a one‑for‑one basis as soon as practicable thereafter. The 2022, 2021 and 2020 awards are subject to a three-year performance period that begins on January 1, 2022, 2021 and 2020, respectively, and vest on the three-year anniversary of the date of grant (March 15, 2025, March 16, 2024 and March 12, 2023). For certain of our executive officers age 55 or older, awards granted are no longer subject to forfeiture upon such officers’ departure from the company after two years from the date of grant. During 2022, 2021 and 2020, we recognized $ 15.2 million, $ 15.9 million and $ 16.2 million, respectively, to compensation expense related to performance share awards granted in 2018 through 2022. The total intrinsic value of unvested performance share awards at December 31, 2022 and 2021 was $ 62.7 million and $ 64.3 million. During 2022, 2021 and 2020, equity awards (including accrued dividends) with an aggregate fair value of $ 21.8 million, $ 19.1 million and $ 12.5 million was vested and distributed to employees under this plan. Cash Awards On March 15, 2022, pursuant to our Performance Unit Program (which we refer to as the Program), the compensation committee approved provisional cash awards of $ 19.9 million in the aggregate for future grants to our officers and key employees that are denominated in units ( 125,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. The Program consists of a one-year performance period based on our financial performance and a three-year vesting period measured from January 1 of the year of grant. At the discretion of the compensation committee and determined based on our performance, the eligible officer or key employee will be granted a percentage of the provisional cash award units that equates to the EBITDAC growth achieved (as defined in the Program). At the end of the performance period, eligible participants will be granted a number of units based on achievement of the performance goal and subject to approval by the compensation committee. Granted units for the 2022 provisional award will fully vest based on continuous employment through January 1, 2025. The ultimate award value will be equal to the trailing twelve‑month price of our common stock on December 31, 2024, multiplied by the number of units subject to the award, but limited to between 0.5 and 1.5 times the original value of the units determined as of the grant date. The fair value of the awarded units will be paid out in cash as soon as practicable in 2025. If an eligible employee leaves us prior to the vesting date, the entire award will be forfeited. We did no t recognize any compensation expense during the year ended December 31, 2022 related to the 2022 provisional award under the Program. Based on company performance for 2022, we expect to grant 122,000 units under the Program in first quarter 2023 that will fully vest on January 1, 2025 . On March 16, 2021, pursuant to the Program, the compensation committee approved provisional cash awards of $ 18.8 million in the aggregate for future grants to our officers and key employees that are denominated in units ( 147,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. Terms of the 2021 provisional award were similar to the terms of the 2022 provisional awards. Based on our performance for 2021, we granted 143,000 units under the Program in first quarter 2022 that will fully vest on January 1, 2024 . During 2022 we charged $ 12.4 million to compensation expense related to these awards. We did no t recognize any compensation expense during 2021 related to the 2021 provisional award under the Program. On March 12, 2020, pursuant to the Program, the compensation committee approved provisional cash awards of $ 18.4 million in the aggregate for future grants to our officers and key employees that are denominated in units ( 213,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. Terms of the 2020 provisional award were similar to the terms of the 2022 provisional awards. Based on our performance for 2020, we granted 208,000 units under the Program in first quarter 2021 that will fully vest on January 1, 2023 . During 2022 and 2021, we charged $ 12.1 million and $ 12.6 million to compensation expense related to these awards. We did no t recognize any compensation expense during 2020 related to the 2020 provisional award under the Program. On March 14, 2019, pursuant to the Program, the compensation committee approved provisional cash awards of $ 16.5 million in the aggregate for future grants to our officers and key employees that are denominated in units ( 206,800 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. Terms of the 2019 provisional award were similar to the terms of the 2022 provisional awards. Based on our performance for 2019, we granted 200,000 units under the Program in first quarter 2020 that will fully vest on January 1, 2022 . During 2021 and 2020, we charged $ 11.5 million and $ 10.6 million, respectively, to compensation expense related to these awards. We did no t recognize any compensation expense during 2019 related to the 2019 provisional award under the Program. On March 15, 2018, pursuant to the Program, the compensation committee approved provisional cash awards of $ 15.0 million in the aggregate for future grants to our officers and key employees that are denominated in units ( 219,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. Terms of the 2018 provisional award were similar to the terms of the 2019 provisional awards. Based on our performance for 2018, we granted 190,000 units under the Program in first quarter 2019 that fully vested on January 1, 2021 . During 2020 and 2019, we charged $ 9.9 million and $ 8.9 million, respectively, to compensation expense related to these awards. We did no t recognize any compensation expense during 2018 related to the 2018 provisional award under the Program. During 2022, cash awards related to the 2019 provisional awards with an aggregate fair value of $ 21.1 million ( 177,000 units in the aggregate) were vested and distributed to employees under the Program. During 2021, cash awards related to the 2018 provisional awards with an aggregate fair value of $ 17.7 million ( 176,300 units in the aggregate) were vested and distributed to employees under the Program. During 2020, cash awards related to the 2017 provisional award with an aggregate value of $ 18.9 million ( 221,600 units in the aggregate) were vested and distributed to employees under the Program.

Retirement Plans

Retirement Plans	12 Months Ended
Retirement Plans	Dec. 31, 2022
Retirement Benefits [Abstract]
Retirement Plans	13. Retirement Plans We have a noncontributory defined benefit pension plan that, prior to July 1, 2005, covered substantially all of our domestic employees who had attained a specified age and one year of employment. Benefits under the plan were based on years of service and salary history. In 2005, we amended our defined benefit pension plan to freeze the accrual of future benefits for all U.S. employees, effective on July 1, 2005. Since the plan is frozen, there is no difference between the projected benefit obligation and accumulated benefit obligation at December 31, 2022 and 2021. In the table below, the service cost component represents plan administration costs that are incurred directly by the plan. A reconciliation of the beginning and ending balances of the pension benefit obligation and fair value of plan assets and the funded status of the plan is as follows (in millions): Year Ended December 31, 2022 2021 Change in pension benefit obligation: Benefit obligation at beginning of year $ 279.4 $ 290.6 Service cost 0.5 0.5 Interest cost 6.8 6.4 Net actuarial gain ( 58.7 ) ( 2.8 ) Benefits paid ( 16.1 ) ( 15.3 ) Benefit obligation at end of year $ 211.9 $ 279.4 Change in plan assets: Fair value of plan assets at beginning of year $ 282.3 $ 262.8 Actual (loss) return on plan assets ( 53.7 ) 34.8 Contributions by the company — — Benefits paid ( 16.1 ) ( 15.3 ) Fair value of plan assets at end of year $ 212.5 $ 282.3 Funded status of the plan (underfunded) $ 0.6 $ 2.9 Amounts recognized in the consolidated balance sheet Noncurrent assets - accrued benefit liability $ 0.6 $ 2.9 Accumulated other comprehensive income 54.2 42.5 Net amount included in retained earnings $ 54.8 $ 45.4 The components of the net periodic pension benefit cost for the plan and other changes in plan assets and obligations recognized in earnings and other comprehensive earnings consist of the following (in millions): Year Ended December 31, 2022 2021 2020 Net periodic pension cost: Service cost $ 0.5 $ 0.5 $ 0.8 Interest cost on benefit obligation 6.8 6.4 8.0 Expected return on plan assets ( 19.1 ) ( 17.7 ) ( 16.4 ) Amortization of net loss 2.4 5.9 6.2 Net periodic benefit income ( 9.4 ) ( 4.9 ) ( 1.4 ) Other changes in plan assets and obligations recognized Net loss (gain) incurred 14.1 ( 19.9 ) 4.7 Amortization of net loss ( 2.4 ) ( 5.9 ) ( 6.2 ) Total recognized in other comprehensive income (loss) 11.7 ( 25.8 ) ( 1.5 ) Total recognized in net periodic pension cost and other $ 2.3 $ ( 30.7 ) $ ( 2.9 ) The following weighted average assumptions were used at December 31 in determining the plan’s pension benefit obligation: December 31, 2022 2021 Discount rate 5.25 % 2.50 % Weighted average expected long-term rate of return on plan assets 7.00 % 7.00 % The following weighted average assumptions were used at January 1 in determining the plan’s net periodic pension benefit cost: Year Ended December 31, 2022 2021 2020 Discount rate 2.50 % 2.25 % 3.00 % Weighted average expected long-term rate of return on plan assets 7.00 % 7.00 % 7.00 % The following benefit payments are expected to be paid by the plan (in millions): 2023 $ 17.1 2024 17.1 2025 17.3 2026 17.3 2027 17.3 2028 to 2032 81.9 The following is a summary of the plan’s weighted average asset at December 31 by asset category: December 31, Asset Category 2022 2021 Equity securities 62.0 % 60.0 % Debt securities 31.0 % 32.0 % Real estate 7.0 % 8.0 % Total 100.0 % 100.0 % Plan assets are invested in various pooled separate accounts under annuity contracts managed by two life underwriting enterprises. The plan’s investment policy provides that investments will be allocated in a manner designed to provide a long-term investment return greater than the actuarial assumptions, maximize investment return commensurate with risk and to comply with the Employee Income Retirement Security Act of 1974, as amended (which we refer to as ERISA), by investing the funds in a manner consistent with ERISA’s fiduciary standards. The weighted average expected long-term rate of return on plan assets assumption was determined based on a review of the asset allocation strategy of the plan using expected ten-year return assumptions for all of the asset classes in which the plan was invested at December 31, 2022 and 2021. The return assumptions used in the valuation were based on data provided by the plan’s external investment advisors. The following is a summary of the plan’s assets carried at fair value as of December 31 by level within the fair value hierarchy (in millions): December 31, Fair Value Hierarchy 2022 2021 Level 1 $ — $ — Level 2 112.9 158.1 Level 3 99.6 124.2 Total fair value $ 212.5 $ 282.3 The plan’s Level 2 assets consist of ownership interests in various pooled separate accounts within a life insurance carrier’s group annuity contract. The fair value of the pooled separate accounts is determined based on the net asset value of the respective funds, which is obtained from the underwriting enterprise and determined each business day with issuances and redemptions of units of the funds made based on the net asset value per unit as determined on the valuation date. We have not adjusted the net asset values provided by the underwriting enterprise. There are no restrictions as to the plan’s ability to redeem its investment at the net asset value of the respective funds as of the reporting date. The plan’s Level 3 assets consist of pooled separate accounts within another life insurance carrier’s annuity contracts for which fair value has been determined by an independent valuation. Due to the nature of these annuity contracts, our management makes assumptions to determine how a market participant would price these Level 3 assets. In determining fair value, the future cash flows to be generated by the annuity contracts were estimated using the underlying benefit provisions specified in each contract, market participant assumptions and various actuarial and financial models. These cash flows were then discounted to present value using a risk-adjusted rate that takes into consideration market based rates of return and probability-weighted present values. The following is a reconciliation of the beginning and ending balances for the Level 3 assets of the plan measured at fair value (in millions): Year Ended December 31, 2022 2021 Fair value at January 1 $ 124.2 $ 121.0 Settlements ( 1.5 ) ( 15.2 ) Unrealized (loss) gain ( 23.1 ) 18.4 Fair value at December 31 $ 99.6 $ 124.2 We were no t required under the IRC to make any minimum contributions to the plan for each of the 2022, 2021 and 2020 plan years. This level of required funding is based on the plan being frozen and the aggregate amount of our historical funding. During 2022, 2021 and 2020 we did no t make discretionary contributions to the plan. We also have a qualified contributory savings and thrift 401(k) plan covering the majority of our domestic employees. For eligible employees who have met the plan’s age and service requirements to receive matching contributions, we historically have matched 100 % of pre-tax and Roth elective deferrals up to a maximum of 5.0 % of eligible compensation, subject to federal limits on plan contributions and not in excess of the maximum amount deductible for federal income tax purposes. Beginning in 2021, the amount matched by the company will be discretionary and annually determined by management. Employees must be employed and eligible for the plan on the last day of the plan year to receive a matching contribution, subject to certain exceptions enumerated in the plan document. Matching contributions are subject to a five-year graduated vesting schedule and can be funded in cash or company stock. We expensed (net of plan forfeitures) $ 73.8 million, $ 65.7 million and $ 63.6 million related to the plan in 2022, 2021 and 2020, respectively. Our board of directors authorized the use of common stock to fund our 2020 employer matching contributions to the 401(k) plan, which we funded in February 2021. During 2021, our board of directors authorized the 5.0 % employer matching contributions on eligible compensation to the 401(k) plan for the 2021 plan year to be funded with our common stock, which was funded in February 2022. During 2022, our board of directors authorized the 5.0 % employer matching contributions on eligible compensation to the 401(k) plan for the 2022 plan year to be funded with our common stock, which is expected to be funded in February 2023. We also have a nonqualified deferred compensation plan, the Supplemental Savings and Thrift Plan, for certain employees who, due to IRS rules, cannot take full advantage of our matching contributions under the 401(k) plan. The plan permits these employees to annually elect to defer a portion of their compensation until their retirement or a future date. Our matching contributions to this plan (up to a maximum of the lesser of a participant’s elective deferral of base salary, annual bonus and commissions or 5.0 % of eligible compensation, less matching amounts contributed under the 401(k) plan) are also at the discretion of our board of directors. Matching contributions can be funded in cash or company stock. We expensed $ 11.0 million, $ 8.7 million and $ 7.8 million related to contributions made to a rabbi trust maintained under the plan in 2022, 2021 and 2020, respectively. During 2022, our board of directors authorized the 5.0 % employer matching contributions on eligible compensation to the plan for the 2022 plan year to be funded with our common stock, which is expected to be funded in February 2023. The fair value of the assets in the plan’s rabbi trust at December 31, 2022 and 2021, including employee contributions and investment earnings, was $ 578.2 million and $ 606.6 million, respectively, and has been included in other noncurrent assets and the corresponding liability has been included in other noncurrent liabilities in the accompanying consolidated balance sheet. We also have several foreign benefit plans, the largest of which is a defined contribution plan that provides for us to make contributions of 5.0 % of eligible compensation. In addition, the plan allows for voluntary contributions by U.K. employees, which we match 100 %, up to a maximum of an additional 5.0 % of eligible compensation. Net expense for foreign retirement plans amounted to $ 62.9 million, $ 51.8 million and $ 44.3 million in 2022, 2021 and 2020, respectively.

Investments

Investments	12 Months Ended
Investments	Dec. 31, 2022
Equity Method Investments and Joint Ventures [Abstract]
Investments	14. Investments Chem-Mod LLC - At December 31, 2022 , we held a 46.5 % controlling interest in Chem-Mod LLC. Chem‑Mod LLC possesses the exclusive marketing rights, in the U.S. and Canada, for technologies used to reduce emissions created during the combustion of coal. Prior to 2022, the refined coal production plants discussed below, as well as those owned by other unrelated parties, licensed and used Chem-Mod LLC’s proprietary technologies, The Chem-Mod Solution, in the production of refined coal. The Chem‑Mod Solution used a dual injection sorbent system to reduce mercury, sulfur dioxide and other emissions at coal-fired power plants. We believe that the application of The Chem-Mod Solution prior to 2022 qualified for refined coal tax credits under IRC Section 45 when used with refined coal production plants placed in service by December 31, of both 2011 and 2009. Chem-Mod LLC was marketing its technologies principally to coal-fired power plants owned by utility companies, including those utilities that were operating with the IRC Section 45 refined coal production plants in which we hold an investment. Chem-Mod LLC is determined to be a variable interest entity (which we refer to as a VIE). We are the manager (decision maker) of Chem‑Mod LLC and therefore consolidate its operations into our consolidated financial statements. At December 31, 2022, total assets and total liabilities of this VIE included in our consolidated balance sheet were $ 14.8 million and $ 1.1 million, respectively. At December 31, 2021, total assets and total liabilities of this VIE included in our consolidated balance sheet were $ 19.4 million and $ 1.1 million, respectively. For 2022, total revenues and expenses were $ 1.0 million and $ 5.7 million, respectively. For 2021, total revenues and expenses were $ 82.7 million and $ 14.5 million, respectively. We are under no obligation to fund Chem-Mod’s operations in the future. Chem-Mod International LLC - At December 31, 2022 , we held a 31.5 % noncontrolling ownership interest in Chem-Mod International LLC. Chem-Mod International LLC has the rights to market The Chem-Mod Solution in countries other than the U.S. and Canada. Such marketing activity has been limited to date. C-Quest Technology LLC and C-Quest Technologies International LLC (which we refer together as C-Quest) - At December 31, 2022 , we held a noncontrolling 12 % interest in C-Quest’s global entities. C‑Quest possesses rights, information and technology for the reduction of carbon dioxide emissions created by burning fossil fuels. Thus far, C‑Quest’s operations have been limited to laboratory testing. C-Quest is determined to be a VIE, but we do not consolidate this investment into our consolidated financial statements because we are not the primary beneficiary or decision maker. Clean Coal Investments - • We have investments in limited liability companies that own or have owned 35 refined coal production plants which produce refined coal using proprietary technologies owned by Chem-Mod LLC. We believe the production and sale of refined coal at these plants prior to 2022 was qualified to receive refined coal tax credits under IRC Section 45. The 14 plants placed in service prior to December 31, 2009 were eligible to receive tax credits through 2019 and the 21 plants placed in service prior to December 31, 2011 were eligible to receive tax credits through 2021. • As of December 31, 2022: o We have a noncontrolling interest in one plant, which is owned by a limited liability company (which we refer to as a LLC). We have determined that this LLC is a VIE, for which we are not the primary beneficiary and therefore do not consolidate it. At December 31, 2022 , total assets and total liabilities of this VIE were $ 35.3 million and $ 35.3 million, respectively. For 2022, total revenues and expenses of this VIE were zero and $ 0.3 million, respectively. • We and our co-investors each funded our portion of the on-going operations of the limited liability companies in proportion to our investment ownership percentages. Other than our portion of the on-going operational and decommission funding, there are no additional amounts that we are committed to related to funding these investments. Other Investments - At December 31, 2022 , we owned a noncontrolling, minority interest in one startup venture totaling $ 2.2 million, four venture capital funds totaling $ 3.4 million and five certified low-income housing developments with zero carrying value. The low-income housing developments and real estate entities have been determined to be VIEs, but are not required to be consolidated due to our lack of control over their respective operations. At December 31, 2022 , total assets and total liabilities of these VIEs were approximately $ 4.6 million and $ 0.4 million, respectively.

Leases

Leases	12 Months Ended
Leases	Dec. 31, 2022
Leases [Abstract]
Leases	15. Leases We have operating leases primarily related to branch facilities, data centers, sales offices, and agent locations, automobiles and office equipment. Many of our leases include both lease (fixed rent payments) and non-lease components (common-area or other maintenance costs) which are accounted for as a single lease component as we have elected the practical expedient to group lease and non-lease components for all leases. Variable lease payments, such as periodically indexed and/or market adjustments, are presented as lease expense in the period in which they are incurred. Since we did not elect the short-term policy election, we record leases of 12 months or less on the balance sheet. We exclude options to extend or terminate a lease from our recognition as part of our right-of-use assets and lease liabilities until those options are reasonably certain and/or executed. We do not have any material guarantees, options to purchase, or restrictive covenants related to our leases. As our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the lease commencement date in determining the present value of the lease payments. We consider qualitative factors including our derived credit rating, notched adjustments for collateralization, lease term, and, if significant, adjustments to our collateralized rate to borrow in the same currency in which the lease is denominated. The components of lease expense are as follows (in millions): Statement of Earnings Year ended Lease Components Classification December 31, 2022 Operating lease expense Operating expense $ 139.9 Variable lease expense Operating expense 21.7 Sublease income Investment income ( 1.2 ) Total net lease expense $ 160.4 Variable lease cost consist primarily of common-area and other maintenance costs for our lease facilities, as well as variable lease payments related to indexed and/or market adjustments. Our sublease income derives primarily from a few office lease arrangements and we have no significant sublease losses. Year ended Supplemental Cash Flow Information Related to Leases (in millions) December 31, 2022 Cash paid for amounts included in the measurement of Operating cash flows from operating leases $ 121.4 Right-of-use assets obtained in exchange for new $ 102.9 We present all noncash transactions related to adjustments to the lease liability or right-of-use asset as noncash transactions. This includes all noncash charges related to any modification or reassessment events triggering remeasurement. Supplemental balance sheet information related to leases is as follows (in millions, except lease term and discount rate): Lease Components Balance Sheet Classification December 31, 2022 Lease right-of-use assets Right-of-use assets $ 346.7 Other current lease liabilities Accrued compensation and other current liabilities 82.4 Lease liabilities Lease liabilities - noncurrent 300.4 Total lease liabilities $ 382.8 Weighted-average remaining lease term, years 5.4 Weighted-average discount rate 3.3 % Maturities of operating lease liabilities for each of the next five years and thereafter are as follows (in millions): 2023 $ 98.6 2024 84.2 2025 67.7 2026 54.3 2027 41.7 Thereafter 72.6 Total lease payments 419.1 Less interest ( 36.3 ) Total $ 382.8 Our leases have remaining lease terms of 0.1 years to 14.0 years, some of which may include options to extend the leases for up to 20.0 years and some of which may include options to terminate the leases. As of December 31, 2022 , we had $ 22.4 million of additional leases that have not yet commenced. These leases will commence in 2023 with lease terms of 0.5 years to 10.0 years.

Derivatives and Hedging Activit

Derivatives and Hedging Activity	12 Months Ended
Derivatives and Hedging Activity	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Activity	16. Derivatives and Hedging Activity We are exposed to market risks, including changes in foreign currency exchange rates and interest rates. To manage the risk related to these exposures, we enter into various derivative instruments that reduce these risks by creating offsetting exposures. We generally do not enter into derivative transactions for trading or speculative purposes. Foreign Exchange Risk Management We are exposed to foreign exchange risk when we earn revenues, pay expenses, or enter into monetary intercompany transfers denominated in a currency that differs from our functional currency, or other transactions that are denominated in a currency other than our functional currency. We use foreign exchange derivatives, typically forward contracts and options, to reduce our overall exposure to the effects of currency fluctuations on cash flows. These exposures are hedged, on average, for less than three years. Interest Rate Risk Management We enter into various long-term debt agreements. We use interest rate derivatives, typically swaps, to reduce our exposure to the effects of interest rate fluctuations on the forecasted interest rates for up to three years into the future. We have not received or pledged any collateral related to derivative arrangements at December 31, 2022. The notional and fair values of derivatives designated as hedging instruments are as follows at December 31, 2022 and 2021 (in millions): Derivative Assets Derivative Liabilities Notional Balance Sheet Fair Balance Sheet Fair Instrument Amount Classification Value Classification Value At December 31, 2022 Interest rate contracts $ 950.0 Other current assets $ 56.5 Accrued compensation and $ — Other noncurrent assets 56.6 other current liabilities Other noncurrent liabilities — Foreign exchange contracts (1) 113.0 Other current assets 0.8 Accrued compensation and 18.5 14.5 other current liabilities Other noncurrent assets — Other noncurrent liabilities 27.0 Total $ 1,063.0 $ 128.4 $ 45.5 At December 31, 2021 Interest rate contracts $ 1,000.0 Other current assets $ 4.8 Accrued compensation and $ 1.3 Other noncurrent assets 3.4 other current liabilities Other noncurrent liabilities 11.5 Foreign exchange contracts (1) 17.3 Other current assets 4.3 Accrued compensation and 1.3 other current liabilities Other noncurrent assets 4.3 Other noncurrent liabilities 7.2 Total $ 1,017.3 $ 16.8 $ 21.3 (1) Included within foreign exchange contracts at December 31, 2022 were $ 948.8 million of call options offset with $ 948.8 million of put options, and $ 12.4 million of buy forwards offset with $ 125.4 million of sell forwards. Included within foreign exchange contracts at December 31, 2021 were $ 483.8 million of call options offset with $ 483.8 million of put options, and $ 10.5 million of buy forwards offset with $ 27.9 million of sell forwards. Fair values of these hedge contracts are based on observable and unobservable inputs. Observable inputs include all of the following: quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (for example: interest rates and yield curves observable at commonly quoted intervals, implied volatilities, credit spreads) and market-corroborated inputs. Unobservable inputs are used to measure fair value to the extent that relevant observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. The effect of cash flow hedge accounting on accumulated other comprehensive loss were as follows (in millions): Instrument Amount of Amount of Amount of Statement of Earnings Year ended December 31, 2022 Interest rate contracts $ 179.3 $ ( 1.2 ) $ — Interest expense Foreign exchange contracts ( 26.8 ) 6.3 ( 0.1 ) Commission revenue ( 1.1 ) 1.9 Compensation expense ( 0.8 ) 1.4 Operating expense Total $ 152.5 $ 3.2 $ 3.2 Year ended December 31, 2021 Interest rate contracts $ 35.8 $ ( 1.1 ) $ — Interest expense Foreign exchange contracts ( 13.5 ) ( 3.3 ) — Commission revenue ( 0.8 ) 1.0 Compensation expense ( 0.6 ) 0.7 Operating expense Total $ 22.3 $ ( 5.8 ) $ 1.7 (1) During 2022, the amount excluded from the assessment of hedge effectiveness for our foreign exchange contracts recognized in accumulated other comprehensive loss was a gain of $ 0.9 million. We estimate that approximately $ 29.4 million of pretax loss currently included within accumulated other comprehensive income will be reclassified into earnings in the next twelve months.

Commitments, Contingencies and

Commitments, Contingencies and Off-Balance Sheet Arrangements	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Off-Balance Sheet Arrangements	17. Commitments, Contingencies and Off-Balance Sheet Arrangements In connection with our investing and operating activities, we have entered into certain contractual obligations and commitments. See Note 8 to these consolidated financial statements for additional discussion of these obligations and commitments. Our future minimum cash payments, including interest, associated with our contractual obligations pursuant to the Senior Notes, Note purchase agreements, Credit Agreement, Premium Financing Debt Facility, operating leases and purchase commitments at December 31, 2022 were as follows (in millions): Payments Due by Period Contractual Obligations 2023 2024 2025 2026 2027 Thereafter Total Senior Notes $ — $ — $ — $ — $ — $ 1,600.0 $ 1,600.0 Note purchase agreements 250.0 475.0 200.0 640.0 478.0 2,205.0 4,248.0 Credit Agreement 60.0 — — — — — 60.0 Premium Financing Debt Facility 241.9 — — — — — 241.9 Interest on debt 229.0 212.3 197.7 178.8 160.4 1,408.1 2,386.3 Total debt obligations 780.9 687.3 397.7 818.8 638.4 5,213.1 8,536.2 Operating lease obligations 98.6 84.2 67.7 54.3 41.7 72.6 419.1 Less sublease arrangements ( 0.9 ) ( 0.6 ) ( 0.3 ) ( 0.3 ) ( 0.2 ) — ( 2.3 ) Outstanding purchase obligations 117.4 86.8 36.1 16.8 12.3 14.6 284.0 Total contractual obligations $ 996.0 $ 857.7 $ 501.2 $ 889.6 $ 692.2 $ 5,300.3 $ 9,237.0 The amounts presented in the table above may not necessarily reflect our actual future cash funding requirements, because the actual timing of the future payments made may vary from the stated contractual obligation. On December 20, 2022, we signed a definitive agreement to acquire the partnership interests of Buck, for a gross consideration of $ 660.0 million or approximately $ 585.0 million net of agreed seller funded expenses and net working capital. We expect to fund the transaction via free cash flow and short-term borrowings. The transaction is expected to close during the first half of 2023, subject to customary regulatory approvals. Senior Notes, Note Purchase Agreements, Credit Agreement and Premium Financing Debt Facility - See Note 8 to these consolidated financial statements for a summary the amounts outstanding under the Senior Notes, Note purchase agreements, the Credit Agreement and Premium Financing Debt Facility. Operating Lease Obligations - Our corporate segment’s executive offices and certain subsidiary and branch facilities of our brokerage and risk management segments are located in a building we own at 2850 Golf Road, Rolling Meadows, Illinois, where we have approximately 360,000 square feet of space and will accommodate approximately 2,000 employees at peak pre-pandemic capacity. Relating to the development of our corporate headquarters, we expect to receive property tax related credits under a tax-increment financing note from Rolling Meadows and an Illinois state Economic Development for a Growing Economy (which we refer to as EDGE) tax credit. Incentives from these two programs could total between $ 50.0 million and $ 80.0 million over a fifteen‑year period. We have earned approximately $ 41.4 million of EDGE credits from inception in 2017 through December 31, 2022. We generally operate in leased premises at our other locations. Certain of these leases have options permitting renewals for additional periods. In addition to minimum fixed rentals, a number of leases contain annual escalation clauses which are generally related to increases in an inflation index. Total rent expense, including rent relating to cancelable leases and leases with initial terms of less than one year, amounted to $ 176.6 million in 2022, $ 153.4 million in 2021 and $ 154.0 million in 2020. We have leased certain office space to several non-affiliated tenants under operating sublease arrangements. In the normal course of business, we expect that certain of these leases will not be renewed or replaced. We adjust charges for real estate taxes and common area maintenance annually based on actual expenses, and we recognize the related revenues in the year in which the expenses are incurred. These amounts are not included in the minimum future rentals to be received in the contractual obligations table above. Outstanding Purchase Obligations - We typically do not have a material amount of outstanding purchase obligations at any point in time. The amount disclosed in the contractual obligations table above represents the aggregate amount of unrecorded purchase obligations that we had outstanding at December 31, 2022. These obligations represent agreements to purchase goods or services that were executed in the normal course of business. Off-Balance Sheet Commitments - Our total unrecorded commitments associated with outstanding letters of credit, financial guarantees and funding commitments at December 31, 2022 were as follows (in millions): Total Amount of Commitment Expiration by Period Amounts Off-Balance Sheet Commitments 2023 2024 2025 2026 2027 Thereafter Committed Letters of credit $ — $ — $ — $ — $ — $ 13.0 $ 13.0 Financial guarantees 1.4 2.0 0.2 0.1 0.1 — 3.8 Total commitments $ 1.4 $ 2.0 $ 0.2 $ 0.1 $ 0.1 $ 13.0 $ 16.8 Since commitments may expire unused, the amounts presented in the table above do not necessarily reflect our actual future cash funding requirements. See the Off-Balance Sheet Debt section below for a discussion of letters of credit. All of the letters of credit represent multiple year commitments that have annual, automatic renewing provisions and are classified by the latest commitment date. Substantially all of the purchase agreements related to these acquisitions we do contain provisions for potential earnout obligations. For all of our acquisitions made in the period from 2019 to 2022 that contain potential earnout obligations, such obligations are measured at fair value as of the acquisition date and are included on that basis in the recorded purchase price consideration for the respective acquisition. The amounts recorded as earnout payables are primarily based upon estimated future potential operating results of the acquired entities over a two- to three-year period subsequent to the acquisition date. The aggregate amount of the maximum earnout obligations related to these acquisitions was $ 1,946.2 million, of which $ 1,077.3 million was recorded in our consolidated balance sheet as of December 31, 2022 based on the estimated fair value of the expected future payments to be made, of which approximately $ 734.0 million can be settled in cash or stock at our option and $ 343.3 million must be settled in cash. Off-Balance Sheet Debt - Our unconsolidated investment portfolio includes investments in enterprises where our ownership interest is between 1 % and 50 %, in which management has determined that our level of influence and economic interest is not sufficient to require consolidation. As a result, these investments are accounted for under the equity method. None of these unconsolidated investments had any outstanding debt at December 31, 2022 and 2021 that was recourse to us. At December 31, 2022 , we had posted two letters of credit totaling $ 9.2 million in the aggregate, related to our self-insurance deductibles, for which we had a recorded liability of $ 17.4 million. We have an equity investment in a rent-a-captive facility, which we use as a placement facility for certain of our insurance brokerage operations. At December 31, 2022 , we had posted seven letters of credit totaling $ 2.5 million to allow certain of our captive operations to meet minimum statutory surplus requirements plus additional collateral related to premium and claim funds held in a fiduciary capacity, one letter of credit totaling $ 0.8 million for collateral related to claim funds held in a fiduciary capacity by a recent acquisition, and two letter of credit totaling $ 0.5 million as security deposits for a 2015 acquisition’s lease. These letters of credit have never been drawn upon. Our commitments associated with outstanding letters of credit, financial guarantees and funding commitments at December 31, 2022 were as follows (all dollar amounts in table are in millions): Description, Purpose and Trigger Collateral Compensation Maximum Liability Other investments Funding commitment to an equity investment - None None $ — $ — Trigger - Agreed conditions met Other Credit support under letters of credit (LOC) for None None 9.2 17.4 Trigger - We do not reimburse the insurance Credit enhancement under letters of credit for our None Reimbursement of LOC fees 2.5 — Trigger - Dissolution or catastrophic financial Collateral related to claims funds held in a fiduciary None None 0.8 — Trigger - Claim payments are not made Credit support under letters of credit in lieu of security None None 0.5 — Trigger - Lease payments do not get made Financial guarantees of loans to 5 Canadian-based (1) None 0.8 — Trigger - Default on loan payments Financial guarantee of external loan to subsidiary in None None 3.0 — Trigger - Default on loan payments $ 16.8 $ 17.4 (1) The guarantees are collateralized by shares in minority holdings of our Canadian operating companies. Since commitments may expire unused, the amounts presented in the table above do not necessarily reflect our actual future cash funding requirements. Litigation, Regulatory and Taxation Matters - We routinely are involved in legal proceedings, claims, disputes, regulatory matters and governmental inspections or investigations arising in the ordinary course of or incidental to our business, including those noted below in this section. We record accruals in the consolidated financial statements for pending litigation when we determine that an unfavorable outcome is probable and the amount of the loss can be reasonably estimated. For the matters we disclose that do not include an estimate of the amount of loss or range of losses, such an estimate is not possible or is immaterial, and we may be unable to estimate the possible loss or range of losses that could potentially result from the application of non-monetary remedies, unless disclosed below. We currently believe that the ultimate outcome of these proceedings, individually and in the aggregate, will not materially harm our financial position, results of operations or cash flows. However, legal proceedings and government investigations are subject to inherent uncertainties, and unfavorable rulings or other adverse events could occur, including the payment of substantial monetary damages or an injunction or other order prohibiting us from selling one or more products at all or in particular ways, precluding particular business practices or requiring other remedies, which may result in a material adverse impact on our business, results of operations or financial position. During 2022, we received a subpoena from the FCPA Unit of the U.S. Department of Justice seeking information related to our insurance business with public entities in Ecuador. We continue to fully cooperate with the investigation. In July 2019, Midwest Energy Emissions Corp. and MES Inc. (which we refer to together as Midwest Energy) filed a patent infringement lawsuit in the United States District Court for the District of Delaware against us, Chem‑Mod LLC and numerous other related and unrelated parties. The complaint alleges that the named defendants infringe patents held exclusively by Midwest Energy and seeks unspecified damages and injunctive relief. Discovery is complete and the case is scheduled for trial in November 2023. We continue to defend this matter vigorously. As previously disclosed, our IRC 831(b) (or “micro-captive”) advisory services businesses has been under audit by the IRS since 2013. Among other matters, the IRS is investigating whether we have been acting as a tax shelter promoter in connection with these operations. Additionally, the IRS is conducting a criminal investigation related to IRC 831(b) micro-captive underwriting enterprises. We have been advised that we are not a target of the criminal investigation. We are fully cooperating with both matters. Contingent Liabilities - We purchase insurance to provide protection from errors and omissions (which we refer to as E&O) claims that may arise during the ordinary course of business. Currently we retain the first $ 15.0 million of every E&O claim up to $ 15.0 million. In addition, we retain, in aggregate: up to another $ 2.0 million between $ 15.0 million and $ 100.0 million, plus up to another $10 .0 million between $ 100.0 million and $ 225.0 million, and up to another $20 .0 million between $ 225.0 million and $400 .0 million. We have historically maintained self-insurance reserves for the portion of our E&O exposure that is not insured. We periodically determine a range of possible reserve levels using actuarial techniques that rely heavily on projecting historical claim data into the future. Our E&O reserve in the December 31, 2022 consolidated balance sheet is above the lower end of the most recently determined actuarial range by $ 10.0 million and below the upper end of the actuarial range by $ 1.8 million. We can make no assurances that the historical claim data used to project the current reserve levels will be indicative of future claim activity. Thus, the E&O reserve level and corresponding actuarial range could change in the future as more information becomes known, which could materially impact the amounts reported and disclosed herein. Tax-advantaged Investments No Longer Held - Between 1996 and 2007, we developed and then sold portions of our ownership in various energy related investments, many of which qualified for tax credits under IRC Section 29. We recorded tax benefits in connection with our ownership in these investments. At December 31, 2022 , we had exposure on $ 108.0 million of previously earned tax credits. Under the TCJA, a portion of these previously earned tax credits were refunded in 2019 for tax year 2018, according to a specific formula. Under the Coronavirus Act, Relief, and Economic Security Act (the CARES Act), which was passed on March 27, 2020, we accelerated the refund of all remaining credits on April 17, 2020, and the remaining credits were refunded to us in the second quarter of 2020. In 2004, 2007 and 2009, the IRS examined several of these investments and all examinations were closed without any changes being proposed by the IRS. However, any future adverse tax audits, administrative rulings or judicial decisions could disallow previously claimed tax credits. Due to the contingent nature of this exposure and our related assessment of its likelihood, no reserve has been recorded in our December 31, 2022 consolidated balance sheet related to this exposure.

Insurance Operations

Insurance Operations	12 Months Ended
Insurance Operations	Dec. 31, 2022
Insurance [Abstract]
Insurance Operations	18. Insurance Operations We have ownership interests in several underwriting enterprises based in the U.S., Bermuda, Gibraltar, Guernsey, Isle of Man and Malta that primarily operate segregated account “rent-a-captive” facilities. These “rent-a-captive” facilities enable our clients to receive the benefits of owning a captive underwriting enterprise without incurring certain disadvantages of ownership. Captive underwriting enterprises, or “rent-a-captive” facilities, are created for clients to insure their risks and capture any underwriting profit and investment income, which would then be available for use by the insureds, generally to reduce future costs of their insurance programs. In general, these companies are set up as protected cell companies that are comprised of separate cell business units (which we refer to as Captive Cells) and the core regulated company (which we refer to as the Core Company). The Core Company is owned and operated by us and no insurance policies are assumed by the Core Company. All insurance is assumed or written within individual Captive Cells. Only the activity of the supporting Core Company of the rent-a-captive facility is recorded in our consolidated financial statements, including cash and stockholder’s equity of the legal entity and any expenses incurred to operate the rent-a-captive facility. Most Captive Cells reinsure individual lines of insurance coverage from external underwriting enterprises. In addition, some Captive Cells offer individual lines of insurance coverage from one of our underwriting enterprise subsidiaries. The different types of insurance coverage include special property, general liability, products liability, medical professional liability, other liability and medical stop loss. The policies are generally claims-made. Insurance policies are written by an underwriting enterprise and the risk is assumed by each of the Captive Cells. In general, we structure these operations to have no underwriting risk on a net written basis. In situations where we have assumed underwriting risk on a net written basis, we have managed that exposure by obtaining full collateral for the underwriting risk we have assumed from our clients. We typically require pledged assets including cash and/or investment accounts or letters of credit to limit our risk. We have a wholly owned underwriting enterprise subsidiary based in the U.S. that cedes all of its insurance risk to reinsurers or captives under facultative and quota share treaty reinsurance agreements. This company was established in fourth quarter 2014 and began writing business in December 2014. These reinsurance arrangements diversify our business and minimize our exposure to losses or hazards of an unusual nature. The ceding of insurance does not discharge us of our primary liability to the policyholder. In the event that all or any of the reinsuring companies are unable to meet their obligations, we would be liable for such defaulted amounts. Therefore, we are subject to credit risk with respect to the obligations of our reinsurers or captives. In order to minimize our exposure to losses from reinsurer credit risk and insolvencies, we have managed that exposure by obtaining full collateral for which we typically require pledged assets, including cash and/or investment accounts or letters of credit, to fully offset the risk. Reconciliations of direct to net premiums, on a written and earned basis, for 2022, 2021 and 2020 related to the wholly-owned underwriting enterprise subsidiary discussed above are as follows (in millions): 2022 2021 2020 Written Earned Written Earned Written Earned Direct $ 24.4 $ 28.7 $ 30.9 $ 35.9 $ 37.7 $ 40.7 Assumed 0.4 0.2 0.2 0.2 0.1 0.9 Ceded ( 24.8 ) ( 28.9 ) ( 31.1 ) ( 36.1 ) ( 37.8 ) ( 41.6 ) Net $ — $ — $ — $ — $ — $ — At December 31, 2022 and 2021, our underwriting enterprise subsidiary had reinsurance recoverables of $ 20.4 million and $ 28.0 million, respectively, related to liabilities established for ceded unearned premium reserves and loss and loss adjustment expense reserves. These reinsurance recoverables relate to direct and assumed business that has been fully ceded to our reinsurers or captives and have been included in premiums and fees receivables in the accompanying consolidated balance sheet.

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	19. Income Taxes We and our principal domestic subsidiaries are included in a consolidated U.S. federal income tax return. Our international subsidiaries file various income tax returns in their jurisdictions. Significant components of earnings before income taxes and the provision for income taxes are as follows (in millions): Year Ended December 31, 2022 2021 2020 Earnings before income taxes: United States $ 781.6 $ 593.0 $ 524.4 Foreign, principally Australia, Canada, New Zealand 545.4 382.1 346.5 Total earnings before income taxes $ 1,327.0 $ 975.1 $ 870.9 Provision for income taxes: Federal: Current $ 109.1 $ 44.6 $ 43.6 Deferred ( 3.5 ) ( 151.6 ) ( 112.4 ) 105.6 ( 107.0 ) ( 68.8 ) State and local: Current 114.3 50.6 36.6 Deferred ( 83.5 ) ( 11.6 ) ( 19.3 ) 30.8 39.0 17.3 Foreign: Current 196.6 108.8 94.6 Deferred ( 122.0 ) ( 20.7 ) ( 30.3 ) 74.6 88.1 64.3 Total provision for income taxes $ 211.0 $ 20.1 $ 12.8 A reconciliation of the provision for income taxes with the U.S. federal statutory income tax rate is as follows (in millions, except percentages): Year Ended December 31, 2022 2021 2020 Amount % of Pretax Amount % of Pretax Amount % of Pretax Federal statutory rate $ 278.7 21.0 $ 204.8 21.0 $ 182.9 21.0 State income taxes - net of 32.9 2.5 30.7 3.2 22.2 2.6 Differences related to non U.S. operations ( 31.9 ) ( 2.4 ) ( 8.7 ) ( 0.9 ) ( 2.5 ) ( 0.3 ) Alternative energy and other ( 6.9 ) ( 0.5 ) ( 199.0 ) ( 20.4 ) ( 154.3 ) ( 17.7 ) Other permanent differences 22.5 1.7 ( 3.5 ) ( 0.4 ) ( 15.7 ) ( 1.8 ) Stock-based compensation ( 59.3 ) ( 4.5 ) ( 40.0 ) ( 4.1 ) ( 31.4 ) ( 3.6 ) Changes in unrecognized tax benefits 4.0 0.3 0.8 0.1 — — Change in valuation allowance 15.5 1.2 26.4 2.7 6.5 0.7 Change in tax rates ( 44.5 ) ( 3.4 ) 8.6 0.9 5.5 0.6 Other — — — — ( 0.4 ) — Provision for income taxes $ 211.0 $ 15.9 $ 20.1 $ 2.1 $ 12.8 $ 1.5 A reconciliation of the beginning and ending balances of the total amounts of gross unrecognized tax benefits is as follows (in millions): December 31, 2022 2021 Gross unrecognized tax benefits at January 1 $ 11.7 $ 11.2 Increases in tax positions for current year 3.8 2.5 Settlements ( 1.7 ) — Lapse in statute of limitations ( 1.4 ) ( 1.6 ) Increases in tax positions for prior years 3.1 0.1 Decreases in tax positions for prior years ( 2.1 ) ( 0.5 ) Gross unrecognized tax benefits at December 31 $ 13.4 $ 11.7 The total amount of net unrecognized tax benefits that, if recognized, would affect the effective tax rate was $ 12.3 million and $ 10.0 million at December 31, 2022 and 2021, respectively. We accrue interest and penalties related to unrecognized tax benefits in our provision for income taxes. At December 31, 2022 and 2021, we had accrued interest and penalties related to unrecognized tax benefits of $ 3.4 million and $ 3.3 million, respectively. We file income tax returns in the U.S. and in various state, local and foreign jurisdictions. We are routinely examined by tax authorities in these jurisdictions. At December 31, 2022, our corporate returns had been examined by the IRS or the statute had lapsed through calendar year 2018, with the exception of calendar years 2011 through 2012 , which are still under examination by the IRS. In addition, from 2011 forward, various state and foreign jurisdictions remain open. It is reasonably possible that our gross unrecognized tax benefits may change within the next twelve months. However, we believe any changes in the recorded balance would not have a significant impact on our consolidated financial statements. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of our deferred tax assets and liabilities are as follows (in millions): December 31, 2022 2021 Deferred tax assets: Alternative minimum tax and other credit carryforwards $ 772.7 $ 1,074.0 Accrued and unfunded compensation and employee benefits 321.8 265.6 Amortizable intangible assets 69.3 92.7 Compensation expense related to stock options 11.1 5.8 Accrued liabilities 126.6 112.1 Accrued pension liability 3.1 1.5 Investments 2.6 3.1 Net operating loss carryforwards 129.4 32.7 Capital loss carryforwards 8.1 8.9 Lease liabilities 96.5 106.4 Capitalized indirect property costs 394.1 — Hedging instruments — 27.3 Other 4.3 5.0 Total deferred tax assets 1,939.6 1,735.1 Valuation allowance for deferred tax assets ( 135.2 ) ( 154.9 ) Deferred tax assets 1,804.4 1,580.2 Deferred tax liabilities: Nondeductible amortizable intangible assets 433.9 394.7 Investment-related partnerships 6.6 4.6 Depreciable fixed assets 46.5 16.2 Right-of-use assets 88.6 96.9 Hedging instruments 10.7 — Other prepaid items 11.8 8.8 Total deferred tax liabilities 598.1 521.2 Net deferred tax assets $ 1,206.3 $ 1,059.0 At December 31, 2022 and 2021, $ 92.4 million and $ 165.7 million, respectively, have been included in noncurrent liabilities in the accompanying consolidated balance sheet. AMT credits have been utilized or refunded in 2020, due to the CARES Act legislation, general business and other tax credits of $ 757.4 million begin to expire, if not utilized, in 2034 and state credits, net of federal benefit, of $ 14.8 million expire, if not used, by 2027 . Net operating loss carryforwards of $ 129.4 million, related to federal, state and foreign begin to expire, if not utilized in 2023 . We expect the historically favorable trend in earnings before income taxes to continue in the foreseeable future. Valuation allowances have been established for certain foreign intangible assets (including nondeductible amortization and earnout payable expenses) and various net operating loss carryforwards that may not be utilized in the future. There are undistributed earnings of $ 835.1 million and $ 806.0 million at December 31, 2022 and 2021, respectively, of foreign subsidiaries which are considered permanently invested outside of the U.S. The amount of unrecognized deferred tax liability on these undistributed earnings was not material at December 31, 2022 and 2021. There are only select jurisdictions for which the company regards the undistributed earnings as no longer permanently reinvested. We have recognized the deferred tax liability associated with these undistributed earnings during 2022, however, such liability was also not material. Current U.S. tax law requires U.S. shareholders to include in income certain “global intangible low-taxed income” (which we refer to as GILTI) beginning in 2018. Our policy is to include the GILTI income in the future period when the tax arises and we recorded income tax expense on such income in 2022, 2021 and 2020. Current U.S. tax law includes the U.S. Base Erosion and Anti-Abuse Tax (which we refer to as BEAT) beginning in 2018. Based on our analysis, we determined that our base erosion payments do not exceed the threshold for applicability for the years in 2022, 2021 and 2020, and we do not currently anticipate any significant long-term impact from the BEAT in our provision for income taxes in future periods. Deferred Income Taxes - The CARES Act delayed certain payroll tax payments until the years 2021 and 2022. At December 31, 2021, $ 6.5 million, of deferred tax assets have been included due to deferral of payroll taxes, which was reversed in 2022.

Supplemental Disclosures of Cas

Supplemental Disclosures of Cash Flow Information	12 Months Ended
Supplemental Disclosures of Cash Flow Information	Dec. 31, 2022
Cash and Cash Equivalents [Abstract]
Supplemental Disclosures of Cash Flow Information	20. Supplemental Disclosures of Cash Flow Information Year ended December 31, Supplemental disclosures of cash flow information (in millions): 2022 2021 2020 Interest paid $ 240.2 $ 215.7 $ 188.9 Income taxes paid, net 317.6 325.4 113.0 Income taxes paid in the table above were net of AMT credits and $( 28.5 ) million in 2021 due to the CARES Act, $( 20.0 ) million in 2020 due to similar temporary relief measures available globally. The 2021 income taxes paid amount was unfavorably impacted due to payment of the $ 20.0 million of 2020 tax-payment deferrals (as noted in the previous sentence) and also approximately $ 106.0 million of tax payments made in 2021 with regards to tax method changes filed with our 2020 tax returns in the fourth quarter of 2021. Those U.S. federal method changes also affected our 2022 and 2021 estimated tax payments. Also in 2022, we elected to defer the utiliza tion of 2021 and 2022 net operating losses in the U.K. causing additional cash tax payments of $ 28.4 million relating to 2021 and $ 49.0 million relating to 2022. Both the U.S. and U.K. payments would have been made in future periods, and do not represent additional taxes due. The following is a reconciliation of our end of period cash, cash equivalents and restricted cash balances as presented in the consolidated statement of cash flows for the years ended December 31, 2022, 2021 and 2020 (in millions): December 31, 2022 2021 2020 Cash and cash equivalents $ 342.3 $ 402.6 $ 664.6 Restricted cash 4,621.9 4,063.7 2,909.7 Total cash, cash equivalents and restricted cash $ 4,964.2 $ 4,466.3 $ 3,574.3 We have a qualified contributory savings and thrift 401(k) plan covering the majority of our domestic employees. For eligible employees who have met the plan’s age and service requirements to receive matching contributions, we historically have matched 100 % of pre-tax and Roth elective deferrals up to a maximum of 5.0 % of eligible compensation, subject to federal limits on plan contributions and not in excess of the maximum amount deductible for federal income tax purposes. Beginning in 2021, the amount matched by the company will be discretionary and annually determined by management. Employees must be employed and eligible for the plan on the last day of the plan year to receive a matching contribution, subject to certain exceptions enumerated in the plan document. Matching contributions are subject to a five-year graduated vesting schedule and can be funded in cash or company stock. We expensed (net of plan forfeitures) $ 73.8 million, $ 65.7 million and $ 63.6 million related to the plan in 2022, 2021 and 2020, respectively. During 2021, our board of directors authorized the 5.0 % employer matching contributions on eligible compensation to the 401(k) plan for the 2021 plan year to be funded with our common stock, which was funded in February 2022. During 2022, our board of directors authorized the 5.0 % employer matching contributions on eligible compensation to the 401(k) plan for the 2022 plan year to be funded with our with our common stock, which is expected to be funded in February 2023.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
Accumulated Other Comprehensive Loss	Dec. 31, 2022
Equity [Abstract]
Accumulated Other Comprehensive Loss	21. Accumulated Other Comprehensive Loss The after-tax components of our accumulated comprehensive loss attributable to controlling interests consist of the following (in millions): Pension Foreign Fair Value Accumulated Balance as of January 1, 2020 $ ( 56.5 ) $ ( 674.8 ) $ ( 28.3 ) $ ( 759.6 ) Net change in period 0.4 183.7 ( 68.1 ) 116.0 Balance as of December 31, 2020 ( 56.1 ) ( 491.1 ) ( 96.4 ) ( 643.6 ) Net change in period 19.0 ( 122.3 ) 20.8 ( 82.5 ) Balance as of December 31, 2021 ( 37.1 ) ( 613.4 ) ( 75.6 ) ( 726.1 ) Net change in period ( 12.3 ) ( 511.8 ) 109.8 ( 414.3 ) Balance as of December 31, 2022 $ ( 49.4 ) $ ( 1,125.2 ) $ 34.2 $ ( 1,140.4 ) The foreign currency translation in 2022, 2021 and 2020 relates to the net impact of changes in the value of the local currencies relative to the U.S. dollar for our operations in the U.K., Australia, Canada, New Zealand, the Caribbean, India and other non-U.S. locations. The reporting currency for our financial statements is the U.S. dollar. Certain of our assets, liabilities, expenses and revenues are denominated in currencies other than the U.S. dollar, primarily the British pound, Australian dollar, Canadian dollar, and New Zealand dollar. To prepare our consolidated financial statements, we must translate those assets, liabilities, expenses and revenues into U.S. dollars at the applicable exchange rates. Assets and liabilities of non-U.S. dollar functional currency operations are translated into U.S. dollars at end-of-period exchange rates while revenues, expenses and cash flows are translated at average monthly exchange rates over the period. Equity is translated at historical exchange rates and the resulting cumulative translation adjustments are included as a component of accumulated other comprehensive loss in the consolidated balance sheet. The net change in the foreign currency translation during 2022 primarily relates to goodwill (see Note 7 to these consolidated financial statements for the impact on goodwill) and amortizable intangible assets held by operations with a non-U.S. dollar functional currency. During 2022, 2021 and 2020, $ 2.2 million, $ 5.8 million and $ 6.1 million, respectively, of expense related to the pension liability was reclassified from accumulated other comprehensive loss to compensation expense in the statement of earnings. During 2022, 2021 and 2020, $ 3.2 million of income, $ 5.8 million of expense and $ 6.3 million of expense, respectively, related to the fair value of derivative investments, was reclassified from accumulated other comprehensive loss to the statement of earnings. During 2022, 2021 and 2020, no amounts related to foreign currency translation were reclassified from accumulated other comprehensive loss to the statement of earnings.

Segment Information

Segment Information	12 Months Ended
Segment Information	Dec. 31, 2022
Segment Reporting [Abstract]
Segment Information	22. Segment Information We have three reportable segments: brokerage, risk management and corporate. The brokerage segment is primarily comprised of our retail and wholesale insurance and reinsurance brokerage operations. The brokerage segment (which comprises our retail P/C, wholesale, reinsurance, benefits and captive operations) generates revenues through commissions paid by underwriting enterprises and through fees charged to our clients. Our brokers, agents and administrators act as intermediaries between underwriting enterprises and our clients and we do not assume net underwriting risks. The risk management segment provides contract claim settlement and administration services for enterprises and public entities that choose to self-insure some or all of their property/casualty coverages and for underwriting enterprises that choose to outsource some or all of their property/casualty claims departments. These operations also provide claims management, loss control consulting and insurance property appraisal services. Revenues are principally generated on a negotiated per-claim or per-service fee basis. Our risk management segment also provides risk management consulting services that are recognized as the services are delivered. The corporate segment manages our clean energy and other investments. In addition, the corporate segment reports the financial information related to our debt and other corporate costs, external acquisition-related expenses and the impact of foreign currency translation. Allocations of investment income and certain expenses are based on reasonable assumptions and estimates primarily using revenue, headcount and other information. We allocate the provision for income taxes to the brokerage and risk management segments using the local country statutory rates. Reported operating results by segment would change if different methods were applied. Financial information relating to our segments for 2022, 2021 and 2020 is as follows (in millions): Year Ended December 31, 2022 Brokerage Risk Corporate Total Revenues: Commissions $ 5,187.4 $ — $ — $ 5,187.4 Fees 1,476.9 1,090.8 — 2,567.7 Supplemental revenues 284.7 — — 284.7 Contingent revenues 207.3 — — 207.3 Investment income 135.4 0.9 — 136.3 Net gains on divestitures 12.1 0.9 — 13.0 Revenue from clean coal activities — — 23.0 23.0 Other net income — — 0.7 0.7 Revenues before reimbursements 7,303.8 1,092.6 23.7 8,420.1 Reimbursements — 130.5 — 130.5 Total revenues 7,303.8 1,223.1 23.7 8,550.6 Compensation 4,024.7 664.9 110.2 4,799.8 Operating 1,039.9 233.9 57.1 1,330.9 Reimbursements — 130.5 — 130.5 Cost of revenues from clean coal activities — — 22.9 22.9 Interest — — 256.9 256.9 Depreciation 103.6 37.8 3.3 144.7 Amortization 448.7 6.2 — 454.9 Change in estimated acquisition earnout payables 90.4 ( 7.4 ) — 83.0 Total expenses 5,707.3 1,065.9 450.4 7,223.6 Earnings (loss) before income taxes 1,596.5 157.2 ( 426.7 ) 1,327.0 Provision (benefit) for income taxes 394.7 41.4 ( 225.1 ) 211.0 Net earnings (loss) 1,201.8 115.8 ( 201.6 ) 1,116.0 Net earnings (loss) attributable to noncontrolling interests 4.4 — ( 2.6 ) 1.8 Net earnings (loss) attributable to controlling interests $ 1,197.4 $ 115.8 $ ( 199.0 ) $ 1,114.2 Net foreign exchange gain $ 2.6 $ 31.4 $ — $ 34.0 Revenues: United States $ 4,503.9 $ 1,029.6 $ 23.7 $ 5,557.2 United Kingdom 1,544.3 44.1 — 1,588.4 Australia 281.8 129.1 — 410.9 Canada 356.0 5.9 — 361.9 New Zealand 166.9 14.4 — 181.3 Other foreign 450.9 — — 450.9 Total revenues $ 7,303.8 $ 1,223.1 $ 23.7 $ 8,550.6 At December 31, 2022 Identifiable assets: United States $ 17,827.2 $ 914.4 $ 2,560.2 $ 21,301.8 United Kingdom 9,486.6 115.9 — 9,602.5 Australia 1,797.9 89.0 — 1,886.9 Canada 1,476.4 4.4 — 1,480.8 New Zealand 731.0 18.8 — 749.8 Other foreign 3,886.0 — — 3,886.0 Total identifiable assets $ 35,205.1 $ 1,142.5 $ 2,560.2 $ 38,907.8 Goodwill - net $ 9,358.1 $ 112.2 $ 19.1 $ 9,489.4 Amortizable intangible assets - net 3,325.9 46.2 — 3,372.1 Year Ended December 31, 2021 Brokerage Risk Corporate Total Revenues: Commissions $ 4,132.3 $ — $ — $ 4,132.3 Fees 1,296.9 967.2 — 2,264.1 Supplemental revenues 248.7 — — 248.7 Contingent revenues 188.0 — — 188.0 Investment income 82.8 0.3 — 83.1 Net gains on divestitures 18.8 0.1 — 18.9 Revenue from clean coal activities — — 1,140.8 1,140.8 Other net revenues — — 0.5 0.5 Revenues before reimbursements 5,967.5 967.6 1,141.3 8,076.4 Reimbursements — 133.0 — 133.0 Total revenues 5,967.5 1,100.6 1,141.3 8,209.4 Compensation 3,252.4 580.7 94.4 3,927.5 Operating 757.9 209.8 104.7 1,072.4 Reimbursements — 133.0 — 133.0 Cost of revenues from clean coal activities — — 1,173.2 1,173.2 Interest — — 226.1 226.1 Loss on extinguishment of debt — — 16.2 16.2 Depreciation 87.8 46.2 17.2 151.2 Amortization 407.6 7.5 — 415.1 Change in estimated acquisition earnout payables 116.3 3.3 — 119.6 Total expenses 4,622.0 980.5 1,631.8 7,234.3 Earnings (loss) before income taxes 1,345.5 120.1 ( 490.5 ) 975.1 Provision (benefit) for income taxes 328.9 30.6 ( 339.4 ) 20.1 Net earnings (loss) 1,016.6 89.5 ( 151.1 ) 955.0 Net earnings attributable to noncontrolling interests 8.4 — 39.8 48.2 Net earnings (loss) attributable to controlling interests $ 1,008.2 $ 89.5 $ ( 190.9 ) $ 906.8 Net foreign exchange loss $ ( 1.7 ) $ — $ ( 0.6 ) $ ( 2.3 ) Revenues: United States $ 3,804.8 $ 910.7 $ 1,141.3 $ 5,856.8 United Kingdom 1,199.0 46.0 — 1,245.0 Australia 252.6 123.5 — 376.1 Canada 302.2 5.8 — 308.0 New Zealand 162.4 14.6 — 177.0 Other foreign 246.5 — — 246.5 Total revenues $ 5,967.5 $ 1,100.6 $ 1,141.3 $ 8,209.4 At December 31, 2021 Identifiable assets: United States $ 15,548.3 $ 790.7 $ 2,489.6 $ 18,828.6 United Kingdom 8,251.3 134.1 — 8,385.4 Australia 1,684.2 84.7 — 1,768.9 Canada 1,436.1 4.4 — 1,440.5 New Zealand 754.5 20.5 — 775.0 Other foreign 2,146.6 — — 2,146.6 Total identifiable assets $ 29,821.0 $ 1,034.4 $ 2,489.6 $ 33,345.0 Goodwill - net $ 8,544.6 $ 100.9 $ 20.7 $ 8,666.2 Amortizable intangible assets - net 3,906.1 47.9 — 3,954.0 Year Ended December 31, 2020 Brokerage Risk Corporate Total Revenues: Commissions $ 3,591.9 $ — $ — $ 3,591.9 Fees 1,136.9 821.0 — 1,957.9 Supplemental revenues 221.9 — — 221.9 Contingent revenues 147.0 — — 147.0 Investment income 75.2 0.7 — 75.9 Net losses on divestitures ( 5.8 ) — — ( 5.8 ) Revenue from clean coal activities — — 863.5 863.5 Other net losses — — ( 0.4 ) ( 0.4 ) Revenues before reimbursements 5,167.1 821.7 863.1 6,851.9 Reimbursements — 151.7 — 151.7 Total revenues 5,167.1 973.4 863.1 7,003.6 Compensation 2,882.5 517.5 66.5 3,466.5 Operating 687.2 162.6 56.7 906.5 Reimbursements — 151.7 — 151.7 Cost of revenues from clean coal activities — — 882.1 882.1 Interest — — 196.4 196.4 Depreciation 73.5 49.4 22.2 145.1 Amortization 411.3 6.0 — 417.3 Change in estimated acquisition earnout payables ( 29.7 ) ( 3.2 ) — ( 32.9 ) Total expenses 4,024.8 884.0 1,223.9 6,132.7 Earnings (loss) before income taxes 1,142.3 89.4 ( 360.8 ) 870.9 Provision (benefit) for income taxes 276.3 22.5 ( 286.0 ) 12.8 Net earnings (loss) 866.0 66.9 ( 74.8 ) 858.1 Net earnings attributable to noncontrolling interests 4.9 — 34.4 39.3 Net earnings (loss) attributable to controlling interests $ 861.1 $ 66.9 $ ( 109.2 ) $ 818.8 Net foreign exchange loss $ ( 2.6 ) $ ( 0.1 ) $ ( 0.2 ) $ ( 2.9 ) Revenues: United States $ 3,369.4 $ 816.4 $ 863.1 $ 5,048.9 United Kingdom 993.7 40.7 — 1,034.4 Australia 216.1 98.4 — 314.5 Canada 243.8 5.3 — 249.1 New Zealand 141.8 12.6 — 154.4 Other foreign 202.3 — — 202.3 Total revenues $ 5,167.1 $ 973.4 $ 863.1 $ 7,003.6 At December 31, 2020 Identifiable assets: United States $ 8,897.9 $ 716.2 $ 2,172.2 $ 11,786.3 United Kingdom 6,135.1 139.2 — 6,274.3 Australia 1,373.3 89.6 — 1,462.9 Canada 1,053.6 4.8 — 1,058.4 New Zealand 766.0 24.1 — 790.1 Other foreign 959.4 — — 959.4 Total identifiable assets $ 19,185.3 $ 973.9 $ 2,172.2 $ 22,331.4 Goodwill - net $ 6,053.6 $ 70.5 $ 2.9 $ 6,127.0 Amortizable intangible assets - net 2,376.3 23.6 — 2,399.9

Schedule II. Valuation and Qual

Schedule II. Valuation and Qualifying Accounts	12 Months Ended
Schedule II. Valuation and Qualifying Accounts	Dec. 31, 2022
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II. Valuation and Qualifying Accounts	Schedu le II Arthur J. Gallagher & Co. Valuation and Qualifying Accounts Balance at Amounts Adjustments Balance at (In millions) Year ended December 31, 2022 Allowance for doubtful accounts $ 8.3 $ 6.8 $ ( 4.0 ) (1) $ 11.1 Allowance for estimated policy cancellations 10.0 2.4 ( 3.1 ) (2) 9.3 Valuation allowance for deferred tax assets 154.9 ( 19.7 ) — 135.2 Accumulated amortization of expiration lists, non-compete agreements and trade names 2,924.0 454.9 ( 78.9 ) (3) 3,300.0 Year ended December 31, 2021 Allowance for doubtful accounts $ 10.1 $ 7.0 $ ( 8.8 ) (1) $ 8.3 Allowance for estimated policy cancellations 9.9 ( 1.3 ) 1.4 (2) 10.0 Valuation allowance for deferred tax assets 94.9 60.0 — 154.9 Accumulated amortization of expiration lists, non-compete agreements and trade names 2,537.0 415.1 ( 28.1 ) (3) 2,924.0 Year ended December 31, 2020 Allowance for doubtful accounts $ 8.7 $ 6.6 $ ( 5.2 ) (1) $ 10.1 Allowance for estimated policy cancellations 8.3 4.1 ( 2.5 ) (2) 9.9 Valuation allowance for deferred tax assets 80.5 14.4 — 94.9 Accumulated amortization of expiration lists, non-compete agreements and trade names 2,087.5 417.3 32.2 (3) 2,537.0 (1) Net activity of bad debt write offs and recoveries and acquired businesses. (2) Additions to allowance related to acquired businesses. (3) Elimination of fully amortized expiration lists, non-compete agreements and trade names, intangible asset/amortization reclassifications and disposal of acquired businesses.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2022
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Arthur J. Gallagher & Co. and its subsidiaries, collectively referred to herein as we, our, us or the company, provide insurance brokerage, consulting and third party claims settlement and administration services to both domestic and international entities. We have three reportable segments: brokerage, risk management and corporate. Our brokers, agents and administrators act as intermediaries between underwriting enterprises and our clients. Our brokerage segment operations provide brokerage and consulting services to companies and entities of all types, including commercial, not-for-profit, public entities, and, to a lesser extent, individuals, in the areas of insurance and reinsurance placements, risk of loss management and management of employer sponsored benefit programs. Our risk management segment operations provide contract claim settlement, claim administration, loss control services and risk management consulting for commercial, not‑for‑profit, captive and public entities, and various other organizations that choose to self-insure property/casualty coverages or choose to use a third-party claims management organization rather than the claim services provided by underwriting enterprises. The corporate segment reports the financial information related to our debt and other corporate costs, legacy clean energy investments, external acquisition‑related expenses and the impact of foreign currency translation. Legacy clean energy investments consist of our investments in limited liability companies that own or have owned 35 commercial clean coal production facilities that produced refined coal using Chem-Mod LLC’s proprietary technologies. We believe these operations produced refined coal that qualifies for tax credits under IRC Section 45. We do not assume underwriting risk on a net basis, other than with respect to de minimis amounts necessary to provide minimum or regulatory capital insurance to organize captives, pools, specialized underwriters or risk-retention groups. Rather, capital necessary for covering losses is provided by underwriting enterprises. Investment income and other revenues are primarily generated from our premium financing operations, our invested cash and restricted cash we hold on behalf of our clients, as well as clean energy investments. In addition, our share of the net earnings related to partially owned entities that are accounted for using the equity method is included in investment income. Arthur J. Gallagher & Co., a global insurance brokerage, risk management and consulting services firm, is headquartered in Rolling Meadows, Illinois. Gallagher provides these services in approximately 130 countries around the world through its owned operations and a network of correspondent brokers and consultants.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include our accounts and all of our majority-owned subsidiaries ( 50 % or greater ownership). Substantially all of our investments in partially owned entities in which our ownership is less than 50 % are accounted for using the equity method based on the legal form of our ownership interest and the applicable ownership percentage of the entity. However, in situations where a less than 50 %-owned investment has been determined to be a VIE and we are deemed to be the primary beneficiary in accordance with the variable interest model of consolidation, we will consolidate the investment into our consolidated financial statements. For partially owned entities accounted for using the equity method, our share of the net earnings of these entities is included in consolidated net earnings. All material intercompany accounts and transactions have been eliminated in consolidation. In the preparation of our consolidated financial statements as of December 31, 2022 , management evaluated all material subsequent events or transactions that occurred after the balance sheet date through the date on which the financial statements were issued for potential recognition and/or disclosure in the notes therein.
Use of Estimates	Use of Estimates The preparation of our consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. These accounting principles require us to make estimates and assumptions that affect the reported amounts of assets and liabilities and revenues and expenses, and the disclosure of contingent assets and liabilities at the date of our consolidated financial statements. We periodically evaluate our estimates and assumptions, including those relating to the valuation of goodwill and other intangible assets, right-of-use assets, investments (including our IRC Section 45 investments), income taxes, revenue recognition, deferred costs, stock-based compensation, claims handling obligations, retirement plans, litigation and contingencies. We base our estimates on historical experience and various assumptions that we believe to be reasonable based on specific circumstances. Such estimates and assumptions could change in the future as more information becomes known, which could impact the amounts reported and disclosed herein.
Revenue Recognition	Revenue Recognition Our revenues are derived from commissions and fees as primarily specified in a written contract, or unwritten business understanding, with our clients or underwriting enterprises. We also recognize investment income over time from our invested assets and invested assets we hold on behalf of our clients or underwriting enterprises.
Brokerage Segment	BROKERAGE SEGMENT Our brokerage segment generates revenues by: (i) Identifying, negotiating and placing all forms of insurance or reinsurance coverage, as well as providing risk-shifting, risk-sharing and risk-mitigation consulting services, principally related to property/casualty, life, health, welfare and disability insurance. We also provide these services through, or in conjunction with, other unrelated agents and brokers, consultants and management advisors; (ii) Acting as an agent or broker for multiple underwriting enterprises by providing services such as sales, marketing, selecting, negotiating, underwriting, servicing and placing insurance coverage on their behalf; (iii) Providing consulting services related to health and welfare benefits, voluntary benefits, executive benefits, compensation, retirement planning, institutional investment and fiduciary, actuarial, compliance, private insurance exchange, human resource technology, communications and benefits administration; and (iv) Providing management and administrative services to captives, pools, risk-retention groups, healthcare exchanges, small underwriting enterprises, such as accounting, claims and loss processing assistance, feasibility studies, actuarial studies, data analytics and other administrative services. The vast majority of our brokerage contracts and service understandings are for a period of one year or less . Commissions and fees The primary source of revenues for our brokerage services is commissions from underwriting enterprises, based on a percentage of premiums paid by our clients, or fees received from clients based on an agreed level of service usually in lieu of commissions. These commissions and fees revenues are substantially recognized at a point in time on the effective date of the associated policies when control of the policy transfers to the client, as well as deferring certain revenues to reflect delivery of services over the contract period. Commissions are fixed at the contract effective date and generally are based on a percentage of premiums for insurance coverage or employee headcount for employer sponsored benefit plans. Commissions depend upon a large number of factors, including the type of risk being placed, the particular underwriting enterprise’s demand, the expected loss experience of the particular risk of coverage, and historical benchmarks surrounding the level of effort necessary for us to place and service the insurance contract. Rather than being tied to the amount of premiums, fees are most often based on an expected level of effort to provide our services. Whether we are paid a commission or a fee, the vast majority of our services are associated with the placement of an insurance (or insurance-like) contract. Accordingly, we recognize approximately 80 % of our commission and fee revenues on the effective date of the underlying insurance contract. The amount of revenue we recognize is based on our costs to provide our services up and through that effective date, including an appropriate estimate of our profit margin on a portfolio basis (a practical expedient as defined in Topic 606). Based on the proportion of additional services we provide in each period after the effective date of the insurance contract, including an appropriate estimate of our profit margin, we recognize approximately 15 % of our commission and fee revenues in the first three months, and the remaining 5 % thereafter. These periods may be different than the underlying premium payment patterns of the insurance contracts, but the vast majority of our services are fully provided within one year of the insurance contract effective date. For consulting and advisory services, we recognize our revenue in the period in which we provide the service or advice. For management and administrative services, our revenue is recognized ratably over the contract period consistent with the performance of our obligations, mostly over an annual term. Supplemental revenues Certain underwriting enterprises may pay us additional revenues for the volume of premium placed with them and for insights into our sales pipeline, our sales capabilities or our risk selection knowledge. These amounts are in excess of the commission and fee revenues discussed above, and not all business we place with underwriting enterprises is eligible for supplemental revenues. Unlike contingent revenues, discussed below, these revenues are primarily a fixed amount or fixed percentage of premium of the underlying eligible insurance contracts. For supplemental revenue contracts based on a fixed percentage of premium, our obligation to the underwriting enterprise is substantially completed upon the effective date of the underlying insurance contract and revenue is fully earned at that time. For supplemental revenue contracts based on a fixed amount, revenue is recognized ratably over the contract period consistent with the performance of our obligations, almost always over an annual term. We receive these revenues on a quarterly or annual basis. Contingent revenues Certain underwriting enterprises may pay us additional revenues for our sales capabilities, our risk selection knowledge, or our administrative efficiencies. These amounts are in excess of the commission or fee revenues discussed above, and not all business we place with participating underwriting enterprises is eligible for contingent revenues. Unlike supplemental revenues, also discussed above, these revenues are variable, generally based on growth, the loss experience of the underlying insurance contracts, and/or our efficiency in processing the business. We generally operate under calendar year contracts, but we do not receive these revenues from the underwriting enterprises until the following calendar year, generally in the first and second quarters, after verification of the performance indicators outlined in the contracts. Accordingly, during each reporting period, we must make our best estimate of amounts we have earned using historical averages and other factors to project such revenues. We base our estimates each period on a contract-by-contract basis where available. In certain cases, it is impractical to assess a very large number of smaller contingent revenue contracts, so we use a historical portfolio estimate in aggregate (a practical expedient as defined in Topic 606). Because our expectation of the ultimate contingent revenue amounts to be earned can vary from period to period, especially in contracts sensitive to loss ratios, our estimates might change significantly from quarter to quarter. For example, in circumstances where our revenues are dependent on a full calendar year loss ratio, adverse loss experience in the fourth quarter could not only negate revenue earnings in the fourth quarter, but also trigger the need to reverse revenues previously recognized during the prior quarters. Variable consideration is recognized when we conclude, based on all the facts and information available at the reporting date, that it is probable that a significant revenue reversal will not occur in future periods. Sub-brokerage costs Sub-brokerage costs are excluded from our gross revenues in our determination of total revenues. Sub-brokerage cost represents commissions paid to sub-brokers related to the placement of certain business by our brokerage segment operations. We recognize this contra revenue in the same manner as the commission revenue to which it relates.
Risk Management Segment	RISK MANAGEMENT SEGMENT Revenues for our risk management segment are comprised of fees generally negotiated (i) on a per-claim or per-service basis, (ii) on a cost‑plus basis, or (iii) as performance-based fees. We also provide risk management consulting services that are recognized as the services are delivered. Per-claim or per-service fees Where we operate under a contract with our fee established on a per-claim or per-service basis, our obligation is to process claims for a term specified within the contract. Because it is impractical to recognize our revenues on an individual claim-by-claim basis, we recognize revenue plus an appropriate estimate of our profit margin on a portfolio basis by grouping claims with similar characteristics (a practical expedient as defined in Topic 606). We apply actuarially-determined, historical-based patterns to determine our future service obligations, without applying a present value discount. Cost-plus fees Where we provide services and generate revenues on a cost-plus basis, we recognize revenue over the contract period consistent with the performance of our obligations. Performance-based fees Certain clients pay us additional fee revenues for our efficiency in managing claims or on the basis of claim outcome effectiveness. These amounts are in excess of the fee revenues discussed above. These revenues are variable, generally based on performance metrics set forth in the underlying contracts. We generally operate under multi-year contracts with fiscal year measurement periods. We do not receive these fees, if earned, until the following year after verification of the performance metrics outlined in the contracts. Each period we base our estimates on a contract-by-contract basis. We must make our best estimate of amounts we have earned using historical averages and other factors to project such revenues. Variable consideration is recognized when we conclude that it is probable that a significant revenue reversal will not occur in future periods. Reimbursements Reimbursements represent amounts received from clients reimbursing us for certain third-party costs associated with providing our claims management services. In certain service partner relationships, we are considered a principal because we direct the third party, control the specified service and combine the services provided into an integrated solution. Given this principal relationship, we are required to recognize revenue gross and service partner vendor fees in the operating expense in our consolidated statement of earnings.
Deferred Costs	Deferred Costs We incur costs to provide brokerage and risk management services. Those costs are either (i) costs to obtain a contract or (ii) costs to fulfill such contract, or (iii) all other costs. (i) Costs to obtain - we incur costs to obtain a contract with a client. Those costs would not have been incurred if the contract had not been obtained. Almost all of our costs to obtain are incurred prior to, or on, the effective date of the contract and consist primarily of incentive compensation we pay to our production employees. Our costs to obtain are expensed as incurred as described in Note 4 to these consolidated financial statements. (ii) Costs to fulfill - we incur costs to fulfill a contract (or anticipated contract) with a client. Those costs are incurred prior to the effective date of the contract and relate to fulfilling our primary placement obligations to our clients. Our costs to fulfill prior to the effective date are capitalized and amortized on the effective date. These fulfillment activities include collecting underwriting information from our client, assessing their insurance needs and negotiating their placement with one or more underwriting enterprises. The majority of costs that we incur relate to compensation and benefits of our client service employees. Costs incurred during preplacement activities are expected to be recovered in the future. If the capitalized costs are no longer deemed to be recoverable, then they would be expensed. (iii) Other costs that are not costs to obtain or fulfill are expensed as incurred. Examples include other operating costs such as rent, utilities, management costs, overhead costs, legal and other professional fees, technology costs, insurance related costs, communication and advertising, and travel and entertainment. Depreciation, amortization and change in estimated acquisition earnout payable are expensed as incurred.
Investment Income	Investment Income Investment income primarily includes interest and dividend income (including interest income from our premium financing operations), which is accrued as it is earned. Net gains on divestitures represent one-time gains related to sales of brokerage related businesses, which are primarily recognized on a cash received basis. Revenues from clean coal activities include revenues from consolidated clean coal production plants, royalty income from clean coal licenses and income (loss) related to unconsolidated clean coal production plants, all of which are recognized as earned. Revenues from consolidated clean coal production plants represent sales of refined coal. Royalty income from clean coal licenses represents fee income related to the use of clean coal technologies. Income (loss) from unconsolidated clean coal production plants includes losses related to our equity portion of the pretax results of the clean coal production plants.
Earnings per Share	Earnings per Share Basic net earnings per share is computed by dividing net earnings by the weighted average number of common shares outstanding during the reporting period. Diluted net earnings per share is computed by dividing net earnings by the weighted average number of common and common equivalent shares outstanding during the reporting period. Common equivalent shares include incremental shares from dilutive stock options, which are calculated from the date of grant under the treasury stock method using the average market price for the period.
Cash and Cash Equivalents	Cash and Cash Equivalents Short-term investments, consisting principally of cash and money market accounts that have average maturities of 90 days or less, are considered cash equivalents.
Restricted Cash	Restricted Cash In our capacity as an insurance broker, we collect premiums from insureds and, after deducting our commissions and/or fees, remit these premiums to underwriting enterprises. We hold unremitted insurance premiums in a fiduciary capacity until we disburse them, and the use of such funds is restricted by laws in certain states and foreign jurisdictions in which our subsidiaries operate. Various state and foreign agencies regulate insurance brokers and provide specific requirements that limit the type of investments that may be made with such funds. Accordingly, we invest these funds in cash and U.S. Treasury fund accounts. We can earn interest income on these unremitted funds, which is included in investment income in the accompanying consolidated statement of earnings. These unremitted amounts are reported as restricted cash in the accompanying consolidated balance sheet, with the related liability reported as premiums payable to underwriting enterprises. Additionally, several of our foreign subsidiaries are required by various foreign agencies to meet certain liquidity and solvency requirements. We were in compliance with these requirements at December 31, 2022. Related to our third party administration business and in certain of our brokerage operations, we are responsible for client claim funds that we hold in a fiduciary capacity. We do not earn any interest income on the funds held. These client funds have been included in restricted cash, along with a corresponding liability in premiums payable to underwriting enterprises in the accompanying consolidated balance sheet.
Premiums and Fees Receivable	Premiums and Fees Receivable Premiums and fees receivable in the accompanying consolidated balance sheet are net of allowances for estimated policy cancellations and doubtful accounts. The allowance for estimated policy cancellations was $ 9.3 million and $ 10.0 million at December 31, 2022 and 2021, respectively, which represents a reserve for future reversals in commission and fee revenues related to the potential cancellation of client insurance policies that were in force as of each year end. The allowance for doubtful accounts was $ 11.1 million and $ 8.3 million at December 31, 2022 and 2021, respectively. We establish the allowance for estimated policy cancellations through a charge to revenues and the allowance for doubtful accounts through a charge to operating expenses. Both of these allowances are based on estimates and assumptions using historical data to project future experience. Such estimates and assumptions could change in the future as more information becomes known which could impact the amounts reported and disclosed herein. We periodically review the adequacy of these allowances and make adjustments as necessary.
Derivative Instruments	Derivative Instruments We are exposed to market risks, including changes in foreign currency exchange rates and interest rates. To manage the risk related to these exposures, we enter into various derivative instruments that reduce these risks by creating offsetting exposures. In the normal course of business, we are exposed to the impact of foreign currency fluctuations that impact our results of operations and cash flows. We utilize a foreign currency risk management program involving foreign currency derivatives that consist of several monthly put/call options designed to hedge a portion of our future foreign currency disbursements through various future payment dates. To mitigate the counterparty credit risk we only enter into contracts with major financial institutions based upon their credit ratings and other factors. These derivative instrument contracts are cash flow hedges that qualify for hedge accounting and primarily hedge against fluctuations between changes in the British pound and Indian Rupee versus the U.S. dollar. Changes in fair value of the derivative instruments are reflected in other comprehensive earnings in the accompanying consolidated balance sheet. The impact of the hedge at maturity is recognized in the income statement as a component of investment income, compensation and operating expenses depending on the nature of the hedged item. We enter into various long-term debt agreements. We use interest rate derivatives, typically swaps, to reduce our exposure to the effects of interest rate fluctuations on the forecasted interest rates for up to three years into the future. These derivative instrument contracts are periodically monitored for hedge ineffectiveness, the amount of which has not been material to the accompanying consolidated financial statements. We do not use derivatives for trading or speculative purposes.
Premium Financing	Premium Financing Seven subsidiaries of the brokerage segment make short-term loans (generally with terms of twelve months or less) to our clients to finance premiums. These premium financing contracts are structured to minimize potential bad debt expense to us. Such receivables are generally considered delinquent after seven days of the payment due date. In normal course, insurance policies are canceled within one month of the contractual payment due date if the payment remains delinquent. We recognize interest income as it is earned over the life of the contract using the “level-yield” method. Unearned interest related to contracts receivable is included in the receivable balance in the accompanying consolidated balance sheet. The outstanding loan receivable balance was $ 546.3 million and $ 509.7 million at December 31, 2022 and 2021, respectively.
Fixed Assets	Fixed Assets We carry fixed assets at cost, less accumulated depreciation, in the accompanying consolidated balance sheet. We periodically review long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying value of the assets may not be recoverable. Under those circumstances, if the fair value were less than the carrying amount of the asset, we would recognize a loss for the difference. Depreciation for fixed assets is computed using the straight-line method over the following estimated useful lives: Useful Life Office equipment Three to ten years Furniture and fixtures Three to ten years Computer equipment Three to five years Building Fifteen to forty years Software Three to five years Refined fuel plants Ten years Leasehold improvements Shorter of the lease term or useful life of the asset
Intangible Assets	Intangible Assets Intangible assets represent the excess of cost over the estimated fair value of net tangible assets of acquired businesses. Our primary intangible assets are classified as either goodwill, expiration lists, non-compete agreements or trade names. Expiration lists, non‑compete agreements and trade names are amortized using the straight-line method over their estimated useful lives ( two to fifteen years for expiration lists, two to six years for non-compete agreements and two to fifteen years for trade names), while goodwill is not subject to amortization. The establishment of goodwill, expiration lists, non-compete agreements and trade names and the determination of estimated useful lives are primarily based on valuations we receive from qualified independent appraisers. The calculations of these amounts are based on estimates and assumptions using historical and projected financial information and recognized valuation methods. Different estimates or assumptions could produce different results. We carry identifiable intangible assets at cost, less accumulated amortization, in the accompanying consolidated balance sheet. We review all of our intangible assets for impairment periodically (at least annually for goodwill) and whenever events or changes in business circumstances indicate that the carrying value of the assets may not be recoverable. We perform such impairment reviews at the division (i.e., reporting unit) level with respect to goodwill and at the business unit level for amortizable intangible assets. While goodwill is not amortizable, it is tested for impairment at least annually in the fourth quarter, and more frequently if there are indicators of impairment or whenever business circumstances suggest that the carrying value of goodwill may not be recoverable. We may initially perform a qualitative analysis to determine if it is more likely than not that the goodwill balance is impaired. If a qualitative assessment is not performed or if a determination is made that it is not more likely than not that the fair value of the reporting unit exceeds its carrying amount, then we will perform a quantitative analysis. The fair value of each reporting unit is compared to its carrying value. If the fair value of the reporting unit is less than its carrying value, a non-cash impairment charge is recognized for the amount by which the carrying value exceeds the reporting unit’s fair value with the loss not exceeding the total amount of goodwill allocated to that reporting unit. We completed our 2022 annual assessment in the fourth quarter and concluded goodwill was not impaired, as the fair value of each reporting unit exceeded its carrying value. The carrying value of amortizable intangible assets attributable to each business or asset group is periodically reviewed by management to determine if there are events or changes in circumstances that would indicate that its carrying amount may not be recoverable. Accordingly, if there are any such changes in circumstances during the year, we assess the carrying value of the amortizable intangible assets by considering the estimated future undiscounted cash flows generated by the corresponding business or asset group. Any impairment identified through this assessment may require that the carrying value of related amortizable intangible assets be adjusted and charged against current period earnings as a component of amortization expense. Based on the results of impairment reviews in 2022, 2021 and 2020, we wrote off $ 2.0 million, $ 17.6 million and $ 51.7 million, respectively, of amortizable intangible assets primarily related to acquisitions (made prior to 2020) of our brokerage and risk management segments, which is included in amortization expense in the accompanying consolidated statement of earnings. The determinations of impairment indicators and fair value are based on estimates and assumptions related to the amount and timing of future cash flows and future interest rates. Such estimates and assumptions could change in the future as more information becomes known which could impact the amounts reported and disclosed herein.
Income Taxes	Income Taxes Our tax rate reflects the statutory tax rates applicable to our taxable earnings and tax planning in the various jurisdictions in which we operate. Significant judgment is required in determining the annual effective tax rate and in evaluating uncertain tax positions. We report a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in our tax return. We evaluate our tax positions using a two-step process. The first step involves recognition. We determine whether it is more likely than not that a tax position will be sustained upon tax examination based solely on the technical merits of the position. The technical merits of a tax position are derived from both statutory and judicial authority (legislation and statutes, legislative intent, regulations, rulings and case law) and their applicability to the facts and circumstances of the position. If a tax position does not meet the “more likely than not” recognition threshold, we do not recognize the benefit of that position in the financial statements. The second step is measurement. A tax position that meets the “more likely than not” recognition threshold is measured to determine the amount of benefit to recognize in the financial statements. The tax position is measured as the largest amount of benefit that has a likelihood of greater than 50% of being realized upon ultimate resolution with a taxing authority. Uncertain tax positions are measured based upon the facts and circumstances that exist at each reporting period and involve significant management judgment. Subsequent changes in judgment based upon new information may lead to changes in recognition, derecognition and measurement. Adjustments may result, for example, upon resolution of an issue with the taxing authorities, or expiration of a statute of limitations barring an assessment for an issue. We recognize interest and penalties, if any, related to unrecognized tax benefits in our provision for income taxes. Tax law requires certain items to be included in our tax returns at different times than such items are reflected in the financial statements. As a result, the annual tax expense reflected in our consolidated statements of earnings is different than that reported in our tax returns. Some of these differences are permanent, such as expenses that are not deductible in our tax returns, and some differences are temporary and reverse over time, such as depreciation expense and amortization expense deductible for income tax purposes. Temporary differences create deferred tax assets and liabilities. Deferred tax liabilities generally represent tax expense recognized in the financial statements for which a tax payment has been deferred, or expense which has been deducted in the tax return but has not yet been recognized in the financial statements. Deferred tax assets generally represent items that can be used as a tax deduction or credit in tax returns in future years for which a benefit has already been recorded in the financial statements. We establish or adjust valuation allowances for deferred tax assets when we estimate that it is more likely than not that future taxable income will be insufficient to fully use a deduction or credit in a specific jurisdiction. In assessing the need for the recognition of a valuation allowance for deferred tax assets, we consider whether it is more likely than not that some portion, or all, of the deferred tax assets will not be realized and adjust the valuation allowance accordingly. We evaluate all significant available positive and negative evidence as part of our analysis. Negative evidence includes the existence of losses in recent years. Positive evidence includes the forecast of future taxable income by jurisdiction, tax-planning strategies that would result in the realization of deferred tax assets and the presence of taxable income in prior carryback years. The underlying assumptions we use in forecasting future taxable income require significant judgment and take into account our recent performance. Such estimates and assumptions could change in the future as more information becomes known which could impact the amounts reported and disclosed herein. The ultimate realization of deferred tax assets depends on the generation of future taxable income during the periods in which temporary differences are deductible or creditable.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value accounting establishes a framework for measuring fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e., an exit price). This framework includes a fair value hierarchy that prioritizes the inputs to the valuation technique used to measure fair value. The classification of a financial instrument within the valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability on the measurement date. The three levels of the hierarchy in order of priority of inputs to the valuation technique are defined as follows: • Level 1 - Valuations are based on unadjusted quoted prices in active markets for identical financial instruments; • Level 2 - Valuations are based on quoted market prices, other than quoted prices included in Level 1, in markets that are not active or on inputs that are observable either directly or indirectly for the full term of the financial instrument; and • Level 3 - Valuations are based on pricing or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement of the financial instrument. Such inputs may reflect management’s own assumptions about the assumptions a market participant would use in pricing the financial instrument. The level in the fair value hierarchy within which the fair value measurement is classified is determined based on the lowest level input that is significant to the fair value measure in its entirety. The carrying amounts of financial assets and liabilities reported in the accompanying consolidated balance sheet for cash and cash equivalents, restricted cash, premiums and fees receivable, other current assets, premiums payable to underwriting enterprises, accrued compensation and other accrued liabilities and deferred revenue - current, at December 31, 2022 and 2021, approximate fair value because of the short-term duration of these instruments. See Note 3 to these consolidated financial statements for the fair values related to the establishment of intangible assets and the establishment and adjustment of earnout payables. See Note 8 to these consolidated financial statements for the fair values related to borrowings outstanding at December 31, 2022 and 2021 under our debt agreements. See Note 13 to these consolidated financial statements for the fair values related to investments at December 31, 2022 and 2021 under our defined benefit pension plan.
Litigation	Litigation We are the defendant in various legal actions related to claims, lawsuits and proceedings incident to the nature of our business. We record liabilities for loss contingencies, including legal costs (such as fees and expenses of external lawyers and other service providers) to be incurred, when it is probable that a liability has been incurred on or before the balance sheet date and the amount of the liability can be reasonably estimated. We do not discount such contingent liabilities. To the extent recovery of such losses and legal costs is probable under our insurance programs, we record estimated recoveries concurrently with the losses recognized. Significant management judgment is required to estimate the amounts of such contingent liabilities and the related insurance recoveries. In order to assess our potential liability, we analyze our litigation exposure based on available information, including consultation with outside counsel handling the defense of these matters. As these liabilities are uncertain by their nature, the recorded amounts may change due to a variety of different factors, including new developments in, or changes in approach, such as changing the settlement strategy as applicable to each matter.
Retention Bonus Arrangements	Retention Bonus Arrangements In connection with the hiring and retention of both new talent and experienced personnel, including our senior management, brokers and other key personnel, we have entered into various agreements with key employees setting up the conditions for the cash payment of certain retention bonuses. These bonuses are an incentive for these employees to remain with the company, for a fixed period of time, to allow us to capitalize on their knowledge and experience. We have various forms of retention bonus arrangements; some are paid up front and some are paid at the end of the term, but all are contingent upon successfully completing a minimum period of employment. A retention bonus that is paid to an employee upfront that is contingent on a certain minimum period of employment, will be initially classified as a prepaid asset and amortized to compensation expense as the future services are rendered over the duration of the stay period. A retention bonus that is paid to an employee at the end of the term that is contingent on a certain minimum period of employment, will be accrued as a liability through compensation expense as the future services are rendered over the duration of the stay period. If an employee leaves prior to the required time frame to earn the retention bonus outright, then all or any portion that is ultimately unearned or refundable, and recovered by the company if prepaid, is forfeited and reversed through compensation expense.
Stock-Based Compensation	Stock-Based Compensation We have several employee equity-settled and cash-settled share-based compensation plans. Equity-settled share-based payments to employees include grants of stock options, performance stock units and restricted stock units and are measured based on estimated grant date fair value. We have elected to use the Black-Scholes option pricing model to determine the fair value of stock options on the dates of grant. Performance stock units are measured on the probable outcome of the performance conditions applicable to each grant. Restricted stock units are measured based on the fair market values of the underlying stock on the dates of grant. Shares are issued on the vesting dates net of the minimum statutory tax withholding requirements, as applicable, to be paid by us on behalf of our employees. As a result, the actual number of shares issued will be fewer than the actual number of performance stock units and restricted stock units outstanding. Furthermore, we record the liability for withholding amounts to be paid by us as a reduction to additional paid-in capital when paid. Cash-settled share-based payments to employees include awards under our Performance Unit Program and stock appreciation rights. The fair value of the amount payable to employees in respect of cash-settled share-based payments is recognized as compensation expense, with a corresponding increase in liabilities, over the vesting period. The liability is remeasured at each reporting date and at settlement date. Any changes in fair value of the liability are recognized as compensation expense. We recognize share-based compensation expense over the requisite service period for awards expected to ultimately vest. Forfeitures are estimated on the date of grant and revised if actual or expected forfeiture activity differs from original estimates.
Employee Stock Purchase Plan	Employee Stock Purchase Plan We have an employee stock purchase plan (which we refer to as the ESPP), under which the sale of 8.0 million shares of our common stock has been authorized. Eligible employees may contribute up to 15 % of their compensation towards the quarterly purchase of our common stock at a purchase price equal to 95 % of the lesser of the fair market value of our common stock on the first business day or the last business day of the quarterly offering period. Eligible employees may annually purchase shares of our common stock with an aggregate fair market value of up to $ 25,000 (measured as of the first day of each quarterly offering period of each calendar year), provided that no employee may purchase more than 2,000 shares of our common stock under the ESPP during any calendar year. At December 31, 2022 , 5.3 million shares of our common stock was reserved for future issuance under the ESPP.
Defined Benefit Pension Plans	Defined Benefit Pension Plans We recognize in our consolidated balance sheet, an asset for our defined benefit pension plans’ overfunded status or a liability for our plans’ underfunded status. We recognize changes in the funded status of our defined benefit pension plans in comprehensive earnings in the year in which the changes occur. We use December 31 as the measurement date for our plans’ assets and benefit obligations. See Note 13 to these consolidated financial statements for additional information required to be disclosed related to our defined benefit pension plans.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
Summary of Significant Accounting Policies (Tables)	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Estimated Useful Life of Fixed Assets	Depreciation for fixed assets is computed using the straight-line method over the following estimated useful lives: Useful Life Office equipment Three to ten years Furniture and fixtures Three to ten years Computer equipment Three to five years Building Fifteen to forty years Software Three to five years Refined fuel plants Ten years Leasehold improvements Shorter of the lease term or useful life of the asset

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
Business Combinations (Tables)	Dec. 31, 2022
Business Combinations [Abstract]
Acquisition Method for Recording Business Combinations	During 2022, we acquired substantially all of the net assets of the following firms in exchange for our common stock and/or cash. These acquisitions have been accounted for using the acquisition method for recording business combinations (in millions, except share data): Name and Effective Date of Acquisition Common Common Cash Accrued Escrow Recorded Total Maximum (000s) Devitt Insurance Services Ltd — $ — $ 73.6 $ 1.3 $ 3.4 $ 12.6 $ 90.9 $ 12.5 Innovu Group Holding — — 85.4 — — — 85.4 — f3 Companies 352 61.7 33.1 — 5.0 6.1 105.9 25.0 M&T Insurance Agency — — 171.0 — — — 171.0 — PlUS Limited LLC 74 10.6 35.6 — 3.8 116.4 166.4 150.0 Thirty-two other acquisitions 300 50.6 457.2 41.7 27.0 106.9 683.4 230.2 726 $ 122.9 $ 855.9 $ 43.0 $ 39.2 $ 242.0 $ 1,303.0 $ 417.7
Summary of Estimated Fair Values of Net Assets Acquired	The following is a summary of the estimated fair values of the net assets acquired at the date of each acquisition made in 2022 (in millions): DIS IGH f3 M&T PIU Thirty-two Other Total Cash and restricted cash $ 3.9 $ 7.8 $ — $ 6.1 $ 2.8 $ 30.9 $ 51.5 Other current assets 18.5 6.5 0.1 27.6 — 73.9 126.6 Fixed assets 0.4 0.5 — 0.2 — 2.1 3.2 Noncurrent assets 1.3 2.0 1.8 1.4 — 11.0 17.5 Goodwill 60.4 47.2 40.5 87.0 116.4 358.4 709.9 Expiration lists 29.0 35.0 65.1 78.9 44.6 311.4 564.0 Non-compete agreements 0.7 4.0 0.2 0.9 1.0 12.7 19.5 Trade names 0.9 0.8 — — 4.0 0.4 6.1 Total assets acquired 115.1 103.8 107.7 202.1 168.8 800.8 1,498.3 Current liabilities 15.3 11.2 0.3 30.2 2.4 90.9 150.3 Noncurrent liabilities 8.9 7.2 1.5 0.9 — 26.5 45.0 Total liabilities assumed 24.2 18.4 1.8 31.1 2.4 117.4 195.3 Total net assets acquired $ 90.9 $ 85.4 $ 105.9 $ 171.0 $ 166.4 $ 683.4 $ 1,303.0
Summary of Unaudited Pro Forma Historical Results	The following is a summary of the unaudited pro forma historical results, as if these entities had been acquired at January 1, 2021 (in millions, except per share data): Year Ended December 31, 2022 2021 Total revenues $ 8,710.2 $ 8,445.8 Net earnings attributable to controlling interests 1,114.8 907.1 Basic net earnings per share 5.29 4.46 Diluted net earnings per share 5.18 4.36

Contracts with Customers (Table

Contracts with Customers (Tables)	12 Months Ended
Contracts with Customers (Tables)	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Summary of Unbilled Receivables, Contract Assets and Contract Liabilities from Contracts with Customers	Information about unbilled receivables, contract assets and contract liabilities from contracts with customers is as follows (in millions): December 31, 2022 December 31, 2021 Unbilled receivables $ 910.9 $ 730.0 Deferred contract costs 144.5 129.7 Deferred revenue 609.3 579.6
Summary of Changes in Deferred Revenue Balances	Significant changes in the deferred revenue balances, which include foreign currency translation adjustments, during the period are as follows (in millions): Brokerage Risk Total Deferred revenue at December 31, 2020 $ 354.7 $ 186.6 $ 541.3 Incremental deferred revenue 325.0 102.1 427.1 Revenue recognized during the year ended December 31, ( 296.1 ) ( 103.5 ) ( 399.6 ) Net change in collected billings/deposits received from customers ( 3.6 ) ( 0.7 ) ( 4.3 ) Impact of changes in foreign exchange rates ( 3.7 ) ( 0.8 ) ( 4.5 ) Deferred revenue recognized from business acquisitions 19.6 — 19.6 Deferred revenue at December 31, 2021 395.9 183.7 579.6 Incremental deferred revenue 342.3 103.2 445.5 Revenue recognized during the year ended December 31, ( 326.3 ) ( 104.6 ) ( 430.9 ) Net change in collected billings/deposits received from customers 21.4 ( 7.0 ) 14.4 Impact of changes in foreign exchange rates ( 17.9 ) — ( 17.9 ) Deferred revenue recognized from business acquisitions 18.6 — 18.6 Deferred revenue at December 31, 2022 $ 434.0 $ 175.3 $ 609.3
Summary of Expected Revenue Related to Performance Obligations	The estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied) at the end of the reporting period is as follows (in millions): Brokerage Risk Total 2023 $ 404.6 $ 48.4 $ 453.0 2024 26.3 64.5 90.8 2025 1.4 27.2 28.6 2026 0.8 14.4 15.2 2027 0.5 8.4 8.9 Thereafter 0.4 12.4 12.8 Total $ 434.0 $ 175.3 $ 609.3

Other Financial Data (Tables)

Other Financial Data (Tables)	12 Months Ended
Other Financial Data (Tables)	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Summary of Major Classes of Other Current Assets	Major classes of other current assets consist of the following (in millions): December 31, 2022 2021 Premium finance advances and loans $ 546.3 $ 509.7 Accrued supplemental, direct bill and other receivables 567.8 563.0 Refined coal production related receivables 5.7 76.9 Deferred contract costs 144.5 129.7 Prepaid expenses 197.2 171.7 Total other current assets $ 1,461.5 $ 1,451.0

Fixed Assets (Tables)

Fixed Assets (Tables)	12 Months Ended
Fixed Assets (Tables)	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Summary of Fixed Assets	Major classes of fixed assets consist of the following (in millions): December 31, 2022 2021 Office equipment $ 32.2 $ 36.2 Furniture and fixtures 142.0 137.1 Leasehold improvements 190.7 170.8 Computer equipment 295.8 247.1 Land and buildings - corporate headquarters 145.3 145.3 Software 583.4 532.2 Other 16.9 17.2 Work in process 56.0 23.0 1,462.3 1,308.9 Accumulated depreciation ( 886.1 ) ( 808.1 ) Net fixed assets $ 576.2 $ 500.8

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
Intangible Assets (Tables)	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Carrying Amount of Goodwill Allocated by Domestic and Foreign Operations	The carrying amount of goodwill at December 31, 2022 and 2021 allocated by domestic and foreign operations is as follows (in millions): Brokerage Risk Corporate Total At December 31, 2022 United States $ 5,065.7 $ 74.8 $ — $ 5,140.5 United Kingdom 2,180.2 17.7 — 2,197.9 Canada 569.7 — — 569.7 Australia 467.6 10.2 — 477.8 New Zealand 203.8 9.5 — 213.3 Other foreign 871.1 — 19.1 890.2 Total goodwill - net $ 9,358.1 $ 112.2 $ 19.1 $ 9,489.4 At December 31, 2021 United States $ 4,409.1 $ 64.8 $ — $ 4,473.9 United Kingdom 2,198.7 15.0 — 2,213.7 Canada 572.9 — — 572.9 Australia 487.2 10.9 — 498.1 New Zealand 217.6 10.2 — 227.8 Other foreign 659.1 — 20.7 679.8 Total goodwill - net $ 8,544.6 $ 100.9 $ 20.7 $ 8,666.2
Changes in Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for 2022 and 2021 are as follows (in millions): Brokerage Risk Corporate Total Balance as of December 31, 2020 $ 6,053.6 $ 70.5 $ 2.9 $ 6,127.0 Goodwill acquired during the year 2,511.8 31.6 18.1 2,561.5 Goodwill adjustments related to appraisals and other acquisition 50.8 — — 50.8 Goodwill written-off related to sales of business ( 1.0 ) — — ( 1.0 ) Foreign currency translation adjustments during the year ( 70.6 ) ( 1.2 ) ( 0.3 ) ( 72.1 ) Balance as of December 31, 2021 8,544.6 100.9 20.7 8,666.2 Goodwill acquired during the year 693.9 16.0 — 709.9 Goodwill adjustments related to appraisals and other acquisition 428.3 ( 1.6 ) 0.2 426.9 Foreign currency translation adjustments during the year ( 308.7 ) ( 3.1 ) ( 1.8 ) ( 313.6 ) Balance as of December 31, 2022 $ 9,358.1 $ 112.2 $ 19.1 $ 9,489.4
Major Classes of Amortizable Intangible Assets	Major classes of amortizable intangible assets consist of the following (in millions): December 31, 2022 2021 Expiration lists $ 6,472.3 $ 6,696.8 Accumulated amortization - expiration lists ( 3,178.5 ) ( 2,812.2 ) 3,293.8 3,884.6 Non-compete agreements 91.3 76.0 Accumulated amortization - non-compete agreements ( 67.5 ) ( 62.8 ) 23.8 13.2 Trade names 108.5 105.2 Accumulated amortization - trade names ( 54.0 ) ( 49.0 ) 54.5 56.2 Net amortizable assets $ 3,372.1 $ 3,954.0
Estimated Aggregate Amortization Expense	Estimated aggregate amortization expense for each of the next five years is as follows (in millions): 2023 $ 466.1 2024 429.5 2025 388.5 2026 349.7 2027 320.3 Thereafter 1,418.0 Total $ 3,372.1

Credit and Other Debt Agreeme_2

Credit and Other Debt Agreements (Tables)	12 Months Ended
Credit and Other Debt Agreements (Tables)	Dec. 31, 2022
Debt Disclosure [Abstract]
Summary of Corporate and Other Debt	The following is a summary of our corporate and other debt (in millions): December 31, 2022 2021 Senior Notes: Semi-annual payments of interest, fixed rate of 2.40 %, balloon due November 9, 2031 $ 400.0 $ 400.0 Semi-annual payments of interest, fixed rate of 3.50 %, balloon due May 20, 2051 850.0 850.0 Semi-annual payments of interest, fixed rate of 3.05 %, balloon due March 9, 2052 350.0 350.0 Total Senior Notes 1,600.0 1,600.0 Note Purchase Agreements: Semi-annual payments of interest, fixed rate of 3.69 %, balloon due June 14, 2022 — 200.0 Semi-annual payments of interest, fixed rate of 5.49 %, balloon due February 10, 2023 50.0 50.0 Semi-annual payments of interest, fixed rate of 4.13 %, balloon due June 24, 2023 200.0 200.0 Semi-annual payments of interest, fixed rate of 4.72 %, balloon due February 13, 2024 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.58 %, balloon due February 27, 2024 325.0 325.0 Quarterly payments of interest, floating rate of 90 day LIBOR plus 1.40 %, balloon due June 13, 2024 50.0 50.0 Semi-annual payments of interest, fixed rate of 4.31 %, balloon due June 24, 2025 200.0 200.0 Semi-annual payments of interest, fixed rate of 4.85 %, balloon due February 13, 2026 140.0 140.0 Semi-annual payments of interest, fixed rate of 4.73 %, balloon due February 27, 2026 175.0 175.0 Semi-annual payments of interest, fixed rate of 4.40 %, balloon due June 2, 2026 175.0 175.0 Semi-annual payments of interest, fixed rate of 4.36 %, balloon due June 24, 2026 150.0 150.0 Semi-annual payments of interest, fixed rate of 3.75 %, balloon due January 30, 2027 30.0 30.0 Semi-annual payments of interest, fixed rate of 4.09 %, balloon due June 27, 2027 125.0 125.0 Semi-annual payments of interest, fixed rate of 4.09 %, balloon due August 2, 2027 125.0 125.0 Semi-annual payments of interest, fixed rate of 4.14 %, balloon due August 4, 2027 98.0 98.0 Semi-annual payments of interest, fixed rate of 3.46 %, balloon due December 1, 2027 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.55 %, balloon due June 2, 2028 75.0 75.0 Semi-annual payments of interest, fixed rate of 4.34 %, balloon due June 13, 2028 125.0 125.0 Semi-annual payments of interest, fixed rate of 5.04 %, balloon due February 13, 2029 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.98 %, balloon due February 27, 2029 100.0 100.0 Semi-annual payments of interest, fixed rate of 4.19 %, balloon due June 27, 2029 50.0 50.0 Semi-annual payments of interest, fixed rate of 4.19 %, balloon due August 2, 2029 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.48 %, balloon due December 2, 2029 50.0 50.0 Semi-annual payments of interest, fixed rate of 3.99 %, balloon due January 30, 2030 341.0 341.0 Semi-annual payments of interest, fixed rate of 4.44 %, balloon due June 13, 2030 125.0 125.0 Semi-annual payments of interest, fixed rate of 5.14 %, balloon due March 13, 2031 180.0 180.0 Semi-annual payments of interest, fixed rate of 4.70 %, balloon due June 2, 2031 25.0 25.0 Semi-annual payments of interest, fixed rate of 4.09 %, balloon due January 30, 2032 69.0 69.0 Semi-annual payments of interest, fixed rate of 4.34 %, balloon due June 27, 2032 75.0 75.0 Semi-annual payments of interest, fixed rate of 4.34 %, balloon due August 2, 2032 75.0 75.0 Semi-annual payments of interest, fixed rate of 4.59 %, balloon due June 13, 2033 125.0 125.0 Semi-annual payments of interest, fixed rate of 5.29 %, balloon due March 13, 2034 40.0 40.0 Semi-annual payments of interest, fixed rate of 4.48 %, balloon due June 12, 2034 175.0 175.0 Semi-annual payments of interest, fixed rate of 4.24 %, balloon due January 30, 2035 79.0 79.0 Semi-annual payments of interest, fixed rate of 2.44 %, balloon due February 10, 2036 100.0 100.0 Semi-annual payments of interest, fixed rate of 2.46 %, balloon due May 5, 2036 75.0 75.0 Semi-annual payments of interest, fixed rate of 4.69 %, balloon due June 13, 2038 75.0 75.0 Semi-annual payments of interest, fixed rate of 5.45 %, balloon due March 13, 2039 40.0 40.0 Semi-annual payments of interest, fixed rate of 4.49 %, balloon due January 30, 2040 56.0 56.0 Total Note Purchase Agreements 4,248.0 4,448.0 Credit Agreement: Periodic payments of interest and principal, prime or SOFR plus up to 1.40 %, expires June 7, 2024 60.0 45.0 Premium Financing Debt Facility - expires September 15, 2024 : Facility B AUD denominated tranche, interbank rates plus 1.500 % 217.6 209.5 NZD denominated tranche, interbank rates plus 1.850 % — 6.8 Facility C and D AUD denominated tranche, interbank rates plus 0.830 % 15.2 2.1 NZD denominated tranche, interbank rates plus 0.990 % 9.1 10.0 Total Premium Financing Debt Facility 241.9 228.4 Total corporate and other debt 6,149.9 6,321.4 Less unamortized debt acquisition costs on Senior Notes and Note Purchase Agreements ( 20.6 ) ( 22.6 ) Less unamortized discount on Bonds Payable ( 14.6 ) ( 15.2 ) Net corporate and other debt $ 6,114.7 $ 6,283.6 The Senior Notes in the table above are registered by the company with the Securities and Exchange Commission and are not guaranteed.

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
Earnings per Share (Tables)	Dec. 31, 2022
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net EPS	The following table sets forth the computation of basic and diluted net earnings per share (in millions, except per share data): Year Ended December 31, 2022 2021 2020 Net earnings attributable to controlling interests $ 1,114.2 $ 906.8 $ 818.8 Weighted average number of common shares outstanding 210.3 202.7 191.0 Dilutive effect of stock options using the treasury stock 4.4 4.6 4.0 Weighted average number of common and common 214.7 207.3 195.0 Basic net earnings per share $ 5.30 $ 4.47 $ 4.29 Diluted net earnings per share $ 5.19 $ 4.37 $ 4.20

Stock Option Plans (Tables)

Stock Option Plans (Tables)	12 Months Ended
Stock Option Plans (Tables)	Dec. 31, 2022
Text Block [Abstract]
Black-Scholes Option Pricing Model with Weighted Average	For purposes of expense recognition in 2022, 2021 and 2020, the estimated fair values of the stock option grants are amortized to expense over the options’ vesting period. We estimated the fair value of stock options at the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: Year Ended December 31, 2022 2021 2020 Expected dividend yield 1.3 % 1.5 % 2.1 % Expected risk-free interest rate 1.9 % 0.9 % 0.7 % Volatility 23.1 % 22.9 % 17.3 % Expected life (in years) 5.4 5.4 5.4
Stock Option Activity and Related Information	The following is a summary of our stock option activity and related information for 2022 and 2021 (in millions, except exercise price and year data): Weighted Average Weighted Remaining Shares Average Contractual Aggregate Under Exercise Term Intrinsic Option Price (in years) Value Year Ended December 31, 2022 Beginning balance 7.5 $ 81.30 Granted 2.4 157.74 Exercised ( 1.4 ) 53.53 Forfeited or canceled ( 0.2 ) 109.10 Ending balance 8.3 $ 107.47 4.18 $ 668.9 Exercisable at end of year 1.8 $ 61.11 1.56 $ 230.8 Ending unvested and expected to vest 5.9 $ 118.80 4.86 $ 413.2 Year Ended December 31, 2021 Beginning balance 7.5 $ 65.09 Granted 1.6 127.90 Exercised ( 1.4 ) 49.10 Forfeited or canceled ( 0.2 ) 88.84 Ending balance 7.5 $ 81.30 3.90 $ 666.3 Exercisable at end of year 2.1 $ 51.46 1.57 $ 242.3 Ending unvested and expected to vest 5.1 $ 91.56 4.72 $ 401.7
Other Information Regarding Stock Options Outstanding and Exercisable	Other information regarding stock options outstanding and exercisable at December 31, 2022 is summarized as follows (in millions, except exercise price and year data): Options Outstanding Options Exercisable Weighted Average Remaining Weighted Weighted Contractual Average Average Number Term Exercise Number Exercise Range of Exercise Prices Outstanding (in years) Price Exercisable Price $ 43.71 $ — $ 43.71 $ 0.4 $ 0.21 $ 43.71 $ 0.4 $ 43.71 49.55 — 56.86 0.7 1.21 56.84 0.7 56.85 70.74 — 70.74 0.8 2.21 70.74 0.4 70.74 79.59 — 79.59 1.0 3.20 79.59 0.3 79.59 86.17 — 86.17 1.5 4.20 86.17 — 86.17 127.90 — 127.90 1.5 5.21 127.90 — — 156.85 — 156.85 1.2 6.09 156.85 — — 158.56 — 161.14 1.2 6.21 158.65 — — $ 43.71 $ — $ 161.14 $ 8.3 $ 4.18 $ 107.47 $ 1.8 $ 61.11

Restricted Stock, Performance_2

Restricted Stock, Performance Share and Cash Awards (Tables)	12 Months Ended
	Dec. 31, 2022
Text Block [Abstract]
Schedule of Restricted Stock Awards Vesting Periods	The vesting periods of the 2022, 2021 and 2020 restricted stock unit awards are as follows (in actual shares): Restricted Stock Units Granted Vesting Period 2022 2021 2020 One year 9,270 10,105 16,740 Two years — 2,105 8,870 Five years 641,085 314,374 397,000 Total shares granted 650,355 326,584 422,610

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
Retirement Plans (Tables)	Dec. 31, 2022
Retirement Benefits [Abstract]
Reconciliation of Balances of Pension Benefit Obligation and Fair Value of Plan Assets	A reconciliation of the beginning and ending balances of the pension benefit obligation and fair value of plan assets and the funded status of the plan is as follows (in millions): Year Ended December 31, 2022 2021 Change in pension benefit obligation: Benefit obligation at beginning of year $ 279.4 $ 290.6 Service cost 0.5 0.5 Interest cost 6.8 6.4 Net actuarial gain ( 58.7 ) ( 2.8 ) Benefits paid ( 16.1 ) ( 15.3 ) Benefit obligation at end of year $ 211.9 $ 279.4 Change in plan assets: Fair value of plan assets at beginning of year $ 282.3 $ 262.8 Actual (loss) return on plan assets ( 53.7 ) 34.8 Contributions by the company — — Benefits paid ( 16.1 ) ( 15.3 ) Fair value of plan assets at end of year $ 212.5 $ 282.3 Funded status of the plan (underfunded) $ 0.6 $ 2.9 Amounts recognized in the consolidated balance sheet Noncurrent assets - accrued benefit liability $ 0.6 $ 2.9 Accumulated other comprehensive income 54.2 42.5 Net amount included in retained earnings $ 54.8 $ 45.4
Components of Net Periodic Pension Benefit Cost and Other Changes in Plan Assets and Obligations Recognized in Earnings and Other Comprehensive Earnings	The components of the net periodic pension benefit cost for the plan and other changes in plan assets and obligations recognized in earnings and other comprehensive earnings consist of the following (in millions): Year Ended December 31, 2022 2021 2020 Net periodic pension cost: Service cost $ 0.5 $ 0.5 $ 0.8 Interest cost on benefit obligation 6.8 6.4 8.0 Expected return on plan assets ( 19.1 ) ( 17.7 ) ( 16.4 ) Amortization of net loss 2.4 5.9 6.2 Net periodic benefit income ( 9.4 ) ( 4.9 ) ( 1.4 ) Other changes in plan assets and obligations recognized Net loss (gain) incurred 14.1 ( 19.9 ) 4.7 Amortization of net loss ( 2.4 ) ( 5.9 ) ( 6.2 ) Total recognized in other comprehensive income (loss) 11.7 ( 25.8 ) ( 1.5 ) Total recognized in net periodic pension cost and other $ 2.3 $ ( 30.7 ) $ ( 2.9 )
Weighted Average Assumptions of Pension Benefit Obligation and Net Periodic Pension Benefit Cost	The following weighted average assumptions were used at December 31 in determining the plan’s pension benefit obligation: December 31, 2022 2021 Discount rate 5.25 % 2.50 % Weighted average expected long-term rate of return on plan assets 7.00 % 7.00 % The following weighted average assumptions were used at January 1 in determining the plan’s net periodic pension benefit cost: Year Ended December 31, 2022 2021 2020 Discount rate 2.50 % 2.25 % 3.00 % Weighted average expected long-term rate of return on plan assets 7.00 % 7.00 % 7.00 %
Schedule of Benefit Payments Expected to be Paid by Plan	The following benefit payments are expected to be paid by the plan (in millions): 2023 $ 17.1 2024 17.1 2025 17.3 2026 17.3 2027 17.3 2028 to 2032 81.9
Summary of Plans Weighted Average Asset Allocations	The following is a summary of the plan’s weighted average asset at December 31 by asset category: December 31, Asset Category 2022 2021 Equity securities 62.0 % 60.0 % Debt securities 31.0 % 32.0 % Real estate 7.0 % 8.0 % Total 100.0 % 100.0 %
Summary of Plan's Assets Carried at Fair Value	The following is a summary of the plan’s assets carried at fair value as of December 31 by level within the fair value hierarchy (in millions): December 31, Fair Value Hierarchy 2022 2021 Level 1 $ — $ — Level 2 112.9 158.1 Level 3 99.6 124.2 Total fair value $ 212.5 $ 282.3
Reconciliation of Beginning and Ending Balances for Level 3 Assets of Plan Measured at Fair Value	The following is a reconciliation of the beginning and ending balances for the Level 3 assets of the plan measured at fair value (in millions): Year Ended December 31, 2022 2021 Fair value at January 1 $ 124.2 $ 121.0 Settlements ( 1.5 ) ( 15.2 ) Unrealized (loss) gain ( 23.1 ) 18.4 Fair value at December 31 $ 99.6 $ 124.2

Leases (Tables)

Leases (Tables)	12 Months Ended
Leases (Tables)	Dec. 31, 2022
Leases [Abstract]
Components of Lease Expense	The components of lease expense are as follows (in millions): Statement of Earnings Year ended Lease Components Classification December 31, 2022 Operating lease expense Operating expense $ 139.9 Variable lease expense Operating expense 21.7 Sublease income Investment income ( 1.2 ) Total net lease expense $ 160.4
Summary of Supplemental Cash Flow Information Related to Leases	Year ended Supplemental Cash Flow Information Related to Leases (in millions) December 31, 2022 Cash paid for amounts included in the measurement of Operating cash flows from operating leases $ 121.4 Right-of-use assets obtained in exchange for new $ 102.9
Summary of Supplemental Balance Sheet Information Related to Leases	Supplemental balance sheet information related to leases is as follows (in millions, except lease term and discount rate): Lease Components Balance Sheet Classification December 31, 2022 Lease right-of-use assets Right-of-use assets $ 346.7 Other current lease liabilities Accrued compensation and other current liabilities 82.4 Lease liabilities Lease liabilities - noncurrent 300.4 Total lease liabilities $ 382.8 Weighted-average remaining lease term, years 5.4 Weighted-average discount rate 3.3 %
Maturities of Operating Lease Liabilities	Maturities of operating lease liabilities for each of the next five years and thereafter are as follows (in millions): 2023 $ 98.6 2024 84.2 2025 67.7 2026 54.3 2027 41.7 Thereafter 72.6 Total lease payments 419.1 Less interest ( 36.3 ) Total $ 382.8

Derivatives and Hedging Activ_2

Derivatives and Hedging Activity (Tables)	12 Months Ended
Derivatives and Hedging Activity (Tables)	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Notional and Fair Values of Derivative Instruments	The notional and fair values of derivatives designated as hedging instruments are as follows at December 31, 2022 and 2021 (in millions): Derivative Assets Derivative Liabilities Notional Balance Sheet Fair Balance Sheet Fair Instrument Amount Classification Value Classification Value At December 31, 2022 Interest rate contracts $ 950.0 Other current assets $ 56.5 Accrued compensation and $ — Other noncurrent assets 56.6 other current liabilities Other noncurrent liabilities — Foreign exchange contracts (1) 113.0 Other current assets 0.8 Accrued compensation and 18.5 14.5 other current liabilities Other noncurrent assets — Other noncurrent liabilities 27.0 Total $ 1,063.0 $ 128.4 $ 45.5 At December 31, 2021 Interest rate contracts $ 1,000.0 Other current assets $ 4.8 Accrued compensation and $ 1.3 Other noncurrent assets 3.4 other current liabilities Other noncurrent liabilities 11.5 Foreign exchange contracts (1) 17.3 Other current assets 4.3 Accrued compensation and 1.3 other current liabilities Other noncurrent assets 4.3 Other noncurrent liabilities 7.2 Total $ 1,017.3 $ 16.8 $ 21.3 (1) Included within foreign exchange contracts at December 31, 2022 were $ 948.8 million of call options offset with $ 948.8 million of put options, and $ 12.4 million of buy forwards offset with $ 125.4 million of sell forwards. Included within foreign exchange contracts at December 31, 2021 were $ 483.8 million of call options offset with $ 483.8 million of put options, and $ 10.5 million of buy forwards offset with $ 27.9 million of sell forwards.
Summary of Amounts of Derivative Gains (Losses) Recognized In Accumulated Other Comprehensive Loss	The effect of cash flow hedge accounting on accumulated other comprehensive loss were as follows (in millions): Instrument Amount of Amount of Amount of Statement of Earnings Year ended December 31, 2022 Interest rate contracts $ 179.3 $ ( 1.2 ) $ — Interest expense Foreign exchange contracts ( 26.8 ) 6.3 ( 0.1 ) Commission revenue ( 1.1 ) 1.9 Compensation expense ( 0.8 ) 1.4 Operating expense Total $ 152.5 $ 3.2 $ 3.2 Year ended December 31, 2021 Interest rate contracts $ 35.8 $ ( 1.1 ) $ — Interest expense Foreign exchange contracts ( 13.5 ) ( 3.3 ) — Commission revenue ( 0.8 ) 1.0 Compensation expense ( 0.6 ) 0.7 Operating expense Total $ 22.3 $ ( 5.8 ) $ 1.7 (1) During 2022, the amount excluded from the assessment of hedge effectiveness for our foreign exchange contracts recognized in accumulated other comprehensive loss was a gain of $ 0.9 million.

Commitments, Contingencies an_2

Commitments, Contingencies and Off-Balance Sheet Arrangements (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligations	Our future minimum cash payments, including interest, associated with our contractual obligations pursuant to the Senior Notes, Note purchase agreements, Credit Agreement, Premium Financing Debt Facility, operating leases and purchase commitments at December 31, 2022 were as follows (in millions): Payments Due by Period Contractual Obligations 2023 2024 2025 2026 2027 Thereafter Total Senior Notes $ — $ — $ — $ — $ — $ 1,600.0 $ 1,600.0 Note purchase agreements 250.0 475.0 200.0 640.0 478.0 2,205.0 4,248.0 Credit Agreement 60.0 — — — — — 60.0 Premium Financing Debt Facility 241.9 — — — — — 241.9 Interest on debt 229.0 212.3 197.7 178.8 160.4 1,408.1 2,386.3 Total debt obligations 780.9 687.3 397.7 818.8 638.4 5,213.1 8,536.2 Operating lease obligations 98.6 84.2 67.7 54.3 41.7 72.6 419.1 Less sublease arrangements ( 0.9 ) ( 0.6 ) ( 0.3 ) ( 0.3 ) ( 0.2 ) — ( 2.3 ) Outstanding purchase obligations 117.4 86.8 36.1 16.8 12.3 14.6 284.0 Total contractual obligations $ 996.0 $ 857.7 $ 501.2 $ 889.6 $ 692.2 $ 5,300.3 $ 9,237.0
Off-Balance Sheet Commitments	Off-Balance Sheet Commitments - Our total unrecorded commitments associated with outstanding letters of credit, financial guarantees and funding commitments at December 31, 2022 were as follows (in millions): Total Amount of Commitment Expiration by Period Amounts Off-Balance Sheet Commitments 2023 2024 2025 2026 2027 Thereafter Committed Letters of credit $ — $ — $ — $ — $ — $ 13.0 $ 13.0 Financial guarantees 1.4 2.0 0.2 0.1 0.1 — 3.8 Total commitments $ 1.4 $ 2.0 $ 0.2 $ 0.1 $ 0.1 $ 13.0 $ 16.8
Outstanding Letters of Credit and Funding Commitments	Our commitments associated with outstanding letters of credit, financial guarantees and funding commitments at December 31, 2022 were as follows (all dollar amounts in table are in millions): Description, Purpose and Trigger Collateral Compensation Maximum Liability Other investments Funding commitment to an equity investment - None None $ — $ — Trigger - Agreed conditions met Other Credit support under letters of credit (LOC) for None None 9.2 17.4 Trigger - We do not reimburse the insurance Credit enhancement under letters of credit for our None Reimbursement of LOC fees 2.5 — Trigger - Dissolution or catastrophic financial Collateral related to claims funds held in a fiduciary None None 0.8 — Trigger - Claim payments are not made Credit support under letters of credit in lieu of security None None 0.5 — Trigger - Lease payments do not get made Financial guarantees of loans to 5 Canadian-based (1) None 0.8 — Trigger - Default on loan payments Financial guarantee of external loan to subsidiary in None None 3.0 — Trigger - Default on loan payments $ 16.8 $ 17.4 (1) The guarantees are collateralized by shares in minority holdings of our Canadian operating companies.

Insurance Operations (Tables)

Insurance Operations (Tables)	12 Months Ended
Insurance Operations (Tables)	Dec. 31, 2022
Insurance [Abstract]
Summary of Reconciliations of Direct to Net premiums on Written and Earned Basis Related to Wholly Owned Underwriting Enterprise Subsidiary	Reconciliations of direct to net premiums, on a written and earned basis, for 2022, 2021 and 2020 related to the wholly-owned underwriting enterprise subsidiary discussed above are as follows (in millions): 2022 2021 2020 Written Earned Written Earned Written Earned Direct $ 24.4 $ 28.7 $ 30.9 $ 35.9 $ 37.7 $ 40.7 Assumed 0.4 0.2 0.2 0.2 0.1 0.9 Ceded ( 24.8 ) ( 28.9 ) ( 31.1 ) ( 36.1 ) ( 37.8 ) ( 41.6 ) Net $ — $ — $ — $ — $ — $ —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Components of Earnings Before Income Taxes and Provision for Income Taxes	Significant components of earnings before income taxes and the provision for income taxes are as follows (in millions): Year Ended December 31, 2022 2021 2020 Earnings before income taxes: United States $ 781.6 $ 593.0 $ 524.4 Foreign, principally Australia, Canada, New Zealand 545.4 382.1 346.5 Total earnings before income taxes $ 1,327.0 $ 975.1 $ 870.9 Provision for income taxes: Federal: Current $ 109.1 $ 44.6 $ 43.6 Deferred ( 3.5 ) ( 151.6 ) ( 112.4 ) 105.6 ( 107.0 ) ( 68.8 ) State and local: Current 114.3 50.6 36.6 Deferred ( 83.5 ) ( 11.6 ) ( 19.3 ) 30.8 39.0 17.3 Foreign: Current 196.6 108.8 94.6 Deferred ( 122.0 ) ( 20.7 ) ( 30.3 ) 74.6 88.1 64.3 Total provision for income taxes $ 211.0 $ 20.1 $ 12.8
Reconciliation of Provision for Income Taxes with Federal Statutory Income Tax Rate	A reconciliation of the provision for income taxes with the U.S. federal statutory income tax rate is as follows (in millions, except percentages): Year Ended December 31, 2022 2021 2020 Amount % of Pretax Amount % of Pretax Amount % of Pretax Federal statutory rate $ 278.7 21.0 $ 204.8 21.0 $ 182.9 21.0 State income taxes - net of 32.9 2.5 30.7 3.2 22.2 2.6 Differences related to non U.S. operations ( 31.9 ) ( 2.4 ) ( 8.7 ) ( 0.9 ) ( 2.5 ) ( 0.3 ) Alternative energy and other ( 6.9 ) ( 0.5 ) ( 199.0 ) ( 20.4 ) ( 154.3 ) ( 17.7 ) Other permanent differences 22.5 1.7 ( 3.5 ) ( 0.4 ) ( 15.7 ) ( 1.8 ) Stock-based compensation ( 59.3 ) ( 4.5 ) ( 40.0 ) ( 4.1 ) ( 31.4 ) ( 3.6 ) Changes in unrecognized tax benefits 4.0 0.3 0.8 0.1 — — Change in valuation allowance 15.5 1.2 26.4 2.7 6.5 0.7 Change in tax rates ( 44.5 ) ( 3.4 ) 8.6 0.9 5.5 0.6 Other — — — — ( 0.4 ) — Provision for income taxes $ 211.0 $ 15.9 $ 20.1 $ 2.1 $ 12.8 $ 1.5
Gross Unrecognized Tax Benefits	A reconciliation of the beginning and ending balances of the total amounts of gross unrecognized tax benefits is as follows (in millions): December 31, 2022 2021 Gross unrecognized tax benefits at January 1 $ 11.7 $ 11.2 Increases in tax positions for current year 3.8 2.5 Settlements ( 1.7 ) — Lapse in statute of limitations ( 1.4 ) ( 1.6 ) Increases in tax positions for prior years 3.1 0.1 Decreases in tax positions for prior years ( 2.1 ) ( 0.5 ) Gross unrecognized tax benefits at December 31 $ 13.4 $ 11.7
Deferred Tax Assets and Liabilities	Significant components of our deferred tax assets and liabilities are as follows (in millions): December 31, 2022 2021 Deferred tax assets: Alternative minimum tax and other credit carryforwards $ 772.7 $ 1,074.0 Accrued and unfunded compensation and employee benefits 321.8 265.6 Amortizable intangible assets 69.3 92.7 Compensation expense related to stock options 11.1 5.8 Accrued liabilities 126.6 112.1 Accrued pension liability 3.1 1.5 Investments 2.6 3.1 Net operating loss carryforwards 129.4 32.7 Capital loss carryforwards 8.1 8.9 Lease liabilities 96.5 106.4 Capitalized indirect property costs 394.1 — Hedging instruments — 27.3 Other 4.3 5.0 Total deferred tax assets 1,939.6 1,735.1 Valuation allowance for deferred tax assets ( 135.2 ) ( 154.9 ) Deferred tax assets 1,804.4 1,580.2 Deferred tax liabilities: Nondeductible amortizable intangible assets 433.9 394.7 Investment-related partnerships 6.6 4.6 Depreciable fixed assets 46.5 16.2 Right-of-use assets 88.6 96.9 Hedging instruments 10.7 — Other prepaid items 11.8 8.8 Total deferred tax liabilities 598.1 521.2 Net deferred tax assets $ 1,206.3 $ 1,059.0

Supplemental Disclosures of C_2

Supplemental Disclosures of Cash Flow Information (Tables)	12 Months Ended
Supplemental Disclosures of Cash Flow Information (Tables)	Dec. 31, 2022
Cash and Cash Equivalents [Abstract]
Supplemental Disclosures of Cash Flow Information	Year ended December 31, Supplemental disclosures of cash flow information (in millions): 2022 2021 2020 Interest paid $ 240.2 $ 215.7 $ 188.9 Income taxes paid, net 317.6 325.4 113.0
Summary of Cash, Cash Equivalents and Restricted Cash	The following is a reconciliation of our end of period cash, cash equivalents and restricted cash balances as presented in the consolidated statement of cash flows for the years ended December 31, 2022, 2021 and 2020 (in millions): December 31, 2022 2021 2020 Cash and cash equivalents $ 342.3 $ 402.6 $ 664.6 Restricted cash 4,621.9 4,063.7 2,909.7 Total cash, cash equivalents and restricted cash $ 4,964.2 $ 4,466.3 $ 3,574.3

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
Accumulated Other Comprehensive Loss (Tables)	Dec. 31, 2022
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Loss Attributable to Controlling Interests	The after-tax components of our accumulated comprehensive loss attributable to controlling interests consist of the following (in millions): Pension Foreign Fair Value Accumulated Balance as of January 1, 2020 $ ( 56.5 ) $ ( 674.8 ) $ ( 28.3 ) $ ( 759.6 ) Net change in period 0.4 183.7 ( 68.1 ) 116.0 Balance as of December 31, 2020 ( 56.1 ) ( 491.1 ) ( 96.4 ) ( 643.6 ) Net change in period 19.0 ( 122.3 ) 20.8 ( 82.5 ) Balance as of December 31, 2021 ( 37.1 ) ( 613.4 ) ( 75.6 ) ( 726.1 ) Net change in period ( 12.3 ) ( 511.8 ) 109.8 ( 414.3 ) Balance as of December 31, 2022 $ ( 49.4 ) $ ( 1,125.2 ) $ 34.2 $ ( 1,140.4 )

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
Segment Information (Tables)	Dec. 31, 2022
Segment Reporting [Abstract]
Schedule of Segment Reporting Information by Segment	Financial information relating to our segments for 2022, 2021 and 2020 is as follows (in millions): Year Ended December 31, 2022 Brokerage Risk Corporate Total Revenues: Commissions $ 5,187.4 $ — $ — $ 5,187.4 Fees 1,476.9 1,090.8 — 2,567.7 Supplemental revenues 284.7 — — 284.7 Contingent revenues 207.3 — — 207.3 Investment income 135.4 0.9 — 136.3 Net gains on divestitures 12.1 0.9 — 13.0 Revenue from clean coal activities — — 23.0 23.0 Other net income — — 0.7 0.7 Revenues before reimbursements 7,303.8 1,092.6 23.7 8,420.1 Reimbursements — 130.5 — 130.5 Total revenues 7,303.8 1,223.1 23.7 8,550.6 Compensation 4,024.7 664.9 110.2 4,799.8 Operating 1,039.9 233.9 57.1 1,330.9 Reimbursements — 130.5 — 130.5 Cost of revenues from clean coal activities — — 22.9 22.9 Interest — — 256.9 256.9 Depreciation 103.6 37.8 3.3 144.7 Amortization 448.7 6.2 — 454.9 Change in estimated acquisition earnout payables 90.4 ( 7.4 ) — 83.0 Total expenses 5,707.3 1,065.9 450.4 7,223.6 Earnings (loss) before income taxes 1,596.5 157.2 ( 426.7 ) 1,327.0 Provision (benefit) for income taxes 394.7 41.4 ( 225.1 ) 211.0 Net earnings (loss) 1,201.8 115.8 ( 201.6 ) 1,116.0 Net earnings (loss) attributable to noncontrolling interests 4.4 — ( 2.6 ) 1.8 Net earnings (loss) attributable to controlling interests $ 1,197.4 $ 115.8 $ ( 199.0 ) $ 1,114.2 Net foreign exchange gain $ 2.6 $ 31.4 $ — $ 34.0 Revenues: United States $ 4,503.9 $ 1,029.6 $ 23.7 $ 5,557.2 United Kingdom 1,544.3 44.1 — 1,588.4 Australia 281.8 129.1 — 410.9 Canada 356.0 5.9 — 361.9 New Zealand 166.9 14.4 — 181.3 Other foreign 450.9 — — 450.9 Total revenues $ 7,303.8 $ 1,223.1 $ 23.7 $ 8,550.6 At December 31, 2022 Identifiable assets: United States $ 17,827.2 $ 914.4 $ 2,560.2 $ 21,301.8 United Kingdom 9,486.6 115.9 — 9,602.5 Australia 1,797.9 89.0 — 1,886.9 Canada 1,476.4 4.4 — 1,480.8 New Zealand 731.0 18.8 — 749.8 Other foreign 3,886.0 — — 3,886.0 Total identifiable assets $ 35,205.1 $ 1,142.5 $ 2,560.2 $ 38,907.8 Goodwill - net $ 9,358.1 $ 112.2 $ 19.1 $ 9,489.4 Amortizable intangible assets - net 3,325.9 46.2 — 3,372.1 Year Ended December 31, 2021 Brokerage Risk Corporate Total Revenues: Commissions $ 4,132.3 $ — $ — $ 4,132.3 Fees 1,296.9 967.2 — 2,264.1 Supplemental revenues 248.7 — — 248.7 Contingent revenues 188.0 — — 188.0 Investment income 82.8 0.3 — 83.1 Net gains on divestitures 18.8 0.1 — 18.9 Revenue from clean coal activities — — 1,140.8 1,140.8 Other net revenues — — 0.5 0.5 Revenues before reimbursements 5,967.5 967.6 1,141.3 8,076.4 Reimbursements — 133.0 — 133.0 Total revenues 5,967.5 1,100.6 1,141.3 8,209.4 Compensation 3,252.4 580.7 94.4 3,927.5 Operating 757.9 209.8 104.7 1,072.4 Reimbursements — 133.0 — 133.0 Cost of revenues from clean coal activities — — 1,173.2 1,173.2 Interest — — 226.1 226.1 Loss on extinguishment of debt — — 16.2 16.2 Depreciation 87.8 46.2 17.2 151.2 Amortization 407.6 7.5 — 415.1 Change in estimated acquisition earnout payables 116.3 3.3 — 119.6 Total expenses 4,622.0 980.5 1,631.8 7,234.3 Earnings (loss) before income taxes 1,345.5 120.1 ( 490.5 ) 975.1 Provision (benefit) for income taxes 328.9 30.6 ( 339.4 ) 20.1 Net earnings (loss) 1,016.6 89.5 ( 151.1 ) 955.0 Net earnings attributable to noncontrolling interests 8.4 — 39.8 48.2 Net earnings (loss) attributable to controlling interests $ 1,008.2 $ 89.5 $ ( 190.9 ) $ 906.8 Net foreign exchange loss $ ( 1.7 ) $ — $ ( 0.6 ) $ ( 2.3 ) Revenues: United States $ 3,804.8 $ 910.7 $ 1,141.3 $ 5,856.8 United Kingdom 1,199.0 46.0 — 1,245.0 Australia 252.6 123.5 — 376.1 Canada 302.2 5.8 — 308.0 New Zealand 162.4 14.6 — 177.0 Other foreign 246.5 — — 246.5 Total revenues $ 5,967.5 $ 1,100.6 $ 1,141.3 $ 8,209.4 At December 31, 2021 Identifiable assets: United States $ 15,548.3 $ 790.7 $ 2,489.6 $ 18,828.6 United Kingdom 8,251.3 134.1 — 8,385.4 Australia 1,684.2 84.7 — 1,768.9 Canada 1,436.1 4.4 — 1,440.5 New Zealand 754.5 20.5 — 775.0 Other foreign 2,146.6 — — 2,146.6 Total identifiable assets $ 29,821.0 $ 1,034.4 $ 2,489.6 $ 33,345.0 Goodwill - net $ 8,544.6 $ 100.9 $ 20.7 $ 8,666.2 Amortizable intangible assets - net 3,906.1 47.9 — 3,954.0 Year Ended December 31, 2020 Brokerage Risk Corporate Total Revenues: Commissions $ 3,591.9 $ — $ — $ 3,591.9 Fees 1,136.9 821.0 — 1,957.9 Supplemental revenues 221.9 — — 221.9 Contingent revenues 147.0 — — 147.0 Investment income 75.2 0.7 — 75.9 Net losses on divestitures ( 5.8 ) — — ( 5.8 ) Revenue from clean coal activities — — 863.5 863.5 Other net losses — — ( 0.4 ) ( 0.4 ) Revenues before reimbursements 5,167.1 821.7 863.1 6,851.9 Reimbursements — 151.7 — 151.7 Total revenues 5,167.1 973.4 863.1 7,003.6 Compensation 2,882.5 517.5 66.5 3,466.5 Operating 687.2 162.6 56.7 906.5 Reimbursements — 151.7 — 151.7 Cost of revenues from clean coal activities — — 882.1 882.1 Interest — — 196.4 196.4 Depreciation 73.5 49.4 22.2 145.1 Amortization 411.3 6.0 — 417.3 Change in estimated acquisition earnout payables ( 29.7 ) ( 3.2 ) — ( 32.9 ) Total expenses 4,024.8 884.0 1,223.9 6,132.7 Earnings (loss) before income taxes 1,142.3 89.4 ( 360.8 ) 870.9 Provision (benefit) for income taxes 276.3 22.5 ( 286.0 ) 12.8 Net earnings (loss) 866.0 66.9 ( 74.8 ) 858.1 Net earnings attributable to noncontrolling interests 4.9 — 34.4 39.3 Net earnings (loss) attributable to controlling interests $ 861.1 $ 66.9 $ ( 109.2 ) $ 818.8 Net foreign exchange loss $ ( 2.6 ) $ ( 0.1 ) $ ( 0.2 ) $ ( 2.9 ) Revenues: United States $ 3,369.4 $ 816.4 $ 863.1 $ 5,048.9 United Kingdom 993.7 40.7 — 1,034.4 Australia 216.1 98.4 — 314.5 Canada 243.8 5.3 — 249.1 New Zealand 141.8 12.6 — 154.4 Other foreign 202.3 — — 202.3 Total revenues $ 5,167.1 $ 973.4 $ 863.1 $ 7,003.6 At December 31, 2020 Identifiable assets: United States $ 8,897.9 $ 716.2 $ 2,172.2 $ 11,786.3 United Kingdom 6,135.1 139.2 — 6,274.3 Australia 1,373.3 89.6 — 1,462.9 Canada 1,053.6 4.8 — 1,058.4 New Zealand 766.0 24.1 — 790.1 Other foreign 959.4 — — 959.4 Total identifiable assets $ 19,185.3 $ 973.9 $ 2,172.2 $ 22,331.4 Goodwill - net $ 6,053.6 $ 70.5 $ 2.9 $ 6,127.0 Amortizable intangible assets - net 2,376.3 23.6 — 2,399.9

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2022 USD ($) Country Segment Facility shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($)
Significant Accounting Policies [Line Items]
Number of reportable segments \| Segment	3
Number of commercial clean coal production facilities \| Facility	35
Number of countries in which the company does business through a network of correspondent brokers and consultants \| Country	130
Percentage of variable ownership interest	50%
Description of contracts renewal period	one year or less
Percentage of commission and fee revenues on the effective date	80%
Percentage of commission and fee revenues in the first three months	15%
Percentage of commission and fee revenues after the first three months	5%
Allowances for estimated policy cancellations	$ 9,300,000	$ 10,000,000
Allowance for doubtful accounts	$ 11,100,000	8,300,000
Premium financing contracts, terms	premium financing contracts are structured to minimize potential bad debt expense to us. Such receivables are generally considered delinquent after seven days of the payment due date. In normal course, insurance policies are canceled within one month of the contractual payment due date if the payment remains delinquent.
Outstanding loan receivable	$ 546,300,000	509,700,000
Write-off of amortizable intangible assets	$ 2,000,000	$ 17,600,000	$ 51,700,000
Impairment, Intangible Asset, Finite-Lived, Statement of Income or Comprehensive Income [Extensible Enumeration]	Depreciation, Amortization and Accretion, Net	Depreciation, Amortization and Accretion, Net	Depreciation, Amortization and Accretion, Net
Employee Stock Purchase Plan [Member]
Significant Accounting Policies [Line Items]
Shares authorized \| shares	8,000,000
Percentage of employees contribution	15%
Purchase price of common stock, percentage	95%
Aggregate fair market value of shares purchased	$ 25,000
Maximum number of shares purchased by employees \| shares		2,000
Shares available for grant \| shares	5,300,000
Maximum [Member] \| Partially Owned Entities [Member]
Significant Accounting Policies [Line Items]
Percentage of ownership interest	50%
Maximum [Member] \| Expiration Lists [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	15 years
Maximum [Member] \| Non-Compete Agreements [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	6 years
Maximum [Member] \| Trade Names [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	15 years
Minimum [Member] \| Majority-owned Subsidiaries [Member]
Significant Accounting Policies [Line Items]
Percentage of ownership interest	50%
Minimum [Member] \| Expiration Lists [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	2 years
Minimum [Member] \| Non-Compete Agreements [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	2 years
Minimum [Member] \| Trade Names [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of intangibles assets, years	2 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Estimated Useful Life of Fixed Assets (Detail)	12 Months Ended
	Dec. 31, 2022
Office Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	3 years
Office Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	10 years
Furniture and Fixtures [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	3 years
Furniture and Fixtures [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	10 years
Computer Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	3 years
Computer Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	5 years
Building [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	15 years
Building [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	40 years
Software [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	3 years
Software [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	5 years
Refined Fuel Plants [Member]
Property, Plant and Equipment [Line Items]
Useful life, years	10 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives, years	Shorter of the lease term or useful life of the asset

Business Combinations - Acquisi

Business Combinations - Acquisition Method for Recording Business Combinations (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) shares
Devitt Insurance Services Ltd [Member]
Business Acquisition [Line Items]
Cash Paid	$ 73,600,000
Accrued Liability	1,300,000
Escrow Deposited	3,400,000
Recorded Earnout Payable	12,600,000
Total Recorded Purchase Price	90,900,000
Maximum Potential Earnout Payable	12,500,000
Innovu Group Holding Company Limited [Member]
Business Acquisition [Line Items]
Cash Paid	85,400,000
Total Recorded Purchase Price	$ 85,400,000
F3 Companies [Member]
Business Acquisition [Line Items]
Common Shares Issued \| shares	352
Common Share Value	$ 61,700,000
Cash Paid	33,100,000
Escrow Deposited	5,000,000
Recorded Earnout Payable	6,100,000
Total Recorded Purchase Price	105,900,000
Maximum Potential Earnout Payable	25,000,000
M&T Insurance Agency [Member]
Business Acquisition [Line Items]
Cash Paid	171,000,000
Total Recorded Purchase Price	$ 171,000,000
PIUS Limited LLC [Member]
Business Acquisition [Line Items]
Common Shares Issued \| shares	74
Common Share Value	$ 10,600,000
Cash Paid	35,600,000
Escrow Deposited	3,800,000
Recorded Earnout Payable	116,400,000
Total Recorded Purchase Price	166,400,000
Maximum Potential Earnout Payable	$ 150,000,000
Thirty-Two Other Acquisitions [Member]
Business Acquisition [Line Items]
Common Shares Issued \| shares	300
Common Share Value	$ 50,600,000
Cash Paid	457,200,000
Accrued Liability	41,700,000
Escrow Deposited	27,000,000
Recorded Earnout Payable	106,900,000
Total Recorded Purchase Price	683,400,000
Maximum Potential Earnout Payable	$ 230,200,000
2022 Acquisitions [Member]
Business Acquisition [Line Items]
Common Shares Issued \| shares	726
Common Share Value	$ 122,900,000
Cash Paid	855,900,000
Accrued Liability	43,000,000
Escrow Deposited	39,200,000
Recorded Earnout Payable	242,000,000
Total Recorded Purchase Price	1,303,000,000
Maximum Potential Earnout Payable	$ 417,700,000

Business Combinations - Additio

Business Combinations - Additional Information (Detail)			12 Months Ended
Business Combinations - Additional Information (Detail)	Dec. 20, 2022 USD ($) Employee	Dec. 01, 2021 USD ($) BrokerageOperation	Dec. 31, 2022 USD ($) Entity Employee	Dec. 31, 2021 USD ($) Entity	Dec. 31, 2020 USD ($) Entity
Business Acquisition [Line Items]
Net cash raised through follow-on public offering common stock			$ 123,100,000	$ 1,546,700,000	$ 111,900,000
Accretion of the discount on acquisition			61,000,000	35,700,000	32,500,000
Income (expense) related to net adjustments to estimated fair value of liability for earnout obligations			$ (22,000,000)	$ (83,900,000)	$ 65,400,000
Number of companies acquired \| Entity			89	99	135
Aggregate amount of maximum earnout obligations related to acquisitions			$ 1,946,200,000	$ 1,873,900,000
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet			1,077,300,000	988,500,000
Aggregate amount of earnout obligation expected settlement in cash or stock at option			734,000,000	670,300,000
Aggregate amount of earnout obligation expected settlement in cash			343,300,000	318,200,000
Goodwill			709,900,000
Expiration lists			564,000,000
Non-compete agreements			19,500,000
Trade names			6,100,000
Write-off of amortizable intangible assets			2,000,000	17,600,000	$ 51,700,000
Total revenues			8,710,200,000	8,445,800,000
Goodwill			$ 9,489,400,000	8,666,200,000	6,127,000,000
Number of employees \| Employee			2,000
Revision of Prior Period, Adjustment [Member]
Business Acquisition [Line Items]
Expiration lists			$ (608,000,000)
Increase in acquired software			59,100,000
Fair value of earnout liability			(1,600,000)
Working capital adjustment			106,000,000
Goodwill			441,300,000
Brokerage Management [Member]
Business Acquisition [Line Items]
Goodwill			709,900,000
Expiration lists			564,000,000
Non-compete agreements			19,500,000
Trade names			6,100,000
Brokerage and Risk Management [Member]
Business Acquisition [Line Items]
Write-off of amortizable intangible assets			2,000,000	17,600,000	51,700,000
Brokerage [Member]
Business Acquisition [Line Items]
Goodwill			9,358,100,000	$ 8,544,600,000	$ 6,053,600,000
Brokerage [Member] \| Expiration Lists [Member]
Business Acquisition [Line Items]
Business acquisition not deductible for income tax purposes			127,800,000
Brokerage [Member] \| Non-Compete Agreements [Member]
Business Acquisition [Line Items]
Business acquisition not deductible for income tax purposes			8,500,000
Brokerage [Member] \| Trade Names [Member]
Business Acquisition [Line Items]
Business acquisition not deductible for income tax purposes			$ 2,000,000
Minimum [Member] \| Expiration Lists [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			2 years
Minimum [Member] \| Non-Compete Agreements [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			2 years
Minimum [Member] \| Trade Names [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			2 years
Maximum [Member] \| Expiration Lists [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			15 years
Maximum [Member] \| Non-Compete Agreements [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			6 years
Maximum [Member] \| Trade Names [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			15 years
Willis Towers Watson PLC [Member]
Business Acquisition [Line Items]
Initial gross consideration		$ 3,170,000,000
Potential additional consideration subject to certain revenue targets		$ 750,000,000
Number of remaining international deferred closings \| BrokerageOperation		12
Initial purchase consideration subject to local regulatory approval		$ 180,000,000
2021 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input			0.030
2021 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input			0.052
2021 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Attrition rate			5.50%
2021 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Attrition rate			9.50%
2021 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input			0.100
2021 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input			0.165
Business Acquisition [Member]
Business Acquisition [Line Items]
Annualized revenue of business acquisitions			$ 246,500,000
Total revenues			87,900,000
Net earnings			(700,000)
Business Acquisition [Member] \| Brokerage [Member]
Business Acquisition [Line Items]
Expiration lists			564,000,000
Non-compete agreements			19,500,000
Deferred tax liability			29,600,000
2022 Acquisitions [Member]
Business Acquisition [Line Items]
Trade names			$ 6,100,000
2022 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Discount Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input			3
2022 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Discount Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input			18.5
2022 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input			0.030
2022 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input			0.052
2022 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Attrition rate			5.50%
2022 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Attrition rate			9.50%
2022 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Discount Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input			0.075
2022 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Discount Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input			0.108
2022 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input			0.100
2022 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input			0.165
BCHR Holdings, L.P. [Member]
Business Acquisition [Line Items]
Initial gross consideration	$ 660,000,000
Net of agreed seller funded expenses and net working capital	$ 585,000,000
Number of employees \| Employee	2,300
Number of credentialed actuaries \| Employee	220
BCHR Holdings, L.P. [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Business combination period of existence	100 years

Business Combinations - Summary

Business Combinations - Summary of Estimated Fair Values of Net Assets Acquired (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash and restricted cash	$ 51.5
Other current assets	126.6
Fixed assets	3.2
Noncurrent assets	17.5
Goodwill	709.9
Expiration lists	564
Non-compete agreements	19.5
Trade names	6.1
Total assets acquired	1,498.3
Current liabilities	150.3
Noncurrent liabilities	45
Total liabilities assumed	195.3
Total net assets acquired	1,303
DIS [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash and restricted cash	3.9
Other current assets	18.5
Fixed assets	0.4
Noncurrent assets	1.3
Goodwill	60.4
Expiration lists	29
Non-compete agreements	0.7
Trade names	0.9
Total assets acquired	115.1
Current liabilities	15.3
Noncurrent liabilities	8.9
Total liabilities assumed	24.2
Total net assets acquired	90.9
IGH [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash and restricted cash	7.8
Other current assets	6.5
Fixed assets	0.5
Noncurrent assets	2
Goodwill	47.2
Expiration lists	35
Non-compete agreements	4
Trade names	0.8
Total assets acquired	103.8
Current liabilities	11.2
Noncurrent liabilities	7.2
Total liabilities assumed	18.4
Total net assets acquired	85.4
F3 Companies [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Other current assets	0.1
Noncurrent assets	1.8
Goodwill	40.5
Expiration lists	65.1
Non-compete agreements	0.2
Total assets acquired	107.7
Current liabilities	0.3
Noncurrent liabilities	1.5
Total liabilities assumed	1.8
Total net assets acquired	105.9
M&T
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash and restricted cash	6.1
Other current assets	27.6
Fixed assets	0.2
Noncurrent assets	1.4
Goodwill	87
Expiration lists	78.9
Non-compete agreements	0.9
Total assets acquired	202.1
Current liabilities	30.2
Noncurrent liabilities	0.9
Total liabilities assumed	31.1
Total net assets acquired	171
PIU
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash and restricted cash	2.8
Goodwill	116.4
Expiration lists	44.6
Non-compete agreements	1
Trade names	4
Total assets acquired	168.8
Current liabilities	2.4
Total liabilities assumed	2.4
Total net assets acquired	166.4
Thirty-Two Other Acquisitions [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Cash and restricted cash	30.9
Other current assets	73.9
Fixed assets	2.1
Noncurrent assets	11
Goodwill	358.4
Expiration lists	311.4
Non-compete agreements	12.7
Trade names	0.4
Total assets acquired	800.8
Current liabilities	90.9
Noncurrent liabilities	26.5
Total liabilities assumed	117.4
Total net assets acquired	$ 683.4

Business Combinations - Summa_2

Business Combinations - Summary of Unaudited Pro Forma Historical Results (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Business Combinations [Abstract]
Total revenues	$ 8,710.2	$ 8,445.8
Net earnings attributable to controlling interests	$ 1,114.8	$ 907.1
Basic net earnings per share	$ 5.29	$ 4.46
Diluted net earnings per share	$ 5.18	$ 4.36

Contracts with Customers - Summ

Contracts with Customers - Summary of Unbilled Receivables, Contract Assets and Contract Liabilities from Contracts with Customers (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract]
Unbilled receivables	$ 910.9	$ 730
Deferred contract costs	144.5	129.7
Deferred revenue	$ 609.3	$ 579.6	$ 541.3

Contracts with Customers - Su_2

Contracts with Customers - Summary of Changes in Deferred Revenue Balances (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Deferred Revenue Arrangement [Line Items]
Deferred revenue beginning balance	$ 579.6	$ 541.3
Incremental deferred revenue	445.5	427.1
Revenue recognized	(430.9)	(399.6)
Net change in collected billings/deposits received from customers	14.4	(4.3)
Impact of changes in foreign exchange rates	(17.9)	(4.5)
Deferred revenue recognized from business acquisitions	18.6	19.6
Deferred revenue ending balance	609.3	579.6
Brokerage [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenue beginning balance	395.9	354.7
Incremental deferred revenue	342.3	325
Revenue recognized	(326.3)	(296.1)
Net change in collected billings/deposits received from customers	21.4	(3.6)
Impact of changes in foreign exchange rates	(17.9)	(3.7)
Deferred revenue recognized from business acquisitions	18.6	19.6
Deferred revenue ending balance	434	395.9
Risk Management [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenue beginning balance	183.7	186.6
Incremental deferred revenue	103.2	102.1
Revenue recognized	(104.6)	(103.5)
Net change in collected billings/deposits received from customers	(7)	(0.7)
Impact of changes in foreign exchange rates		(0.8)
Deferred revenue ending balance	$ 175.3	$ 183.7

Contracts with Customers - Addi

Contracts with Customers - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Remaining performance obligations	$ 609.3
Deferred contract costs	144.5	$ 129.7
Amortization of deferred contract costs	$ 504.4	$ 425.5

Contracts with Customers - Su_3

Contracts with Customers - Summary of Expected Revenue Related to Performance Obligations (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 609.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 453
Remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 90.8
Remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 28.6
Remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 15.2
Remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 8.9
Remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 12.8
Remaining performance obligation, expected timing of satisfaction, period
Brokerage [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 434
Brokerage [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 404.6
Remaining performance obligation, expected timing of satisfaction, period	1 year
Brokerage [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 26.3
Remaining performance obligation, expected timing of satisfaction, period	1 year
Brokerage [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 1.4
Remaining performance obligation, expected timing of satisfaction, period	1 year
Brokerage [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 0.8
Remaining performance obligation, expected timing of satisfaction, period	1 year
Brokerage [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 0.5
Remaining performance obligation, expected timing of satisfaction, period	1 year
Brokerage [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 0.4
Remaining performance obligation, expected timing of satisfaction, period
Risk Management [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 175.3
Risk Management [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 48.4
Remaining performance obligation, expected timing of satisfaction, period	1 year
Risk Management [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 64.5
Remaining performance obligation, expected timing of satisfaction, period	1 year
Risk Management [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 27.2
Remaining performance obligation, expected timing of satisfaction, period	1 year
Risk Management [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 14.4
Remaining performance obligation, expected timing of satisfaction, period	1 year
Risk Management [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 8.4
Remaining performance obligation, expected timing of satisfaction, period	1 year
Risk Management [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 12.4
Remaining performance obligation, expected timing of satisfaction, period

Contracts with Customers - Su_4

Contracts with Customers - Summary of Expected Revenue Related to Performance Obligations 1 (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 609.3
Brokerage [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	434
Risk Management [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Expected revenue related to performance obligations	$ 175.3

Other Financial Data - Summary

Other Financial Data - Summary of Major Classes of Other Current Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Premium finance advances and loans	$ 546.3	$ 509.7
Accrued supplemental, direct bill and other receivables	567.8	563
Refined coal production related receivables	5.7	76.9
Deferred contract costs	144.5	129.7
Prepaid expenses	197.2	171.7
Total other current assets	$ 1,461.5	$ 1,451

Fixed Assets - Summary of Fixed

Fixed Assets - Summary of Fixed Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment Useful Life And Values [Abstract]
Office equipment	$ 32.2	$ 36.2
Furniture and fixtures	142	137.1
Leasehold improvements	190.7	170.8
Computer equipment	295.8	247.1
Land and buildings - corporate headquarters	145.3	145.3
Software	583.4	532.2
Other	16.9	17.2
Work in process	56	23
Gross fixed assets	1,462.3	1,308.9
Accumulated depreciation	(886.1)	(808.1)
Net fixed assets	$ 576.2	$ 500.8

Intangible Assets - Carrying Am

Intangible Assets - Carrying Amount of Goodwill Allocated by Domestic and Foreign Operations (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Line Items]
Total goodwill - net	$ 9,489.4	$ 8,666.2	$ 6,127
Unites States [Member]
Goodwill [Line Items]
Total goodwill - net	5,140.5	4,473.9
United Kingdom [Member]
Goodwill [Line Items]
Total goodwill - net	2,197.9	2,213.7
Canada [Member]
Goodwill [Line Items]
Total goodwill - net	569.7	572.9
Australia [Member]
Goodwill [Line Items]
Total goodwill - net	477.8	498.1
New Zealand [Member]
Goodwill [Line Items]
Total goodwill - net	213.3	227.8
Other Foreign [Member]
Goodwill [Line Items]
Total goodwill - net	890.2	679.8
Brokerage [Member]
Goodwill [Line Items]
Total goodwill - net	9,358.1	8,544.6	6,053.6
Brokerage [Member] \| Unites States [Member]
Goodwill [Line Items]
Total goodwill - net	5,065.7	4,409.1
Brokerage [Member] \| United Kingdom [Member]
Goodwill [Line Items]
Total goodwill - net	2,180.2	2,198.7
Brokerage [Member] \| Canada [Member]
Goodwill [Line Items]
Total goodwill - net	569.7	572.9
Brokerage [Member] \| Australia [Member]
Goodwill [Line Items]
Total goodwill - net	467.6	487.2
Brokerage [Member] \| New Zealand [Member]
Goodwill [Line Items]
Total goodwill - net	203.8	217.6
Brokerage [Member] \| Other Foreign [Member]
Goodwill [Line Items]
Total goodwill - net	871.1	659.1
Risk Management [Member]
Goodwill [Line Items]
Total goodwill - net	112.2	100.9	70.5
Risk Management [Member] \| Unites States [Member]
Goodwill [Line Items]
Total goodwill - net	74.8	64.8
Risk Management [Member] \| United Kingdom [Member]
Goodwill [Line Items]
Total goodwill - net	17.7	15
Risk Management [Member] \| Australia [Member]
Goodwill [Line Items]
Total goodwill - net	10.2	10.9
Risk Management [Member] \| New Zealand [Member]
Goodwill [Line Items]
Total goodwill - net	9.5	10.2
Corporate [Member]
Goodwill [Line Items]
Total goodwill - net	19.1	20.7	$ 2.9
Corporate [Member] \| Other Foreign [Member]
Goodwill [Line Items]
Total goodwill - net	$ 19.1	$ 20.7

Intangible Assets - Changes in

Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Beginning Balance	$ 8,666.2	$ 6,127
Goodwill acquired during the year	709.9	2,561.5
Goodwill adjustments related to appraisals and other acquisition adjustments	426.9	50.8
Goodwill written-off related to sales of business		(1)
Foreign currency translation adjustments during the year	(313.6)	(72.1)
Ending Balance	9,489.4	8,666.2
Brokerage [Member]
Goodwill [Line Items]
Beginning Balance	8,544.6	6,053.6
Goodwill acquired during the year	693.9	2,511.8
Goodwill adjustments related to appraisals and other acquisition adjustments	428.3	50.8
Goodwill written-off related to sales of business		(1)
Foreign currency translation adjustments during the year	(308.7)	(70.6)
Ending Balance	9,358.1	8,544.6
Risk Management [Member]
Goodwill [Line Items]
Beginning Balance	100.9	70.5
Goodwill acquired during the year	16	31.6
Goodwill adjustments related to appraisals and other acquisition adjustments	(1.6)
Foreign currency translation adjustments during the year	(3.1)	(1.2)
Ending Balance	112.2	100.9
Corporate [Member]
Goodwill [Line Items]
Beginning Balance	20.7	2.9
Goodwill acquired during the year		18.1
Goodwill adjustments related to appraisals and other acquisition adjustments	0.2
Foreign currency translation adjustments during the year	(1.8)	(0.3)
Ending Balance	$ 19.1	$ 20.7

Intangible Assets - Major Class

Intangible Assets - Major Classes of Amortizable Intangible Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, net	$ 3,372.1	$ 3,954
Expiration Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	6,472.3	6,696.8
Accumulated amortization	(3,178.5)	(2,812.2)
Amortizable intangible assets, net	3,293.8	3,884.6
Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	91.3	76
Accumulated amortization	(67.5)	(62.8)
Amortizable intangible assets, net	23.8	13.2
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	108.5	105.2
Accumulated amortization	(54)	(49)
Amortizable intangible assets, net	$ 54.5	$ 56.2

Intangible Assets - Estimated A

Intangible Assets - Estimated Aggregate Amortization Expense (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
2023	$ 466.1
2024	429.5
2025	388.5
2026	349.7
2027	320.3
Thereafter	1,418
Amortizable intangible assets, net	$ 3,372.1	$ 3,954

Credit and Other Debt Agreeme_3

Credit and Other Debt Agreements - Summary of Corporate and Other Debt (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Semi-annual payments of interest	$ 6,149.9	$ 6,321.4
Less unamortized debt acquisition costs on Senior Notes and Note Purchase Agreements	(20.6)	(22.6)
Less unamortized discount on Bonds Payable	(14.6)	(15.2)
Semi-annual payments of interest, Net	6,114.7	6,283.6
Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	4,248	4,448
Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	1,600	1,600
Fixed Rate of 2.40%, Balloon Due November 9, 2031 [Member] \| Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	400	400
Fixed Rate of 3.50%, Balloon Due May 20, 2051 [Member] \| Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	850	850
Fixed Rate of 3.05%, Balloon Due March 9, 2052 [Member] \| Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	350	350
Fixed Rate of 3.69%, Balloon Due June 14, 2022 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest		200
Fixed Rate of 5.49%, Balloon Due February 10, 2023 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 4.13%, Balloon Due June 24, 2023 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	200	200
Fixed Rate of 4.72%, Balloon due February 13, 2024 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	100	100
Fixed Rate of 4.58%, Balloon Due February 27, 2024 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	325	325
Floating Interest Rate of 1.40% LIBOR Plus Balloon Due June 13, 2024 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 4.31%, Balloon Due June 24, 2025 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	200	200
Fixed Rate of 4.85%, Balloon due February 13, 2026 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	140	140
Fixed Rate of 4.73%, Balloon Due February 27, 2026 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	175	175
Fixed Rate of 4.40%, Balloon Due June 2, 2026 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	175	175
Fixed Rate of 4.36%, Balloon Due June 24, 2026 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	150	150
Fixed Rate of 3.75%, Balloon Due January 30, 2027 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	30	30
Fixed Rate of 4.09%, Balloon Due June 27, 2027 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	125	125
Fixed Rate of 4.09%, Balloon Due August 2, 2027 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	125	125
Fixed Rate of 4.14%, Balloon Due August 4, 2027 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	98	98
Fixed Rate of 3.46%, Balloon Due December 1, 2027 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	100	100
Fixed Rate of 4.55%, Balloon Due June 2, 2028 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	75	75
Fixed Rate of 4.34%, Balloon due June 13, 2028 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	125	125
Fixed Rate of 5.04%, Balloon due February 13, 2029 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	100	100
Fixed Rate of 4.98%, Balloon Due February 27, 2029 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	100	100
Fixed Rate of 4.19%, Balloon Due June 27, 2029 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 4.19%, Balloon Due August 2, 2029 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 3.48%, Balloon Due December 2, 2029 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	50	50
Fixed Rate of 3.99%, Balloon Due January 30, 2030 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	341	341
Fixed Rate of 4.44%, Balloon Due June 13, 2030 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	125	125
Fixed Rate of 5.14%, Balloon due March 13, 2031 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	180	180
Fixed Rate of 4.70%, Balloon Due June 2, 2031 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	25	25
Fixed Rate of 4.09%, Balloon Due January 30, 2032 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	69	69
Fixed Rate of 4.34%, Balloon Due June 27, 2032 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	75	75
Fixed Rate of 4.34%, Balloon Due August 2, 2032 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	75	75
Fixed Rate of 4.59%, Balloon due June 13, 2033 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	125	125
Fixed Rate of 5.29%, balloon due March 13, 2034 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	40	40
Fixed Rate of 4.48%, Balloon Due June 12, 2034 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	175	175
Fixed Rate of 4.24%, Balloon Due January 30, 2035 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	79	79
Fixed Rate of 2.44%, Balloon Due February 10, 2036 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	100	100
Fixed Rate of 2.46%, Balloon Due May 5, 2036 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	75	75
Fixed Rate of 4.69%, Balloon Due June 13, 2038 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	75	75
Fixed Rate of 5.45%, balloon due March 13, 2039 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	40	40
Interbank Rates Plus 1.500% Expires September 15, 2024 [Member] \| AUD Denominated Tranche [Member] \| Facility B [Member] \| Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	217.6	209.5
Interbank Rates Plus 1.850% Expires September 15, 2024 [Member] \| NZD Denominated Tranche [Member] \| Facility B [Member] \| Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest		6.8
Fixed Rate of 4.49%, Balloon Due January 30, 2040 [Member] \| Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	56	56
Prime or SOFR Plus up to 1.40%, Expires June 7, 2024 [Member] \| Unsecured Multicurrency Credit Agreement [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	60	45
Interbank Rates Plus 0.830% Expires September 15, 2024 [Member] \| AUD Denominated Tranche [Member] \| Facility C and D [Member] \| Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	15.2	2.1
Interbank Rates Plus 0.990% Expires September 15, 2024 [Member] \| NZD Denominated Tranche [Member] \| Facility C and D [Member] \| Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	9.1	10
Interbank Rates Expires September 15, 2023 [Member] \| Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Semi-annual payments of interest	$ 241.9	$ 228.4

Credit and Other Debt Agreeme_4

Credit and Other Debt Agreements - Summary of Corporate and Other Debt (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Premium Financing Debt Facility [Member]
Debt Instrument [Line Items]
Periodic payments of interest and principal, expiry date	Sep. 15, 2024	Sep. 15, 2024
Fixed Rate of 2.40%, Balloon Due November 9, 2031 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	2.40%	2.40%
Periodic payments of interest and principal, expiry date	Nov. 09, 2031	Nov. 09, 2031
Fixed Rate of 3.50%, Balloon Due May 20, 2051 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	3.50%	3.50%
Periodic payments of interest and principal, expiry date	May 20, 2051	May 20, 2051
Fixed Rate of 3.05%, Balloon Due March 9, 2052 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	3.05%	3.05%
Periodic payments of interest and principal, expiry date	Mar. 09, 2052	Mar. 09, 2052
Fixed Rate of 3.69%, Balloon Due June 14, 2022 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	3.69%	3.69%
Periodic payments of interest and principal, expiry date	Jun. 14, 2022	Jun. 14, 2022
Fixed Rate of 5.49%, Balloon Due February 10, 2023 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	5.49%	5.49%
Periodic payments of interest and principal, expiry date	Feb. 10, 2023	Feb. 10, 2023
Fixed Rate of 4.13%, Balloon Due June 24, 2023 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.13%	4.13%
Periodic payments of interest and principal, expiry date	Jun. 24, 2023	Jun. 24, 2023
Fixed Rate of 4.72%, Balloon due February 13, 2024 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.72%	4.72%
Periodic payments of interest and principal, expiry date	Feb. 13, 2024	Feb. 13, 2024
Fixed Rate of 4.58%, Balloon Due February 27, 2024 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.58%	4.58%
Periodic payments of interest and principal, expiry date	Feb. 27, 2024	Feb. 27, 2024
Floating Interest Rate of 1.40% LIBOR Plus Balloon Due June 13, 2024 [Member]
Debt Instrument [Line Items]
Periodic payments of interest and principal, expiry date	Jun. 13, 2024	Jun. 13, 2024
Quarterly payments of interest rate	1.40%	1.40%
Quarterly payments of interest, description	90 day LIBOR plus
Fixed Rate of 4.31%, Balloon Due June 24, 2025 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.31%	4.31%
Periodic payments of interest and principal, expiry date	Jun. 24, 2025	Jun. 24, 2025
Fixed Rate of 4.85%, Balloon due February 13, 2026 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.85%	4.85%
Periodic payments of interest and principal, expiry date	Feb. 13, 2026	Feb. 13, 2026
Fixed Rate of 4.73%, Balloon Due February 27, 2026 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.73%	4.73%
Periodic payments of interest and principal, expiry date	Feb. 27, 2026	Feb. 27, 2026
Fixed Rate of 4.40%, Balloon Due June 2, 2026 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.40%	4.40%
Periodic payments of interest and principal, expiry date	Jun. 02, 2026	Jun. 02, 2026
Fixed Rate of 4.36%, Balloon Due June 24, 2026 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.36%	4.36%
Periodic payments of interest and principal, expiry date	Jun. 24, 2026	Jun. 24, 2026
Fixed Rate of 3.75%, Balloon Due January 30, 2027 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	3.75%	3.75%
Periodic payments of interest and principal, expiry date	Jan. 30, 2027	Jan. 30, 2027
Fixed Rate of 4.09%, Balloon Due June 27, 2027 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.09%	4.09%
Periodic payments of interest and principal, expiry date	Jun. 27, 2027	Jun. 27, 2027
Fixed Rate of 4.09%, Balloon Due August 2, 2027 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.09%	4.09%
Periodic payments of interest and principal, expiry date	Aug. 02, 2027	Aug. 02, 2027
Fixed Rate of 4.14%, Balloon Due August 4, 2027 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.14%	4.14%
Periodic payments of interest and principal, expiry date	Aug. 04, 2027	Aug. 04, 2027
Fixed Rate of 3.46%, Balloon Due December 1, 2027 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	3.46%	3.46%
Periodic payments of interest and principal, expiry date	Dec. 01, 2027	Dec. 01, 2027
Fixed Rate of 4.55%, Balloon Due June 2, 2028 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.55%	4.55%
Periodic payments of interest and principal, expiry date	Jun. 02, 2028	Jun. 02, 2028
Fixed Rate of 4.34%, Balloon due June 13, 2028 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.34%	4.34%
Periodic payments of interest and principal, expiry date	Jun. 13, 2028	Jun. 13, 2028
Fixed Rate of 5.04%, Balloon due February 13, 2029 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	5.04%	5.04%
Periodic payments of interest and principal, expiry date	Feb. 13, 2029	Feb. 13, 2029
Fixed Rate of 4.98%, Balloon Due February 27, 2029 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.98%	4.98%
Periodic payments of interest and principal, expiry date	Feb. 27, 2029	Feb. 27, 2029
Fixed Rate of 4.19%, Balloon Due June 27, 2029 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.19%	4.19%
Periodic payments of interest and principal, expiry date	Jun. 27, 2029	Jun. 27, 2029
Fixed Rate of 4.19%, Balloon Due August 2, 2029 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.19%	4.19%
Periodic payments of interest and principal, expiry date	Aug. 02, 2029	Aug. 02, 2029
Fixed Rate of 3.48%, Balloon Due December 2, 2029 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	3.48%	3.48%
Periodic payments of interest and principal, expiry date	Dec. 02, 2029	Dec. 02, 2029
Fixed Rate of 3.99%, Balloon Due January 30, 2030 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	3.99%	3.99%
Periodic payments of interest and principal, expiry date	Jan. 30, 2030	Jan. 30, 2030
Fixed Rate of 4.44%, Balloon Due June 13, 2030 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.44%	4.44%
Periodic payments of interest and principal, expiry date	Jun. 13, 2030	Jun. 13, 2030
Fixed Rate of 5.14%, Balloon due March 13, 2031 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	5.14%	5.14%
Periodic payments of interest and principal, expiry date	Mar. 13, 2031	Mar. 13, 2031
Fixed Rate of 4.70%, Balloon Due June 2, 2031 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.70%	4.70%
Periodic payments of interest and principal, expiry date	Jun. 02, 2031	Jun. 02, 2031
Fixed Rate of 2.46%, Balloon Due May 5, 2036 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	2.46%	2.46%
Periodic payments of interest and principal, expiry date	May 05, 2036	May 05, 2036
Fixed Rate of 4.09%, Balloon Due January 30, 2032 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.09%	4.09%
Periodic payments of interest and principal, expiry date	Jan. 30, 2032	Jan. 30, 2032
Fixed Rate of 4.34%, Balloon Due June 27, 2032 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.34%	4.34%
Periodic payments of interest and principal, expiry date	Jun. 27, 2032	Jun. 27, 2032
Fixed Rate of 4.34%, Balloon Due August 2, 2032 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.34%	4.34%
Periodic payments of interest and principal, expiry date	Aug. 02, 2032	Aug. 02, 2032
Fixed Rate of 4.59%, Balloon due June 13, 2033 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.59%	4.59%
Periodic payments of interest and principal, expiry date	Jun. 13, 2033	Jun. 13, 2033
Fixed Rate of 5.29%, balloon due March 13, 2034 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	5.29%	5.29%
Periodic payments of interest and principal, expiry date	Mar. 13, 2034	Mar. 13, 2034
Fixed Rate of 4.48%, Balloon Due June 12, 2034 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.48%	4.48%
Periodic payments of interest and principal, expiry date	Jun. 12, 2034	Jun. 12, 2034
Fixed Rate of 4.24%, Balloon Due January 30, 2035 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.24%	4.24%
Periodic payments of interest and principal, expiry date	Jan. 30, 2035	Jan. 30, 2035
Fixed Rate of 2.44%, Balloon Due February 10, 2036 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	2.44%	2.44%
Periodic payments of interest and principal, expiry date	Feb. 10, 2036	Feb. 10, 2036
Fixed Rate of 4.69%, Balloon Due June 13, 2038 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.69%	4.69%
Periodic payments of interest and principal, expiry date	Jun. 13, 2038	Jun. 13, 2038
Fixed Rate of 5.45%, balloon due March 13, 2039 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	5.45%	5.45%
Periodic payments of interest and principal, expiry date	Mar. 13, 2039	Mar. 13, 2039
Fixed Rate of 4.49%, Balloon Due January 30, 2040 [Member]
Debt Instrument [Line Items]
Periodic payment of interest	4.49%	4.49%
Periodic payments of interest and principal, expiry date	Jan. 30, 2040	Jan. 30, 2040
Prime or SOFR Plus up to 1.40%, Expires June 7, 2024 [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Periodic payment of interest	1.40%	1.40%
Periodic payments of interest and principal, expiry date	Jun. 07, 2024	Jun. 07, 2024
Facility B [Member] \| Interbank Rates Plus 1.500% Expires September 15, 2024 [Member] \| Premium Financing Debt Facility [Member] \| AUD Denominated Tranche [Member]
Debt Instrument [Line Items]
Periodic payment of interest	1.50%	1.50%
Facility B [Member] \| Interbank Rates Plus 1.850% Expires September 15, 2024 [Member] \| Premium Financing Debt Facility [Member] \| NZD Denominated Tranche [Member]
Debt Instrument [Line Items]
Periodic payment of interest	1.85%	1.85%
Facility C and D [Member] \| Interbank Rates Plus 0.830% Expires September 15, 2024 [Member] \| Premium Financing Debt Facility [Member] \| AUD Denominated Tranche [Member]
Debt Instrument [Line Items]
Periodic payment of interest	0.83%	0.83%
Facility C and D [Member] \| Interbank Rates Plus 0.990% Expires September 15, 2024 [Member] \| Premium Financing Debt Facility [Member] \| NZD Denominated Tranche [Member]
Debt Instrument [Line Items]
Periodic payment of interest	0.99%	0.99%

Credit and Other Debt Agreeme_5

Credit and Other Debt Agreements - Senior Notes - Additional Information (Detail) - USD ($) $ in Millions			12 Months Ended
	Nov. 09, 2021	May 20, 2021	Dec. 31, 2021	Dec. 31, 2022
Debt Instrument [Line Items]
Loss on extinguishment of debt			$ 16.2
Fixed Rate of 3.50%, Balloon Due May 20, 2051 [Member]
Debt Instrument [Line Items]
Periodic payment of interest			3.50%	3.50%
Fixed Rate of 2.40%, Balloon Due November 9, 2031 [Member]
Debt Instrument [Line Items]
Periodic payment of interest			2.40%	2.40%
Fixed Rate of 3.05%, Balloon Due March 9, 2052 [Member]
Debt Instrument [Line Items]
Periodic payment of interest			3.05%	3.05%
Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold	$ 750	$ 1,500
Weighted average interest rate	2.80%	3.31%
Realized a cash gain (loss) on hedging transaction		$ (57.8)
Derivative instrument, term		10 years
Unsecured Senior Notes [Member] \| Fixed Rate of 2.50%, Balloon Due May 20, 2031 [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 650
Periodic payment of interest		2.50%
Periodic payments of interest and principal, expiry year		2031
Amount payable to redeem the notes, percent of the principal amount following transaction termination event		101%
Number of days to occur reinsurance transaction termination event for note redemption		30 days
Notes redemption date		Aug. 13, 2021
Loss on extinguishment of debt		$ 16.2
Redemption premium		6.5
Unamortized discount amount debt issuance and write-off debt acquisition costs		9.7
Unsecured Senior Notes [Member] \| Fixed Rate of 3.50%, Balloon Due May 20, 2051 [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 850
Periodic payment of interest		3.50%
Periodic payments of interest and principal, expiry year		2051
Unsecured Senior Notes [Member] \| Fixed Rate of 2.40%, Balloon Due November 9, 2031 [Member]
Debt Instrument [Line Items]
Notes issued and sold	$ 400
Periodic payment of interest	2.40%
Periodic payments of interest and principal, expiry year	2031
Unsecured Senior Notes [Member] \| Fixed Rate of 3.05%, Balloon Due March 9, 2052 [Member]
Debt Instrument [Line Items]
Notes issued and sold	$ 350
Periodic payment of interest	3.05%
Periodic payments of interest and principal, expiry year	2052

Credit and Other Debt Agreeme_6

Credit and Other Debt Agreements - Note Purchase Agreements - Additional Information (Detail) - USD ($) $ in Millions				12 Months Ended
	Jun. 14, 2022	May 05, 2021	Feb. 10, 2021	Dec. 31, 2022
Series G note [Member]
Debt Instrument [Line Items]
Operating cash to fund	$ 200
Note Purchase Agreements [Member]
Debt Instrument [Line Items]
Realized a cash gain (loss) on hedging transaction		$ (17.2)	$ (22.9)
Derivative instrument, term		10 years	10 years
Amount payable to redeem the notes, percent of the principal amount				100%
Discount rate used to compute the remaining scheduled payments of principal and interest				U.S. Treasury yield plus 0.5
Note Purchase Agreements [Member] \| Fixed Rate of 5.18%, Balloon Due February 10, 2021 [Member]
Debt Instrument [Line Items]
Repayments of debt			$ 75
Note Purchase Agreements [Member] \| Private Placement [Member] \| Unsecured Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 75	$ 100
Weighted average maturity of notes		15 years	15 years
Weighted average interest rate of notes		3.98%	3.97%
Debt instrument, interest rate		2.46%	2.44%
Debt instrument, due date		2036	2036

Credit and Other Debt Agreeme_7

Credit and Other Debt Agreements - Credit Agreement - Additional Information (Detail) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022 AUD ($)	Dec. 31, 2022 NZD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 AUD ($)	Dec. 31, 2022 NZD ($)	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Liabilities			$ 29,717.6			$ 24,784.9
Long-term debt			16.8
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding			241.9
Interest rate for facility	The interest rates on Facility B are Interbank rates, which vary by tranche, duration and currency, plus a margin of 1.500% and 1.850% for the AU$ and NZ$ tranches, respectively. The interest rates on Facilities C and D are 30 day Interbank rates, plus a margin of 0.830% and 0.990% for the AU$ and NZ$ tranches, respectively. The annual fee for Facility B is 0.675% and 0.8325% for the undrawn commitments for the AU$ and NZ$ tranches, respectively. The annual fee for Facility C is 0.77% and for Facility D is 0.90% of the total commitments of the facilities	The interest rates on Facility B are Interbank rates, which vary by tranche, duration and currency, plus a margin of 1.500% and 1.850% for the AU$ and NZ$ tranches, respectively. The interest rates on Facilities C and D are 30 day Interbank rates, plus a margin of 0.830% and 0.990% for the AU$ and NZ$ tranches, respectively. The annual fee for Facility B is 0.675% and 0.8325% for the undrawn commitments for the AU$ and NZ$ tranches, respectively. The annual fee for Facility C is 0.77% and for Facility D is 0.90% of the total commitments of the facilities
Debt instrument fair value amount			241.9
Revolving Credit Facility [Member] \| Before Amendment [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 340,000,000
Revolving Credit Facility [Member] \| After Amendment [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				410,000,000
Credit Facility Two [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding				325,000,000	$ 0
Line of credit facility, remaining borrowing capacity				25,000,000	25
Net borrowings on premium financing debt facility	$ 350,000,000	$ 25
Credit Facility Three [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding				22,500,000
Net borrowings on premium financing debt facility	$ 60,000,000	$ 10
Annual fee percentage	0.77%	0.77%
Credit Facility Four [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding					14.5
Line of credit facility, remaining borrowing capacity				$ 37,500,000	$ 0.5
Net borrowings on premium financing debt facility		$ 15
Annual fee percentage	0.90%	0.90%
AUD Denominated Tranche [Member] \| Revolving Credit Facility [Member] \| Facility B [Member]
Debt Instrument [Line Items]
Additional margin percentage on interest rate	1.50%	1.50%
Annual fee percentage	0.675%	0.675%
AUD Denominated Tranche [Member] \| Revolving Credit Facility [Member] \| Facility C and D [Member]
Debt Instrument [Line Items]
Additional margin percentage on interest rate	0.83%	0.83%
NZD Denominated Tranche [Member] \| Revolving Credit Facility [Member] \| Facility B [Member]
Debt Instrument [Line Items]
Additional margin percentage on interest rate	1.85%	1.85%
Annual fee percentage	0.8325%	0.8325%
NZD Denominated Tranche [Member] \| Revolving Credit Facility [Member] \| Facility C and D [Member]
Debt Instrument [Line Items]
Additional margin percentage on interest rate	0.99%	0.99%
Note Purchase Agreements [Member] \| Level 3 [Member]
Debt Instrument [Line Items]
Line of credit facility, fair value of amount outstanding			4,942.5
Long-term debt			5,848
Unsecured Multicurrency Credit Agreement [Member]
Debt Instrument [Line Items]
Estimated fair value of outstanding borrowings			60
Unsecured Multicurrency Credit Agreement [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest rates on base rate loans	0%	0%
Fixed rate over SOFR rate, eurocurrency rate or RFR rate	0.825%	0.825%
Annual facility fee of revolving credit facility	0.125%	0.125%
Unsecured Multicurrency Credit Agreement [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest rates on base rate loans	0.40%	0.40%
Fixed rate over SOFR rate, eurocurrency rate or RFR rate	1.40%	1.40%
Annual facility fee of revolving credit facility	0.25%	0.25%
Unsecured Multicurrency Credit Agreement [Member] \| Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			1,150.6
Line of credit facility, amount outstanding			10.6
Liabilities			17.4
Line of credit facility, fair value of amount outstanding			$ 60

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Net EPS (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Net earnings attributable to controlling interests	$ 1,114.2	$ 906.8	$ 818.8
Weighted average number of common shares outstanding	210.3	202.7	191
Dilutive effect of stock options using the treasury stock method	4.4	4.6	4
Weighted average number of common and common equivalent shares outstanding	214.7	207.3	195
Basic net earnings per share	$ 5.30	$ 4.47	$ 4.29
Diluted net earnings per share	$ 5.19	$ 4.37	$ 4.20

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Anti-dilutive stock-based awards shares outstanding	2	1.3	1

Stock Option Plans - Additional

Stock Option Plans - Additional information (Detail) - USD ($) $ / shares in Units, $ in Millions					12 Months Ended
	May 10, 2022	Mar. 15, 2022	Mar. 16, 2021	Mar. 12, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Feb. 01, 2022
Stock Option Plans [Line Items]
Compensation expense related to stock option grants					$ 27.9	$ 17.5	$ 13.6
Total intrinsic value of options exercised					168.2	$ 127.4	$ 106.4
Total unrecognized compensation cost related to nonvested options					$ 94.3
Weighted average period, years					4 years
Black-Scholes Option Pricing Model [Member]
Stock Option Plans [Line Items]
Weighted average fair value per option for all options					$ 33.25	$ 23.38	$ 9.99
Long Term Incentive Plan [Member]
Stock Option Plans [Line Items]
Stock option granted, Share pool	13,500,000
Shares against the pool	3.8
Maximum number of shares available	3,500,000				3,300,000
Number Of Periods Options Expire					7 years
Shares available for grant					13,400,000
Long Term Incentive Plan [Member] \| Officer and Key Employees [Member]
Stock Option Plans [Line Items]
Shares available for grant		1,141,000						1,197,000
Long Term Incentive Plan [Member] \| Maximum [Member]
Stock Option Plans [Line Items]
Minimum exercise price of stock options, percent of fair market value of a share of common stock on the date of grant					100%
2017 Long Term Incentive Plan [Member] \| Officer and Key Employees [Member]
Stock Option Plans [Line Items]
Shares available for grant			1,640,000	1,590,740
Stock options granted, exercise percentage, on the third anniversary date of the grant		34%	34%	34%
Stock options granted, exercise percentage, on the fourth anniversary date of the grant		33%	33%	33%
Stock options granted, exercise percentage, on the fifth anniversary date of the grant		33%	33%	33%
2017 Long Term Incentive Plan [Member] \| Maximum [Member]
Stock Option Plans [Line Items]
Maximum period for the exercise of stock options, years					7 years	7 years	7 years
2017 Long Term Incentive Plan [Member] \| Minimum [Member]
Stock Option Plans [Line Items]
Period of service from grant date stock options awarded not subject to forfeiture					2 years	2 years	2 years
2017 Long Term Incentive Plan [Member] \| Minimum [Member] \| Executive Officer [Member]
Stock Option Plans [Line Items]
Minimum age of employee with not subject to award forfeiture on condition compliance					55 years	55 years	55 years

Stock Option Plans - Black-Scho

Stock Option Plans - Black-Scholes Option Pricing Model with Weighted Average (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Payment Arrangement [Abstract]
Expected dividend yield	1.30%	1.50%	2.10%
Expected risk-free interest rate	1.90%	0.90%	0.70%
Volatility	23.10%	22.90%	17.30%
Expected life (in years)	5 years 4 months 24 days	5 years 4 months 24 days	5 years 4 months 24 days

Stock Option Plans - Stock Opti

Stock Option Plans - Stock Option Activity and Related Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Shares Under Option, Beginning balance	7.5	7.5
Shares Under Option, Granted	2.4	1.6
Shares Under Option, Exercised	(1.4)	(1.4)
Shares Under Option, Forfeited or canceled	(0.2)	(0.2)
Shares Under Option, Ending balance	8.3	7.5
Shares Under Option, Exercisable at end of year	1.8	2.1
Shares Under Option, Ending unvested and expected to vest	5.9	5.1
Weighted Average Exercise Price, Beginning balance	$ 81.30	$ 65.09
Weighted Average Exercise Price, Granted	157.74	127.90
Weighted Average Exercise Price, Exercised	53.53	49.10
Weighted Average Exercise Price, Forfeited or canceled	109.10	88.84
Weighted Average Exercise Price, Ending balance	107.47	81.30
Weighted Average Exercise Price, Exercisable at end of year	61.11	51.46
Weighted Average Exercise Price, Ending unvested and expected to vest	$ 118.80	$ 91.56
Weighted Average Remaining Contractual Term (in years), Ending balance	4 years 2 months 4 days	3 years 10 months 24 days
Weighted Average Remaining Contractual Term (in years), Exercisable at end of year	1 year 6 months 21 days	1 year 6 months 25 days
Weighted Average Remaining Contractual Term (in years), Ending unvested and expected to vest	4 years 10 months 9 days	4 years 8 months 19 days
Aggregate Intrinsic Value, Ending Balance	$ 668.9	$ 666.3
Aggregate Intrinsic Value, Exercisable at end of year	230.8	242.3
Aggregate Intrinsic Value, Ending unvested and expected to vest	$ 413.2	$ 401.7

Stock Option Plans - Stock Op_2

Stock Option Plans - Stock Options Outstanding and Exercisable (Detail) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 43.71
Range of Exercise Prices, maximum	$ 161.14
Option Outstanding, Number Outstanding	8.3
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	4 years 2 months 4 days	3 years 10 months 24 days
Option Outstanding, Weighted Average Exercise Price	$ 107.47	$ 81.30	$ 65.09
Options Exercisable, Number Exercisable	1.8
Option Exercisable, Weighted Average Exercise Price	$ 61.11
Exercise Prices Range $ 43.71 - $ 43.71 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	43.71
Range of Exercise Prices, maximum	$ 43.71
Option Outstanding, Number Outstanding	0.4
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	2 months 15 days
Option Outstanding, Weighted Average Exercise Price	$ 43.71
Options Exercisable, Number Exercisable	0.4
Option Exercisable, Weighted Average Exercise Price	$ 43.71
Exercise Prices Range $ 49.55 - $ 56.86 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	49.55
Range of Exercise Prices, maximum	$ 56.86
Option Outstanding, Number Outstanding	0.7
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	1 year 2 months 15 days
Option Outstanding, Weighted Average Exercise Price	$ 56.84
Options Exercisable, Number Exercisable	0.7
Option Exercisable, Weighted Average Exercise Price	$ 56.85
Exercise Prices Range $ 70.74 - $ 70.74 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	70.74
Range of Exercise Prices, maximum	$ 70.74
Option Outstanding, Number Outstanding	0.8
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	2 years 2 months 15 days
Option Outstanding, Weighted Average Exercise Price	$ 70.74
Options Exercisable, Number Exercisable	0.4
Option Exercisable, Weighted Average Exercise Price	$ 70.74
Exercise Prices Range $ 79.59 - $ 79.59 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	79.59
Range of Exercise Prices, maximum	$ 79.59
Option Outstanding, Number Outstanding	1
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	3 years 2 months 12 days
Option Outstanding, Weighted Average Exercise Price	$ 79.59
Options Exercisable, Number Exercisable	0.3
Option Exercisable, Weighted Average Exercise Price	$ 79.59
Exercise Prices Range $ 86.17 - $ 86.17 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	86.17
Range of Exercise Prices, maximum	$ 86.17
Option Outstanding, Number Outstanding	1.5
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	4 years 2 months 12 days
Option Outstanding, Weighted Average Exercise Price	$ 86.17
Option Exercisable, Weighted Average Exercise Price	86.17
Exercise Prices Range $ 127.90 - $ 127.90 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	127.90
Range of Exercise Prices, maximum	$ 127.90
Option Outstanding, Number Outstanding	1.5
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	5 years 2 months 15 days
Option Outstanding, Weighted Average Exercise Price	$ 127.90
Exercise Prices Range $ 156.85 - $ 156.85 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	156.85
Range of Exercise Prices, maximum	$ 156.85
Option Outstanding, Number Outstanding	1.2
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 1 month 2 days
Option Outstanding, Weighted Average Exercise Price	$ 156.85
Exercise Prices Range $ 158.56 - $ 161.14 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	158.56
Range of Exercise Prices, maximum	$ 161.14
Option Outstanding, Number Outstanding	1.2
Option Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 2 months 15 days
Option Outstanding, Weighted Average Exercise Price	$ 158.65

Deferred Compensation - Additio

Deferred Compensation - Additional Information (Detail) - USD ($) shares in Millions	3 Months Ended			12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investments And Employee Deferred Compensation Plan [Line Items]
Deferred Equity Participation Plan, distributions to key executives, age				age 62 (or the one-year anniversary of the date of the grant for participants over the age of 61 as of the grant date) or upon or after their actual retirement if later.
Deferred Equity Participation Sub-plans, distributions requisite service description				we annually make awards under sub-plans of the DEPP for certain production staff, which generally provide for vesting and/or distributions no sooner than five years from the date of awards, although certain awards vest and/or distribute after the earlier of fifteen years or the participant reaching age 65.
Deferred Equity Participation Sub-plans, distributions to key executives, age				age 65
Deferred Equity Participation Plan (DEPP) [Member]
Investments And Employee Deferred Compensation Plan [Line Items]
Awards approved by committee, value	$ 26,300,000	$ 17,000,000	$ 14,100,000
Charge to compensation expenses related to awards				$ 18,500,000	$ 14,100,000	$ 12,200,000
Unearned deferred compensation, value				$ 77,700,000	$ 67,400,000
Unearned deferred compensation, shares				2.5	2.7
Total intrinsic value of unvested equity based awards				$ 478,700,000	$ 451,000,000
Cash and equity awards with aggregate fair value vested and distributed to participants				45,600,000	19,100,000	41,200,000
Deferred Equity Participation Plan Sub Plans [Member]
Investments And Employee Deferred Compensation Plan [Line Items]
Awards approved by committee, value				1,900,000	3,200,000	1,800,000
Charge to compensation expenses related to awards				2,300,000	2,300,000	1,900,000
Distributions from the sub-plans				0	0
Deferred Cash Participation Plan (DCPP) [Member]
Investments And Employee Deferred Compensation Plan [Line Items]
Awards approved by committee, value	$ 8,300,000	$ 7,200,000	$ 3,000,000
Charge to compensation expenses related to awards				13,400,000	9,600,000	6,900,000
Cash and equity awards with aggregate fair value vested and distributed to participants				$ 16,900,000	$ 6,700,000	$ 3,200,000

Restricted Stock, Performance_3

Restricted Stock, Performance Share and Cash Awards - Additional Information (Detail)

3 Months Ended

12 Months Ended

May 10, 2022 shares

Mar. 15, 2022 USD ($) shares

Mar. 16, 2021 USD ($) shares

Mar. 12, 2020 USD ($) shares

Mar. 31, 2023 shares

Mar. 31, 2022 shares

Mar. 31, 2021 shares

Mar. 31, 2020 shares

Dec. 31, 2022 USD ($) TIME shares

Dec. 31, 2021 USD ($) shares

Dec. 31, 2020 USD ($) shares

Dec. 31, 2019 USD ($)

Dec. 31, 2018 USD ($)

Mar. 31, 2019 shares

Mar. 14, 2019 USD ($) shares

Mar. 15, 2018 USD ($) shares

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Share-based compensation, shares outstanding | shares

8,300,000

7,500,000

Officer and Key Employees [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Performance awards period, years

1 year

Restricted Stock Units (RSUs) [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Shares granted in the period | shares

641,000

314,000

405,870

650,355

326,584

422,610

Fair value of grants in period

$ 99,400,000

$ 40,100,000

$ 34,900,000

Share based payment award vesting date

Mar. 15, 2027

Mar. 16, 2026

Mar. 12, 2025

Period of service from grant date stock options awarded not subject to forfeiture

2 years

Restricted stock or unit expense

36,400,000

26,700,000

23,000,000

Restricted Stock Units (RSUs) [Member] | Executive Officer [Member] | Minimum [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Minimum age of employee with not subject to award forfeiture on condition compliance

55 years

Unvested Restricted Stock [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Total intrinsic value

401,300,000

331,800,000

Equity awards with an aggregate fair value

62,000,000

48,900,000

Performance Shares [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Restricted stock or unit expense

15,200,000

15,900,000

16,200,000

Total intrinsic value

62,700,000

64,300,000

Equity awards with an aggregate fair value

$ 21,800,000

$ 19,100,000

12,500,000

Shares authorized | shares

54,000

67,000

82,500

Performance share awards approved, Fair value

$ 8,600,000

$ 7,100,000

Vesting period, years

2 years

2017 Performance Share Awards [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Provisional awards, terms

The 2022, 2021 and 2020 awards are subject to a three-year performance period that begins on January 1, 2022, 2021 and 2020, respectively, and vest on the three-year anniversary of the date of grant (March 15, 2025, March 16, 2024 and March 12, 2023).

Cash Awards [Member] | Scenario, Forecast [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Provisional compensation cash award approved for future grant by compensation committee, units | shares

122,000

Performance awards expiration date

Jan. 01, 2025

Cash Awards [Member] | Officer and Key Employees [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Provisional awards, terms

The ultimate award value will be equal to the trailing twelve‑month price of our common stock on December 31, 2024, multiplied by the number of units subject to the award, but limited to between 0.5 and 1.5 times the original value of the units determined as of the grant date.

Provisional compensation cash awards approved for future grant by compensation committee, value

$ 19,900,000

$ 18,800,000

$ 18,400,000

$ 16,500,000

Provisional compensation cash award approved for future grant by compensation committee, units | shares

125,000

147,000

213,000

143,000

208,000

200,000

206,800

Ultimate award value, multiples of original value of the units, minimum | TIME

0.5

Ultimate award value, multiples of original value of the units, maximum | TIME

1.5

Cash-based compensation awards, expenses

$ 0

2021 Provisional Cash Awards [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Cash-based compensation awards, expenses

$ 12,400,000

$ 0

Performance awards expiration date

Jan. 01, 2024

2020 Provisional Cash Awards [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Cash-based compensation awards, expenses

$ 12,100,000

12,600,000

Performance awards expiration date

Jan. 01, 2023

2019 Provisional Cash Awards [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Provisional compensation cash award approved for future grant by compensation committee, units | shares

177,000

Cash-based compensation awards, expenses

$ 21,100,000

$ 11,500,000

10,600,000

$ 0

Performance awards expiration date

Jan. 01, 2022

2019 Provisional Cash Awards [Member] | Officer and Key Employees [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Provisional compensation cash awards approved for future grant by compensation committee, value

$ 15,000,000

Provisional compensation cash award approved for future grant by compensation committee, units | shares

190,000

219,000

2018 Provisional Cash Awards [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Provisional compensation cash award approved for future grant by compensation committee, units | shares

176,300

Cash-based compensation awards, expenses

$ 17,700,000

$ 9,900,000

$ 8,900,000

$ 0

Performance awards expiration date

Jan. 01, 2021

2017 Provisional Cash Awards [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Provisional compensation cash award approved for future grant by compensation committee, units | shares

221,600

Cash-based compensation awards, expenses

$ 18,900,000

Long Term Incentive Plan [Member]

Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]

Share-based compensation, shares outstanding, Value

$ 4,000,000

Shares granted in the period | shares

3,500,000

3,300,000

Restricted Stock, Performance_4

Restricted Stock, Performance Share and Cash Awards - Schedule of Restricted Stock Awards Vesting Periods (Detail) - Restricted Stock Units Granted [Member] - shares	3 Months Ended			12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Vesting Period [Line Items]
Shares granted in the period	641,000	314,000	405,870	650,355	326,584	422,610
Vesting Period One Year [Member]
Vesting Period [Line Items]
Shares granted in the period				9,270	10,105	16,740
Vesting period, years				1 year
Vesting Period Two Years [Member]
Vesting Period [Line Items]
Shares granted in the period				0	2,105	8,870
Vesting period, years				2 years
Vesting Period Five Years [Member]
Vesting Period [Line Items]
Shares granted in the period				641,085	314,374	397,000
Vesting period, years				5 years

Retirement Plans - Reconciliati

Retirement Plans - Reconciliation of Balances of Pension Benefit Obligation and Fair Value of Plan Assets (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Change in pension benefit obligation:
Benefit obligation at beginning of year	$ 279,400,000	$ 290,600,000
Service cost	500,000	500,000	$ 800,000
Interest cost	$ 6,800,000	$ 6,400,000	$ 8,000,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Labor and Related Expense	Labor and Related Expense	Labor and Related Expense
Net actuarial gain	$ (58,700,000)	$ (2,800,000)
Benefits paid	(16,100,000)	(15,300,000)
Benefit obligation at end of year	211,900,000	279,400,000	$ 290,600,000
Change in plan assets:
Fair value of plan assets at beginning of year	282,300,000	262,800,000
Actual (loss) return on plan assets	(53,700,000)	34,800,000
Contributions by the company	0	0	0
Benefits paid	(16,100,000)	(15,300,000)
Fair value of plan assets at end of year	212,500,000	282,300,000	$ 262,800,000
Funded status of the plan (underfunded)	600,000	2,900,000
Amounts recognized in the consolidated balance sheet consist of:
Noncurrent assets - accrued benefit liability	600,000	2,900,000
Accumulated other comprehensive income	54,200,000	42,500,000
Net amount included in retained earnings	$ 54,800,000	$ 45,400,000

Retirement Plans - Components o

Retirement Plans - Components of Net Periodic Pension Benefit Cost and Other Changes in Plan Assets and Obligations Recognized in Earnings and Other Comprehensive Earnings (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net periodic pension cost:
Service cost	$ 0.5	$ 0.5	$ 0.8
Interest cost on benefit obligation	6.8	6.4	8
Expected return on plan assets	$ (19.1)	$ (17.7)	$ (16.4)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Labor and Related Expense	Labor and Related Expense	Labor and Related Expense
Amortization of net loss	$ 2.4	$ 5.9	$ 6.2
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Labor and Related Expense	Labor and Related Expense	Labor and Related Expense
Net periodic benefit income	$ (9.4)	$ (4.9)	$ (1.4)
Other changes in plan assets and obligations recognized in other comprehensive earnings:
Net loss (gain) incurred	14.1	(19.9)	4.7
Amortization of net loss	(2.4)	(5.9)	(6.2)
Total recognized in other comprehensive income (loss)	11.7	(25.8)	(1.5)
Total recognized in net periodic pension cost and other comprehensive income (loss)	$ 2.3	$ (30.7)	$ (2.9)

Retirement Plans - Weighted Ave

Retirement Plans - Weighted Average Assumptions of Pension Benefit Obligation and Net Periodic Pension Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate, pension benefit obligation	5.25%	2.50%
Weighted average expected long-term rate of return on plan assets, pension benefit obligation	7%	7%
Discount rate, net periodic pension benefit cost	2.50%	2.25%	3%
Weighted average expected long-term rate of return on plan assets, net periodic pension benefit cost	7%	7%	7%

Retirement Plans - Schedule of

Retirement Plans - Schedule of Benefit Payments Expected to be Paid by Plan (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2023	$ 17.1
2024	17.1
2025	17.3
2026	17.3
2027	17.3
2028 to 2032	$ 81.9

Retirement Plans - Summary of P

Retirement Plans - Summary of Plan's Weighted Average Asset Allocations (Detail)	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	100%	100%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	62%	60%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	31%	32%
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	7%	8%

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Expected period of return on plan assets, years	10 years	10 years
Minimum contribution by employer	$ 0	$ 0	$ 0
Discretionary contributions by employer	0	0	0
Fair value of plan assets	$ 212,500,000	282,300,000	262,800,000
Foreign Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Matching contributions by employer, percentage	100%
Percentage of employer matching contributions on eligible compensation	5%
Contribution expense to plan	$ 62,900,000	$ 51,800,000	44,300,000
Additional percentage of eligible compensation for matching contributions by employer	5%
Qualified Contributory Savings and Thrift 401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Matching contributions by employer, percentage	100%
Percentage of employer matching contributions on eligible compensation	5%	5%
Matching contributions vesting schedule	5 years
Contribution expense to plan	$ 73,800,000	$ 65,700,000	63,600,000
Nonqualified Deferred Compensation Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of employer matching contributions on eligible compensation	5%
Contribution expense to plan	$ 11,000,000	8,700,000	$ 7,800,000
Fair value of plan assets	$ 578,200,000	$ 606,600,000

Retirement Plans - Summary of_2

Retirement Plans - Summary of Plan's Assets Carried at Fair Value (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Total fair value	$ 212.5	$ 282.3	$ 262.8
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value	112.9	158.1
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value	$ 99.6	$ 124.2	$ 121

Retirement Plans - Reconcilia_2

Retirement Plans - Reconciliation of Beginning and Ending Balances for Level 3 Assets of Plan Measured at Fair Value (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 282.3	$ 262.8
Fair value of plan assets at end of year	212.5	282.3
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	124.2	121
Settlements	(1.5)	(15.2)
Unrealized gain	(23.1)	18.4
Fair value of plan assets at end of year	$ 99.6	$ 124.2

Investments - Additional Inform

Investments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Total assets of variable interest entities	$ 38,907.8	$ 33,345	$ 22,331.4
Total liabilities of variable interest entities	$ 29,717.6	24,784.9
Ownership interest held	50%
Variable Interest Entity, Not Primary Beneficiary [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest held	12%
Chem-Mod Clean-Coal Venture [Member] \| VIE [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of variable interest entities	$ 14.8	19.4
Total liabilities of variable interest entities	1.1	1.1
Chem-Mod Clean-Coal Venture - U.S. and Canadian Operations [Member]
Schedule of Equity Method Investments [Line Items]
Total revenues of limited liability companies	1	82.7
Total expenses of limited liability companies	$ 5.7	$ 14.5
Chem-Mod International LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest held	31.50%
Chem Mod L L C [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest held	46.50%

Investments - Clean Coal Invest

Investments - Clean Coal Investments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2022 USD ($) Entities Plant	Dec. 31, 2021 USD ($)
Chem-Mod LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of clean coal production plants owned \| Plant	35
Chem-Mod LLC [Member] \| 2009 Era Plants [Member]
Schedule of Equity Method Investments [Line Items]
Number of clean coal production plants owned \| Plant	14
Chem-Mod LLC [Member] \| 2011 Era Plants [Member]
Schedule of Equity Method Investments [Line Items]
Number of clean coal production plants owned \| Plant	21
Clean-Coal Investments [Member]
Schedule of Equity Method Investments [Line Items]
Number of variable interest entities \| Entities	1
Clean-Coal Investments [Member] \| VIE [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of limited liability companies	$ 35,300,000
Total liability of limited liability companies	$ 35,300,000
Total revenues of limited liability companies		$ 0
Total expenses of limited liability companies		$ 300,000

Investments - Other Investments

Investments - Other Investments - Additional Information (Detail)	Dec. 31, 2022 USD ($) Investment Venture	Dec. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Non controlling interest certified low-income housing developments \| Investment	5
Liabilities	$ 29,717,600,000	$ 24,784,900,000
Variable Interest Entity, Not Primary Beneficiary [Member] \| Venture Capital Funds [Member]
Schedule of Equity Method Investments [Line Items]
Liabilities	$ 400,000
Other Investments [Member] \| One Startup Venture [Member]
Schedule of Equity Method Investments [Line Items]
Non-controlling interest in startup venture number \| Venture	1
Assets	$ 2,200,000
Other Investments [Member] \| Four Venture Capital Funds [Member]
Schedule of Equity Method Investments [Line Items]
Assets	$ 3,400,000
Non controlling interest in venture capital funds number \| Venture	4
Other Investments [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Schedule of Equity Method Investments [Line Items]
Assets	$ 4,600,000
Other Investments [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member] \| Five Certified Low-income Housing Developments [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value of investments	$ 0

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Detail) $ in Millions	12 Months Ended
Leases - Components of Lease Expense (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Total net lease expense	$ 160.4
Operating [Member]
Operating lease expense	139.9
Variable lease expense	21.7
Investment Income [Member]
Sublease income	$ (1.2)

Leases - Summary of Supplementa

Leases - Summary of Supplemental Cash Flow Information Related to Leases (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 121.4
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 102.9

Leases - Summary of Supplemen_2

Leases - Summary of Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Lease right-of-use assets	$ 346.7	$ 358.6
Other current lease liabilities	$ 82.4
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued compensation and other accrued liabilities
Lease liabilities	$ 300.4	$ 309.3
Total lease liabilities	$ 382.8
Weighted-average remaining lease term, years	5 years 4 months 24 days
Weighted-average discount rate	3.30%

Leases - Maturities of Operatin

Leases - Maturities of Operating Lease Liabilities (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Leases [Abstract]
2023	$ 98.6
2024	84.2
2025	67.7
2026	54.3
2027	41.7
Thereafter	72.6
Total lease payments	419.1
Less interest	(36.3)
Total	$ 382.8

Leases - Additional Information

Leases - Additional Information (Detail) $ in Millions	12 Months Ended
Leases - Additional Information (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Lessee, operating lease, option to extend	20.0 years
Operating lease liability not yet commenced	$ 22.4
Minimum [Member]
Operating lease, remaining lease term	1 month 6 days
Lessee, operating lease, lease not yet commenced, term of contract	6 months
Maximum [Member]
Operating lease, remaining lease term	14 years
Lessee, operating lease, lease not yet commenced, term of contract	10 years

Derivatives and Hedging Activ_3

Derivatives and Hedging Activity - Summary of Notional and Fair Values of Derivative Instruments (Detail) - USD ($)		Dec. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Notional Amount		$ 1,063,000,000	$ 1,017,300,000
Derivative Assets		128,400,000	16,800,000
Derivative Liabilities		45,500,000	21,300,000
Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional Amount		950,000,000	1,000,000,000
Interest Rate Contracts [Member] \| Other current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets		56,500,000	4,800,000
Interest Rate Contracts [Member] \| Other noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets		56,600,000	3,400,000
Interest Rate Contracts [Member] \| Accrued compensation and other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities			1,300,000
Interest Rate Contracts [Member] \| Other noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities			11,500,000
Foreign Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	[1]	113,000,000	17,300,000
Derivative Assets	[1]	14,500,000
Foreign Exchange Contracts [Member] \| Other current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	[1]	800,000	4,300,000
Foreign Exchange Contracts [Member] \| Other noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	[1]		4,300,000
Foreign Exchange Contracts [Member] \| Accrued compensation and other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	[1]	18,500,000	1,300,000
Foreign Exchange Contracts [Member] \| Other noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	[1]	$ 27,000,000	$ 7,200,000

[1] Included within foreign exchange contracts at December 31, 2022 were $ 948.8 million of call options offset with $ 948.8 million of put options, and $ 12.4 million of buy forwards offset with $ 125.4 million of sell forwards. Included within foreign exchange contracts at December 31, 2021 were $ 483.8 million of call options offset with $ 483.8 million of put options, and $ 10.5 million of buy forwards offset with $ 27.9 million of sell forwards.

Derivatives and Hedging Activ_4

Derivatives and Hedging Activity - Summary of Notional and Fair Values of Derivative Instruments (Parenthetical) (Detail) - Foreign Exchange Contracts [Member] - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Call Options [Member]
Derivatives, Fair Value [Line Items]
Foreign exchange derivative contracts	$ 948.8	$ 483.8
Put Options [Member]
Derivatives, Fair Value [Line Items]
Foreign exchange derivative contracts	948.8	483.8
Forward Contracts [Member] \| Call Options [Member]
Derivatives, Fair Value [Line Items]
Foreign exchange derivative contracts	125.4	27.9
Forward Contracts [Member] \| Put Options [Member]
Derivatives, Fair Value [Line Items]
Foreign exchange derivative contracts	$ 12.4	$ 10.5

Derivatives and Hedging Activ_5

Derivatives and Hedging Activity - Summary of Amounts of Derivative Gains (Losses) Recognized In Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Loss	[1]	$ 152.5	$ 22.3
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Earnings		3.2	(5.8)
Amount of Gain (Loss) Recognized in Earnings Related to Amount Excluded from Effectiveness Testing		3.2	1.7
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Earnings		$ (1.2)	$ (1.1)
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]		Interest	Interest
Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Earnings		$ 6.3	$ (3.3)
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]		Total revenues	Total revenues
Interest expense [Member] \| Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Loss	[1]	$ 179.3	$ 35.8
Commission revenue [Member] \| Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Loss	[1]	(26.8)	(13.5)
Amount of Gain (Loss) Recognized in Earnings Related to Amount Excluded from Effectiveness Testing		(0.1)
Compensation expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Earnings		$ (1.1)	$ (0.8)
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]		Compensation	Compensation
Amount of Gain (Loss) Recognized in Earnings Related to Amount Excluded from Effectiveness Testing		$ 1.9	$ 1
Operating expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Earnings		$ (0.8)	$ (0.6)
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]		Operating	Operating
Amount of Gain (Loss) Recognized in Earnings Related to Amount Excluded from Effectiveness Testing		$ 1.4	$ 0.7

[1] During 2022, the amount excluded from the assessment of hedge effectiveness for our foreign exchange contracts recognized in accumulated other comprehensive loss was a gain of $ 0.9 million.

Derivatives and Hedging Activ_6

Derivatives and Hedging Activity - Summary of Amounts of Derivative Gains (Losses) Recognized In Accumulated Other Comprehensive Loss (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Other comprehensive income (loss), foreign currency transaction and translation adjustment, net of tax	$ (512)	$ (121)	$ 184.1
Foreign Exchange [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other comprehensive income (loss), foreign currency transaction and translation adjustment, net of tax	$ 0.9

Derivatives and Hedging Activ_7

Derivatives and Hedging Activity - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Estimated pretax loss to be reclassified from accumulated other comprehensive income into earnings	$ 29.4

Commitments, Contingencies an_3

Commitments, Contingencies and Off-Balance Sheet Arrangements - Contractual Obligations (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Senior Notes [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, Thereafter	$ 1,600
Contractual Obligations, Payments Due by Period, Total	1,600
Note Purchase Agreements [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2023	250
Contractual Obligations, Payments Due by Period, 2024	475
Contractual Obligations, Payments Due by Period, 2025	200
Contractual Obligations, Payments Due by Period, 2026	640
Contractual Obligations, Payments Due by Period, 2027	478
Contractual Obligations, Payments Due by Period, Thereafter	2,205
Contractual Obligations, Payments Due by Period, Total	4,248
Credit Agreement [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2023	60
Contractual Obligations, Payments Due by Period, Total	60
Premium Financing Debt Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2023	241.9
Contractual Obligations, Payments Due by Period, Total	241.9
Interest On Debt [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2023	229
Contractual Obligations, Payments Due by Period, 2024	212.3
Contractual Obligations, Payments Due by Period, 2025	197.7
Contractual Obligations, Payments Due by Period, 2026	178.8
Contractual Obligations, Payments Due by Period, 2027	160.4
Contractual Obligations, Payments Due by Period, Thereafter	1,408.1
Contractual Obligations, Payments Due by Period, Total	2,386.3
Total Debt Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2023	780.9
Contractual Obligations, Payments Due by Period, 2024	687.3
Contractual Obligations, Payments Due by Period, 2025	397.7
Contractual Obligations, Payments Due by Period, 2026	818.8
Contractual Obligations, Payments Due by Period, 2027	638.4
Contractual Obligations, Payments Due by Period, Thereafter	5,213.1
Contractual Obligations, Payments Due by Period, Total	8,536.2
Operating Lease Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2023	98.6
Contractual Obligations, Payments Due by Period, 2024	84.2
Contractual Obligations, Payments Due by Period, 2025	67.7
Contractual Obligations, Payments Due by Period, 2026	54.3
Contractual Obligations, Payments Due by Period, 2027	41.7
Contractual Obligations, Payments Due by Period, Thereafter	72.6
Contractual Obligations, Payments Due by Period, Total	419.1
Less Sublease Arrangements [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Receivable by Period, 2023	(0.9)
Contractual Obligations, Payments Receivable by Period, 2024	(0.6)
Contractual Obligations, Payments Receivable by Period, 2025	(0.3)
Contractual Obligations, Payments Receivable by Period, 2026	(0.3)
Contractual Obligations, Payments Receivable by Period, 2027	(0.2)
Contractual Obligations, Payments Receivable by Period, Total	(2.3)
Outstanding Purchase Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2023	117.4
Contractual Obligations, Payments Due by Period, 2024	86.8
Contractual Obligations, Payments Due by Period, 2025	36.1
Contractual Obligations, Payments Due by Period, 2026	16.8
Contractual Obligations, Payments Due by Period, 2027	12.3
Contractual Obligations, Payments Due by Period, Thereafter	14.6
Contractual Obligations, Payments Due by Period, Total	284
Total Contractual Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2023	996
Contractual Obligations, Payments Due by Period, 2024	857.7
Contractual Obligations, Payments Due by Period, 2025	501.2
Contractual Obligations, Payments Due by Period, 2026	889.6
Contractual Obligations, Payments Due by Period, 2027	692.2
Contractual Obligations, Payments Due by Period, Thereafter	5,300.3
Contractual Obligations, Payments Due by Period, Total	$ 9,237

Commitments, Contingencies an_4

Commitments, Contingencies and Off-Balance Sheet Arrangements - Additional Information (Detail)		12 Months Ended
	Dec. 20, 2022 USD ($)	Dec. 31, 2022 USD ($) ft² LetterOfCredit Employee	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of square feet \| ft²		360,000
Number of employees will accommodate at new facility \| Employee		2,000
Total rent expense		$ 176,600,000	$ 153,400,000	$ 154,000,000
Aggregate amount of maximum earnout obligations related to acquisitions		1,946,200,000	1,873,900,000
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet		1,077,300,000	988,500,000
Aggregate amount of earnout obligation expected settlement in cash or stock at option		734,000,000	670,300,000
Aggregate amount of earnout obligation expected settlement in cash		343,300,000	$ 318,200,000
Debt		16,800,000
Liabilities recorded on self-insurance		17,400,000
Income tax credits and adjustments		$ 108,000,000
Security Deposit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued \| LetterOfCredit		2
Collateral [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued \| LetterOfCredit		1
Self-Insurance Deductibles [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued \| LetterOfCredit		2
Rent-A-Captive Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Number of letters of credit issued \| LetterOfCredit		7
Errors And Omissions [Member] \| Up to $4.5 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claims, amount retained		$ 2,000,000
Errors And Omissions [Member] \| Up to $10 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claims, amount retained		15,000,000
Insurance claim arise during ordinary course of business		15,000,000
Errors And Omissions [Member] \| Up to $20.0 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claims, amount retained		0
Errors And Omissions [Member] \| Up to $27.0 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claims, amount retained		0
Letter of Credit [Member] \| Security Deposit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt		500,000
Letter of Credit [Member] \| Collateral [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt		800,000
Letter of Credit [Member] \| Self-Insurance Deductibles [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt		9,200,000
Liabilities recorded on self-insurance		17,400,000
Letter of Credit [Member] \| Rent-A-Captive Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Debt		2,500,000
BCHR Holdings, L.P [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Initial gross consideration	$ 660,000,000
Net of agreed seller funded expenses and net working capital	$ 585,000,000
Minimum [Member] \| Errors And Omissions [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Actuarial range value		10,000,000
Minimum [Member] \| Errors And Omissions [Member] \| Up to $4.5 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claim arise during ordinary course of business		15,000,000
Minimum [Member] \| Errors And Omissions [Member] \| Up to $20.0 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claim arise during ordinary course of business		100,000,000
Minimum [Member] \| Errors And Omissions [Member] \| Up to $27.0 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claim arise during ordinary course of business		$ 225,000,000
Minimum [Member] \| Unconsolidated Investments in Enterprises [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Ownership interest		1%
Maximum [Member] \| Errors And Omissions [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Actuarial range value		$ 1,800,000
Maximum [Member] \| Errors And Omissions [Member] \| Up to $4.5 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claim arise during ordinary course of business		100,000,000
Maximum [Member] \| Errors And Omissions [Member] \| Up to $20.0 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claim arise during ordinary course of business		225,000,000
Maximum [Member] \| Errors And Omissions [Member] \| Up to $27.0 Million [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Insurance claim arise during ordinary course of business		$ 0
Maximum [Member] \| Unconsolidated Investments in Enterprises [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Ownership interest		50%
Tax Increment Financing [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credits receivable period		15 years
Economic development for growing economy tax credit		$ 41,400,000
Tax Increment Financing [Member] \| Minimum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credit expect to receive		50,000,000
Tax Increment Financing [Member] \| Maximum [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Property tax credit expect to receive		$ 80,000,000

Commitments, Contingencies an_5

Commitments, Contingencies and Off-Balance Sheet Arrangements - Off-Balance Sheet Commitments (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - 2023	$ 1.4
Amount of Commitment Expiration by Period - 2024	2
Amount of Commitment Expiration by Period - 2025	0.2
Amount of Commitment Expiration by Period - 2026	0.1
Amount of Commitment Expiration by Period - 2027	0.1
Amount of Commitment Expiration by Period - Thereafter	13
Total Amounts Committed	16.8
Financial Guarantees [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - 2023	1.4
Amount of Commitment Expiration by Period - 2024	2
Amount of Commitment Expiration by Period - 2025	0.2
Amount of Commitment Expiration by Period - 2026	0.1
Amount of Commitment Expiration by Period - 2027	0.1
Total Amounts Committed	3.8
Letters of Credit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - Thereafter	13
Total Amounts Committed	$ 13

Commitments, Contingencies an_6

Commitments, Contingencies and Off-Balance Sheet Arrangements - Outstanding Letters of Credit, Financial Guarantees and Funding Commitments (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Maximum Exposure	$ 16.8
Liability Recorded	$ 17.4
Funding Commitment to an Equity Investment - to be Funded in 2023 [Member] \| Other Investments [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Credit Support Under Letters of Credit for Deductibles Due by Us on Our Own Insurance Coverage's Expires After 2026 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 9.2
Liability Recorded	$ 17.4
Credit Enhancement Under Letters of Credit for Our Captive Insurance Operations to Meet Minimum Statutory Capital Requirement's Expires After 2026 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	Reimbursement of LOC fees
Maximum Exposure	$ 2.5
Collateral Related to Claims Funds Held in a Fiduciary Capacity by a Recent Acquisition Expires 2023 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 0.8
Credit Support under Letters of Credit in lieu of Security Deposits for two Leases from Acquisitions - Expires after 2023 and 2026 [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 0.5
Financial Guarantees of Loans to Five Canadian Based Employees Trigger [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	(1)
Compensation to Us	None
Maximum Exposure	$ 0.8
Financial Guarantee of External Loan to Subsidiary in Chile Expires when Loan Balance is Reduced to Zero through July 2024 - Principal and Interest are Paid Quarterly [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Collateral	None
Compensation to Us	None
Maximum Exposure	$ 3

Insurance Operations - Summary

Insurance Operations - Summary of Reconciliations of Direct to Net premiums on Written and Earned Basis Related to Wholly Owned Underwriting Enterprise Subsidiary (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Premiums Written and Earned [Abstract]
Written, Direct	$ 24.4	$ 30.9	$ 37.7
Written, Assumed	0.4	0.2	0.1
Written, Ceded	(24.8)	(31.1)	(37.8)
Earned, Direct	28.7	35.9	40.7
Earned, Assumed	0.2	0.2	0.9
Earned, Ceded	$ (28.9)	$ (36.1)	$ (41.6)

Insurance Operations - Addition

Insurance Operations - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Insurance [Abstract]
Reinsurance recoverables amount	$ 20.4	$ 28

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Expense Benefit [Line Items]
Deferred tax assets included due to deferral of payroll taxes		$ 6.5
Net unrecognized tax benefits	$ 12.3	10
Accrued interest and penalties related to unrecognized tax benefits	$ 3.4	3.3
Open tax year	2011 2012
Deferred tax liabilities	$ 598.1	521.2
Net operating loss carryforwards	$ 129.4	32.7
Net operating loss carryforward expiration year	2023
Undistributed earnings of foreign subsidiaries	$ 835.1	806
State Tax Credits [Member]
Income Tax Expense Benefit [Line Items]
Deferred tax credits	$ 14.8
Deferred tax credits expiration year	2027
General Business and Other Tax Credits [Member]
Income Tax Expense Benefit [Line Items]
Deferred tax credits	$ 757.4
Deferred tax credits expiration year	2034
Noncurrent Liabilities [Member]
Income Tax Expense Benefit [Line Items]
Deferred tax liabilities	$ 92.4	$ 165.7

Income Taxes - Components of Ea

Income Taxes - Components of Earnings Before Income Taxes and Provision for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
United States	$ 781.6	$ 593	$ 524.4
Foreign, principally Australia, Canada, New Zealand and the U.K.	545.4	382.1	346.5
Earnings before income taxes	1,327	975.1	870.9
Federal Current	109.1	44.6	43.6
Federal Deferred	(3.5)	(151.6)	(112.4)
Total Provision for income taxes, Federal	105.6	(107)	(68.8)
State and local Current	114.3	50.6	36.6
State and local Deferred	(83.5)	(11.6)	(19.3)
Total Provision for income taxes, State and local	30.8	39	17.3
Foreign Current	196.6	108.8	94.6
Foreign Deferred	(122)	(20.7)	(30.3)
Total Provision for income taxes, Foreign	74.6	88.1	64.3
Total provision for income taxes	$ 211	$ 20.1	$ 12.8

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Provision for Income Taxes with Federal Statutory Income Tax Rate (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Federal statutory rate	$ 278.7	$ 204.8	$ 182.9
State income taxes - net of federal benefit	32.9	30.7	22.2
Differences related to non U.S. operations	(31.9)	(8.7)	(2.5)
Alternative energy and other tax credits	(6.9)	(199)	(154.3)
Other permanent differences	22.5	(3.5)	(15.7)
Stock-based compensation	(59.3)	(40)	(31.4)
Changes in unrecognized tax benefits	4	0.8
Change in valuation allowance	15.5	26.4	6.5
Change in U.S. and U.K. tax rates	(44.5)	8.6	5.5
Other			(0.4)
Total provision for income taxes	$ 211	$ 20.1	$ 12.8
Federal statutory rate, % of Pretax Earnings	21%	21%	21%
State income taxes-net of Federal benefit, % of Pretax Earnings	2.50%	3.20%	2.60%
Differences related to non U.S. operations, % of Pretax Earnings	(2.40%)	(0.90%)	(0.30%)
Alternative energy and other tax credits, % of Pretax Earnings	(0.50%)	(20.40%)	(17.70%)
Other permanent differences, % of Pretax Earnings	1.70%	(0.40%)	(1.80%)
Stock-based compensation	(4.50%)	(4.10%)	(3.60%)
Changes in unrecognized tax benefits, % of Pretax Earnings	0.30%	0.10%
Change in valuation allowance, % of Pretax Earnings	1.20%	2.70%	0.70%
Change in U.S. and U.K. tax rates	(3.40%)	0.90%	0.60%
Total provision for income taxes, % of Pretax Earnings	15.90%	2.10%	1.50%

Income Taxes - Gross Unrecogniz

Income Taxes - Gross Unrecognized Tax Benefit (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at January	$ 11.7	$ 11.2
Increases in tax positions for current year	3.8	2.5
Settlements	(1.7)
Lapse in statute of limitations	(1.4)	(1.6)
Increases in tax positions for prior years	3.1	0.1
Decreases in tax positions for prior years	(2.1)	(0.5)
Gross unrecognized tax benefits at December	$ 13.4	$ 11.7

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Alternative minimum tax and other credit carryforwards	$ 772.7	$ 1,074
Accrued and unfunded compensation and employee benefits	321.8	265.6
Amortizable intangible assets	69.3	92.7
Compensation expense related to stock options	11.1	5.8
Accrued liabilities	126.6	112.1
Accrued pension liability	3.1	1.5
Investments	2.6	3.1
Net operating loss carryforwards	129.4	32.7
Capital loss carryforwards	8.1	8.9
Lease liabilities	96.5	106.4
Capitalized indirect property costs	394.1
Hedging instruments		27.3
Other	4.3	5
Total deferred tax assets	1,939.6	1,735.1
Valuation allowance for deferred tax assets	(135.2)	(154.9)
Deferred tax assets	1,804.4	1,580.2
Nondeductible amortizable intangible assets	433.9	394.7
Investment-related partnerships	6.6	4.6
Depreciable fixed assets	46.5	16.2
Right-of-use assets	88.6	96.9
Hedging instruments	10.7
Other prepaid items	11.8	8.8
Total deferred tax liabilities	598.1	521.2
Net deferred tax assets	$ 1,206.3	$ 1,059

Supplemental Disclosures of C_3

Supplemental Disclosures of Cash Flow Information - Cash Flow (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Interest paid	$ 240.2	$ 215.7	$ 188.9
Income taxes paid, net	$ 317.6	$ 325.4	$ 113

Supplemental Disclosures of C_4

Supplemental Disclosures of Cash Flow Information - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
AMT credit and other U.S. federal refunds		$ (28.5)	$ (20)
Tax-payment deferrals		20
Tax returns		106
Net operating losses in U.K. additional cash tax payments	$ 49	$ 28.4
Qualified Contributory Savings and Thrift 401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Matching contributions by employer, percentage	100%
Percentage of eligible compensation for matching contributions by employer	5%	5%
Matching contributions vesting schedule	5 years
Contribution expense to plan	$ 73.8	$ 65.7	$ 63.6
Employer matching contributions on eligible compensation	5%	5%

Supplemental Disclosures of C_5

Supplemental Disclosures of Cash Flow Information - Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 342.3	$ 402.6	$ 664.6
Restricted cash	4,621.9	4,063.7	2,909.7
Total cash, cash equivalents and restricted cash	$ 4,964.2	$ 4,466.3	$ 3,574.3

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss Attributable to Controlling Interests (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ (726.1)
Ending Balance	(1,140.4)	$ (726.1)
Pension Liability [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(37.1)	(56.1)	$ (56.5)
Net change in period	(12.3)	19	0.4
Ending Balance	(49.4)	(37.1)	(56.1)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(613.4)	(491.1)	(674.8)
Net change in period	(511.8)	(122.3)	183.7
Ending Balance	(1,125.2)	(613.4)	(491.1)
Fair Value of Derivative Investments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(75.6)	(96.4)	(28.3)
Net change in period	109.8	20.8	(68.1)
Ending Balance	34.2	(75.6)	(96.4)
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(726.1)	(643.6)	(759.6)
Net change in period	(414.3)	(82.5)	116
Ending Balance	$ (1,140.4)	$ (726.1)	$ (643.6)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Loss - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Expense related to pension liability reclassified from accumulated other comprehensive earnings	$ 2,200,000	$ 5,800,000	$ 6,100,000
Income (expense) related to fair value of derivative investments reclassified from accumulated other comprehensive earnings	3,200,000	(5,800,000)	(6,300,000)
Foreign currency translation reclassified from accumulated other comprehensive earnings	$ 0	$ 0	$ 0

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
Segment Information - Additional Information (Detail)	Dec. 31, 2022 Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Information - Schedule

Segment Information - Schedule of Segment Reporting Information by Segment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues before reimbursements	$ 8,420.1	$ 8,076.4	$ 6,851.9
Reimbursements	130.5	133	151.7
Total revenues	8,550.6	8,209.4	7,003.6
Compensation	4,799.8	3,927.5	3,466.5
Operating	1,330.9	1,072.4	906.5
Reimbursements	130.5	133	151.7
Cost of revenues from clean coal activities	22.9	1,173.2	882.1
Interest	256.9	226.1	196.4
Loss on extinguishment of debt		16.2
Depreciation	144.7	151.2	145.1
Amortization	454.9	415.1	417.3
Change in estimated acquisition earnout payables	83	119.6	(32.9)
Total expenses	7,223.6	7,234.3	6,132.7
Earnings before income taxes	1,327	975.1	870.9
Provision (benefit) for income taxes	211	20.1	12.8
Net earnings	1,116	955	858.1
Net earnings attributable to noncontrolling interests	1.8	48.2	39.3
Net earnings attributable to controlling interests	1,114.2	906.8	818.8
Net foreign exchange (loss) gain	34	(2.3)	(2.9)
Total identifiable assets	38,907.8	33,345	22,331.4
Goodwill - net	9,489.4	8,666.2	6,127
Amortizable intangible assets - net	3,372.1	3,954	2,399.9
Unites States [Member]
Segment Reporting Information [Line Items]
Total revenues	5,557.2	5,856.8	5,048.9
Total identifiable assets	21,301.8	18,828.6	11,786.3
Goodwill - net	5,140.5	4,473.9
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total revenues	1,588.4	1,245	1,034.4
Total identifiable assets	9,602.5	8,385.4	6,274.3
Goodwill - net	2,197.9	2,213.7
Australia [Member]
Segment Reporting Information [Line Items]
Total revenues	410.9	376.1	314.5
Total identifiable assets	1,886.9	1,768.9	1,462.9
Goodwill - net	477.8	498.1
Canada [Member]
Segment Reporting Information [Line Items]
Total revenues	361.9	308	249.1
Total identifiable assets	1,480.8	1,440.5	1,058.4
Goodwill - net	569.7	572.9
New Zealand [Member]
Segment Reporting Information [Line Items]
Total revenues	181.3	177	154.4
Total identifiable assets	749.8	775	790.1
Goodwill - net	213.3	227.8
Other Foreign [Member]
Segment Reporting Information [Line Items]
Total revenues	450.9	246.5	202.3
Total identifiable assets	3,886	2,146.6	959.4
Goodwill - net	890.2	679.8
Commissions [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	5,187.4	4,132.3	3,591.9
Broker Fees [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	2,567.7	2,264.1	1,957.9
Supplemental Revenue [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	284.7	248.7	221.9
Contingent Revenue [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	207.3	188	147
Investment Income [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	136.3	83.1	75.9
Net (Losses) Gains on Divestitures [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	13	18.9	(5.8)
Clean Coal Activities [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	23	1,140.8	863.5
Other income (Losses) [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	0.7	0.5	(0.4)
Brokerage [Member]
Segment Reporting Information [Line Items]
Goodwill - net	9,358.1	8,544.6	6,053.6
Brokerage [Member] \| Unites States [Member]
Segment Reporting Information [Line Items]
Goodwill - net	5,065.7	4,409.1
Brokerage [Member] \| United Kingdom [Member]
Segment Reporting Information [Line Items]
Goodwill - net	2,180.2	2,198.7
Brokerage [Member] \| Australia [Member]
Segment Reporting Information [Line Items]
Goodwill - net	467.6	487.2
Brokerage [Member] \| Canada [Member]
Segment Reporting Information [Line Items]
Goodwill - net	569.7	572.9
Brokerage [Member] \| New Zealand [Member]
Segment Reporting Information [Line Items]
Goodwill - net	203.8	217.6
Brokerage [Member] \| Other Foreign [Member]
Segment Reporting Information [Line Items]
Goodwill - net	871.1	659.1
Brokerage [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	7,303.8	5,967.5	5,167.1
Total revenues	7,303.8	5,967.5	5,167.1
Compensation	4,024.7	3,252.4	2,882.5
Operating	1,039.9	757.9	687.2
Depreciation	103.6	87.8	73.5
Amortization	448.7	407.6	411.3
Change in estimated acquisition earnout payables	90.4	116.3	(29.7)
Total expenses	5,707.3	4,622	4,024.8
Earnings before income taxes	1,596.5	1,345.5	1,142.3
Provision (benefit) for income taxes	394.7	328.9	276.3
Net earnings	1,201.8	1,016.6	866
Net earnings attributable to noncontrolling interests	4.4	8.4	4.9
Net earnings attributable to controlling interests	1,197.4	1,008.2	861.1
Net foreign exchange (loss) gain	2.6	(1.7)	(2.6)
Total identifiable assets	35,205.1	29,821	19,185.3
Goodwill - net	9,358.1	8,544.6	6,053.6
Amortizable intangible assets - net	3,325.9	3,906.1	2,376.3
Brokerage [Member] \| Operating Segments [Member] \| Unites States [Member]
Segment Reporting Information [Line Items]
Total revenues	4,503.9	3,804.8	3,369.4
Total identifiable assets	17,827.2	15,548.3	8,897.9
Brokerage [Member] \| Operating Segments [Member] \| United Kingdom [Member]
Segment Reporting Information [Line Items]
Total revenues	1,544.3	1,199	993.7
Total identifiable assets	9,486.6	8,251.3	6,135.1
Brokerage [Member] \| Operating Segments [Member] \| Australia [Member]
Segment Reporting Information [Line Items]
Total revenues	281.8	252.6	216.1
Total identifiable assets	1,797.9	1,684.2	1,373.3
Brokerage [Member] \| Operating Segments [Member] \| Canada [Member]
Segment Reporting Information [Line Items]
Total revenues	356	302.2	243.8
Total identifiable assets	1,476.4	1,436.1	1,053.6
Brokerage [Member] \| Operating Segments [Member] \| New Zealand [Member]
Segment Reporting Information [Line Items]
Total revenues	166.9	162.4	141.8
Total identifiable assets	731	754.5	766
Brokerage [Member] \| Operating Segments [Member] \| Other Foreign [Member]
Segment Reporting Information [Line Items]
Total revenues	450.9	246.5	202.3
Total identifiable assets	3,886	2,146.6	959.4
Brokerage [Member] \| Commissions [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	5,187.4	4,132.3	3,591.9
Brokerage [Member] \| Broker Fees [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	1,476.9	1,296.9	1,136.9
Brokerage [Member] \| Supplemental Revenue [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	284.7	248.7	221.9
Brokerage [Member] \| Contingent Revenue [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	207.3	188	147
Brokerage [Member] \| Investment Income [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	135.4	82.8	75.2
Brokerage [Member] \| Net (Losses) Gains on Divestitures [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	12.1	18.8	(5.8)
Risk Management [Member]
Segment Reporting Information [Line Items]
Goodwill - net	112.2	100.9	70.5
Risk Management [Member] \| Unites States [Member]
Segment Reporting Information [Line Items]
Goodwill - net	74.8	64.8
Risk Management [Member] \| United Kingdom [Member]
Segment Reporting Information [Line Items]
Goodwill - net	17.7	15
Risk Management [Member] \| Australia [Member]
Segment Reporting Information [Line Items]
Goodwill - net	10.2	10.9
Risk Management [Member] \| New Zealand [Member]
Segment Reporting Information [Line Items]
Goodwill - net	9.5	10.2
Risk Management [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	1,092.6	967.6	821.7
Reimbursements	130.5	133	151.7
Total revenues	1,223.1	1,100.6	973.4
Compensation	664.9	580.7	517.5
Operating	233.9	209.8	162.6
Reimbursements	130.5	133	151.7
Depreciation	37.8	46.2	49.4
Amortization	6.2	7.5	6
Change in estimated acquisition earnout payables	(7.4)	3.3	(3.2)
Total expenses	1,065.9	980.5	884
Earnings before income taxes	157.2	120.1	89.4
Provision (benefit) for income taxes	41.4	30.6	22.5
Net earnings	115.8	89.5	66.9
Net earnings attributable to controlling interests	115.8	89.5	66.9
Net foreign exchange (loss) gain	31.4		(0.1)
Total identifiable assets	1,142.5	1,034.4	973.9
Goodwill - net	112.2	100.9	70.5
Amortizable intangible assets - net	46.2	47.9	23.6
Risk Management [Member] \| Operating Segments [Member] \| Unites States [Member]
Segment Reporting Information [Line Items]
Total revenues	1,029.6	910.7	816.4
Total identifiable assets	914.4	790.7	716.2
Risk Management [Member] \| Operating Segments [Member] \| United Kingdom [Member]
Segment Reporting Information [Line Items]
Total revenues	44.1	46	40.7
Total identifiable assets	115.9	134.1	139.2
Risk Management [Member] \| Operating Segments [Member] \| Australia [Member]
Segment Reporting Information [Line Items]
Total revenues	129.1	123.5	98.4
Total identifiable assets	89	84.7	89.6
Risk Management [Member] \| Operating Segments [Member] \| Canada [Member]
Segment Reporting Information [Line Items]
Total revenues	5.9	5.8	5.3
Total identifiable assets	4.4	4.4	4.8
Risk Management [Member] \| Operating Segments [Member] \| New Zealand [Member]
Segment Reporting Information [Line Items]
Total revenues	14.4	14.6	12.6
Total identifiable assets	18.8	20.5	24.1
Risk Management [Member] \| Broker Fees [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	1,090.8	967.2	821
Risk Management [Member] \| Investment Income [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	0.9	0.3	0.7
Risk Management [Member] \| Net (Losses) Gains on Divestitures [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	0.9	0.1
Corporate [Member]
Segment Reporting Information [Line Items]
Goodwill - net	19.1	20.7	2.9
Corporate [Member] \| Other Foreign [Member]
Segment Reporting Information [Line Items]
Goodwill - net	19.1	20.7
Corporate [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	23.7	1,141.3	863.1
Total revenues	23.7	1,141.3	863.1
Compensation	110.2	94.4	66.5
Operating	57.1	104.7	56.7
Cost of revenues from clean coal activities	22.9	1,173.2	882.1
Interest	256.9	226.1	196.4
Loss on extinguishment of debt		16.2
Depreciation	3.3	17.2	22.2
Total expenses	450.4	1,631.8	1,223.9
Earnings before income taxes	(426.7)	(490.5)	(360.8)
Provision (benefit) for income taxes	(225.1)	(339.4)	(286)
Net earnings	(201.6)	(151.1)	(74.8)
Net earnings attributable to noncontrolling interests	(2.6)	39.8	34.4
Net earnings attributable to controlling interests	(199)	(190.9)	(109.2)
Net foreign exchange (loss) gain		(0.6)	(0.2)
Total identifiable assets	2,560.2	2,489.6	2,172.2
Goodwill - net	19.1	20.7	2.9
Corporate [Member] \| Operating Segments [Member] \| Unites States [Member]
Segment Reporting Information [Line Items]
Total revenues	23.7	1,141.3	863.1
Total identifiable assets	2,560.2	2,489.6	2,172.2
Corporate [Member] \| Clean Coal Activities [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	23	1,140.8	863.5
Corporate [Member] \| Other income (Losses) [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues before reimbursements	$ 0.7	$ (0.5)	$ (0.4)

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year		$ 8.3	$ 10.1	$ 8.7
Amounts Recorded in Earnings		6.8	7	6.6
Adjustments	[1]	(4)	(8.8)	(5.2)
Balance at End of Year		11.1	8.3	10.1
Allowance for Estimated Policy Cancellations [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year		10	9.9	8.3
Amounts Recorded in Earnings		2.4	(1.3)	4.1
Adjustments	[2]	(3.1)	1.4	(2.5)
Balance at End of Year		9.3	10	9.9
Valuation Allowance for Deferred Tax Assets [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year		154.9	94.9	80.5
Amounts Recorded in Earnings		(19.7)	60	14.4
Balance at End of Year		135.2	154.9	94.9
Accumulated Amortization of Expiration Lists, Non-compete Agreements and Trade Names [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year		2,924	2,537	2,087.5
Amounts Recorded in Earnings		454.9	415.1	417.3
Adjustments	[3]	(78.9)	(28.1)	32.2
Balance at End of Year		$ 3,300	$ 2,924	$ 2,537

[1] Net activity of bad debt write offs and recoveries and acquired businesses. Additions to allowance related to acquired businesses. Elimination of fully amortized expiration lists, non-compete agreements and trade names, intangible asset/amortization reclassifications and disposal of acquired businesses.