Principles of Consolidation and Other Matters	3 Months Ended
Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation and Other Matters	Principles of Consolidation and Other Matters The Company prepared the consolidated financial statements included herein pursuant to the rules and regulations of the Securities and Exchange Commission. For interim filings, certain information and disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (U.S.) have been omitted pursuant to such rules and regulations. The Company believes that the information and disclosures presented are adequate to make such information and disclosures not misleading. These consolidated financial statements should be read in conjunction with the consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 (the "2023 Form 10-K"). The accompanied consolidated financial statements include all wholly-owned and majority owned subsidiaries. All significant inter-company transactions and balances have been eliminated. The financial information contained herein reflects all normal recurring adjustments which are, in the opinion of management, necessary for a fair presentation of the Company’s consolidated financial statements as of and for the three months ended March 31, 2024 and 2023. The preparation of the consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period. On an ongoing basis, the Company evaluates its estimates, judgments and methodologies. The estimates are based on historical experience and on various other assumptions that the Company believes are reasonable. Such matters include: •estimates of revenue; •impairment assessments and charges; •recoverability of long-lived assets; •liabilities for errors and omissions; •deferred tax assets, uncertain tax positions and income tax expense; •share-based and incentive compensation expense; •the allowance for current expected credit losses on receivables; •useful lives assigned to long-lived assets, and depreciation and amortization; and •fair value estimates of contingent consideration receivable or payable related to acquisitions or dispositions. The Company believes these estimates are reasonable based on information currently available at the time they are made. The Company also considered the potential impact of macroeconomic factors including from the multiple major wars, escalating conflict throughout the Middle East and rising tension in the South China Sea, slower GDP growth or recession, lower interest rates, capital markets volatility and inflation to its customer base in various industries and geographies. Insurance exposures subject to variable factors are subject to mid-term and end-of-term adjustments, as well as policy audits, which may reduce premiums and corresponding commissions. Estimates were updated based on internal and industry specific economic data. Actual results may differ from these estimates. Cash and Cash Equivalents Cash and cash equivalents primarily consist of certificates of deposit and time deposits, with original maturities of three months or less, and money market funds. The estimated fair value of the Company's cash and cash equivalents approximates their carrying value. The Company is required to maintain operating funds primarily related to regulatory requirements outside of the U.S. or as collateral under captive insurance arrangements. At March 31, 2024, the Company maintained $480 million compared to $486 million at December 31, 2023 related to these regulatory requirements. Allowance for Credit Losses on Accounts Receivable The Company’s policy for providing an allowance for credit losses on its accounts receivable is based on a combination of factors, including historical write-offs, aging of balances, and other qualitative and quantitative analyses. The charge related to expected credit losses was not material to the consolidated statements of income for the three months ended March 31, 2024 and 2023, respectively. Investments The caption "Investment income" in the consolidated statements of income comprises realized and unrealized gains and losses from investments recognized in earnings. It includes, when applicable, other than temporary declines in the value of securities, mark-to-market increases or decreases in equity investments with readily determinable fair values and equity method gains or losses on the Company's investments in private equity funds. The Company holds investments in certain private equity funds. Investments in private equity funds are accounted for in accordance with the equity method of accounting using a consistently applied three-month lag period adjusted for any known significant changes from the lag period to the reporting date of the Company. The underlying private equity funds follow investment company accounting, where investments within the fund are carried at fair value. Investment gains or losses for its proportionate share of the change in fair value of the funds are recorded in earnings. Investments accounted for in accordance with the equity method of accounting are included in other assets in the consolidated balance sheets. The Company recorded net investment income of $1 million and $2 million for the three months ended March 31, 2024 and 2023, respectively. Income Taxes The Company's effective tax rate for the three months ended March 31, 2024 was 23.9%, compared with 24.7% for the corresponding quarter of 2023. The tax rate in each period reflects the impact of discrete tax items such as excess tax benefits related to share-based compensation, enacted tax legislation, changes in uncertain tax positions, deferred tax adjustments, non-taxable adjustments related to contingent consideration for acquisitions, and valuation allowances for certain tax credits and attributes. The rate for the three months ended March 31, 2024 reflects the previously enacted change in the United Kingdom (U.K.) corporate income tax rate from 19% to 25%, which was effective April 1, 2023. The blended U.K. statutory tax rate for 2023 was 23.5%. The excess tax benefit related to share-based payments is the most significant discrete item in both periods, reducing the effective tax rate by 2.3% and 1.3% for the three months ended March 31, 2024 and 2023, respectively. The Company's tax rate reflects its income, statutory tax rates, and tax planning in the various jurisdictions in which it operates. Significant judgment is required in determining the annual effective tax rate and in evaluating uncertain tax positions. Losses in one jurisdiction, generally, cannot offset earnings in another, and within certain jurisdictions profits and losses may not offset between entities. Consequently, losses in certain jurisdictions may require valuation allowances affecting the effective tax rate, depending on estimates of the realizability of associated deferred tax assets. The tax rate is also sensitive to changes in unrecognized tax benefits, including the impact of settled tax audits and expired statutes of limitations. The Company reports a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in tax returns. The Company's gross unrecognized tax benefits were $127 million at March 31, 2024, and $124 million at December 31, 2023. It is reasonably possible that the total amount of unrecognized tax benefits could decrease up to approximately $66 million within the next twelve months due to settlement of audits and expirations of statutes of limitations. Changes in tax laws, rulings, policies, or related legal and regulatory interpretations occur frequently and may have significant favorable or adverse impacts on our effective tax rate. In 2021, the Organization for Economic Cooperation and Development ("OECD") released model rules for a 15% global minimum tax, known as Pillar Two. Pillar Two has now been enacted by approximately 30 countries, including the U.K. and Ireland. This minimum tax is treated as a period cost beginning in 2024 and does not have a material impact on the Company's financial results of operations for the current period. The Company is monitoring legislative developments, as well as additional guidance from countries that have enacted legislation. We anticipate further legislative activity and administrative guidance in 2024. Restructuring Costs Charges associated with restructuring activities are recognized in accordance with applicable accounting guidance which includes accounting for disposal or exit activities, guidance related to impairment of right-of-use ("ROU") assets related to real estate leases, as well as other costs resulting from accelerated depreciation or amortization of leasehold improvements and other property and equipment. Severance and related costs are recognized based on amounts due under established severance plans or estimates of one-time benefits that will be provided. Typically, severance benefits are recognized when the impacted colleagues are notified of their expected termination and such termination is expected to occur within the legally required notification period. These costs are included in compensation and benefits in the consolidated statements of income. Costs for real estate consolidation are recognized based on the type of cost, and the expected future use of the facility. For locations where the Company does not expect to sub-lease the property, the amortization of any ROU asset is accelerated from the decision date to the cease use date. For locations where the Company expects to sub-lease the properties subsequent to its vacating the property, the ROU asset is reviewed for potential impairment at the earlier of the cease use date or the date a sub-lease is signed. To determine the amount of impairment, the fair value of the ROU asset is determined based on the present value of the estimated net cash flows related to the property. Contractual costs outside of the ROU asset are recognized based on the net present value of expected future cash outflows for which the Company will not receive any benefit. Such amounts are reliant on estimates of future sub-lease income to be received and future contractual costs to be incurred. These costs are included in other operating expenses in the consolidated statements of income. Other costs related to restructuring, such as moving, legal or consulting costs are recognized as incurred. These costs are included in other operating expenses in the consolidated statements of income. Foreign Currency The financial statements of our international subsidiaries are translated from functional currency to U.S. dollars using month-end exchange rates for assets and liabilities, and average monthly exchange rates during the period for revenues and expenses. Translation adjustments are recorded in accumulated other comprehensive income (loss) ("AOCI") within the consolidated statements of equity. Foreign exchange transaction gains and losses resulting from the conversion of the transaction currency to functional currency are included in operating income in the consolidated statements of income.

The Company prepared the consolidated financial statements included herein pursuant to the rules and regulations of the Securities and Exchange Commission. For interim filings, certain information and disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (U.S.) have been omitted pursuant to such rules and regulations. The Company believes that the information and disclosures presented are adequate to make such information and disclosures not misleading. These consolidated financial statements should be read in conjunction with the consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 (the "2023 Form 10-K").

The financial information contained herein reflects all normal recurring adjustments which are, in the opinion of management, necessary for a fair presentation of the Company’s consolidated financial statements as of and for the three months ended March 31, 2024 and 2023.

The preparation of the consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period.

The Company believes these estimates are reasonable based on information currently available at the time they are made. The Company also considered the potential impact of macroeconomic factors including from the multiple major wars, escalating conflict throughout the Middle East and rising tension in the South China Sea, slower GDP growth or recession, lower interest rates, capital markets volatility and inflation to its customer base in various industries and geographies. Insurance exposures subject to variable factors are subject to mid-term and end-of-term adjustments, as well as policy audits, which may reduce premiums and corresponding commissions. Estimates were updated based on internal and industry specific economic data. Actual results may differ from these estimates.

Cash and cash equivalents primarily consist of certificates of deposit and time deposits, with original maturities of three months or less, and money market funds. The estimated fair value of the Company's cash and cash equivalents approximates their carrying value. The Company is required to maintain operating funds primarily related to regulatory requirements outside of the U.S. or as collateral under captive insurance arrangements. At March 31, 2024, the Company maintained $480 million compared to $486 million at December 31, 2023 related to these regulatory requirements.

The Company’s policy for providing an allowance for credit losses on its accounts receivable is based on a combination of factors, including historical write-offs, aging of balances, and other qualitative and quantitative analyses. The charge related to expected credit losses was not material to the consolidated statements of income for the three months ended March 31, 2024 and 2023, respectively.

The caption "Investment income" in the consolidated statements of income comprises realized and unrealized gains and losses from investments recognized in earnings. It includes, when applicable, other than temporary declines in the value of securities, mark-to-market increases or decreases in equity investments with readily determinable fair values and equity method gains or losses on the Company's investments in private equity funds.

The Company holds investments in certain private equity funds. Investments in private equity funds are accounted for in accordance with the equity method of accounting using a consistently applied three-month lag period adjusted for any known significant changes from the lag period to the reporting date of the Company. The underlying private equity funds follow investment company accounting, where investments within the fund are carried at fair value. Investment gains or losses for its proportionate share of the change in fair value of the funds are recorded in earnings. Investments accounted for in accordance with the equity method of accounting are included in other assets in the consolidated balance sheets.

The tax rate in each period reflects the impact of discrete tax items such as excess tax benefits related to share-based compensation, enacted tax legislation, changes in uncertain tax positions, deferred tax adjustments, non-taxable adjustments related to contingent consideration for acquisitions, and valuation allowances for certain tax credits and attributes. The rate for the three months ended March 31, 2024 reflects the previously enacted change in the United Kingdom (U.K.) corporate income tax rate from 19% to 25%, which was effective April 1, 2023. The blended U.K. statutory tax rate for 2023 was 23.5%.

Losses in one jurisdiction, generally, cannot offset earnings in another, and within certain jurisdictions profits and losses may not offset between entities. Consequently, losses in certain jurisdictions may require valuation allowances affecting the effective tax rate, depending on estimates of the realizability of associated deferred tax assets. The tax rate is also sensitive to changes in unrecognized tax benefits, including the impact of settled tax audits and expired statutes of limitations.

The Company reports a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in tax returns. The Company's gross unrecognized tax benefits were $127 million at March 31, 2024, and $124 million at December 31, 2023. It is reasonably possible that the total amount of unrecognized tax benefits could decrease up to approximately $66 million within the next twelve months due to settlement of audits and expirations of statutes of limitations.

Changes in tax laws, rulings, policies, or related legal and regulatory interpretations occur frequently and may have significant favorable or adverse impacts on our effective tax rate. In 2021, the Organization for Economic Cooperation and Development ("OECD") released model rules for a 15% global minimum tax, known as Pillar Two. Pillar Two has now been enacted by approximately 30 countries, including the U.K. and Ireland. This minimum tax is treated as a period cost beginning in 2024 and does not have a material impact on the Company's financial results of operations for the current period. The Company is monitoring legislative developments, as well as additional guidance from countries that have enacted legislation. We anticipate further legislative activity and administrative guidance in 2024.

Charges associated with restructuring activities are recognized in accordance with applicable accounting guidance which includes accounting for disposal or exit activities, guidance related to impairment of right-of-use ("ROU") assets related to real estate leases, as well as other costs resulting from accelerated depreciation or amortization of leasehold improvements and other property and equipment.

Severance and related costs are recognized based on amounts due under established severance plans or estimates of one-time benefits that will be provided. Typically, severance benefits are recognized when the impacted colleagues are notified of their expected termination and such termination is expected to occur within the legally required notification period. These costs are included in compensation and benefits in the consolidated statements of income.

Costs for real estate consolidation are recognized based on the type of cost, and the expected future use of the facility. For locations where the Company does not expect to sub-lease the property, the amortization of any ROU asset is accelerated from the decision date to the cease use date. For locations where the Company expects to sub-lease the properties subsequent to its vacating the property, the ROU asset is reviewed for potential impairment at the earlier of the cease use date or the date a sub-lease is signed. To determine the amount of impairment, the fair value of the ROU asset is determined based on the present value of the estimated net cash flows related to the property. Contractual costs outside of the ROU asset are recognized based on the net present value of expected future cash outflows for which the Company will not receive any benefit. Such amounts are reliant on estimates of future sub-lease income to be received and future contractual costs to be incurred. These costs are included in other operating expenses in the consolidated statements of income. Other costs related to restructuring, such as moving, legal or consulting costs are recognized as incurred. These costs are included in other operating expenses in the consolidated statements of income.