Principles of Consolidation and Other Matters	9 Months Ended
Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation and Other Matters	Principles of Consolidation and Other Matters The consolidated financial statements included herein have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission. While certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been omitted pursuant to such rules and regulations for interim filings, 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, 2018 (the "2018 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 and nine month periods ended September 30, 2019 and 2018. 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 United States or as collateral under captive insurance arrangements. At September 30, 2019, the Company maintained $193 million compared to $186 million at December 31, 2018 related to these regulatory requirements. 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 that are accounted for under 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 the Company's proportionate share of the change in fair value of the funds are recorded in earnings. Investments accounted for using the equity method of accounting are included in "other assets" in the consolidated balance sheets. The Company recorded net investment income of $7 million and $20 million for the three and nine month periods ended September 30, 2019 compared to net investment losses of $52 million and $24 million for the three and nine month periods ended September 30, 2018. The three and nine month periods ending September 30, 2019 includes gains of $4 million and $10 million related to mark-to-market changes in equity securities and gains of $3 million and $10 million related to investments in private equity funds and other investments. The three and nine months periods ending September 30, 2018 include an $81 million impairment charge related to an other than temporary decline in the Company's equity method investment in Alexander Forbes (see Note 10). The three and nine month periods ending September 30, 2018 also include gains of $25 million and $43 million, respectively, related to mark-to-market changes in equity securities and $4 million and $14 million, respectively, related to investments in private equity funds and other investments. Leases Effective January 1, 2019, the Company adopted the new accounting standard related to leases. Under the new standard, a lessee is required to recognize assets and liabilities for its leases with lease terms of more than 12 months. The Company adopted this new standard using the modified retrospective method, which applies the new guidance beginning with the year of adoption, with the cumulative effect of initially applying the standard recognized as an adjustment to retained earnings at January 1, 2019. There was no cumulative-effect adjustment required to be recorded to retained earnings upon transition. Prior period results have not been restated to reflect the adoption of this new standard. On January 1, 2019, the Company recognized a lease liability of $1.9 billion and a corresponding right-of-use asset ("ROU asset") of $1.7 billion, including the reclassification of approximately $200 million of unamortized lease incentives and restructuring liabilities, upon the adoption of this standard, with minimal impact on the consolidated statement of income. See Note 12 for further information related to Leases. Income Taxes The Company's effective tax rate in the third quarter of 2019 was 26.0% compared with 27.5% in the third quarter of 2018. The effective tax rates for the first nine months of 2019 and 2018 were 27.8% and 25.2%, respectively. The rate in the first nine months of 2019 reflects discrete adjustments related to the JLT acquisition, including tax on the disposition of JLT’s aerospace business and nondeductible expenses incurred in connection with the Transaction. The rate in the third quarter of 2018 as well as the first nine months of 2018 reflect the impact of a charge related to the Company’s investment in Alexander Forbes as discussed in Note 10, largely offset by favorable adjustments to the estimated impact of tax reform. Both periods reflect the effect of other discrete tax matters such as excess tax benefits related to share-based compensation, tax legislation, changes in uncertain tax positions, deferred tax adjustments and nontaxable adjustments to contingent acquisition consideration. The Company is routinely examined by tax authorities in the jurisdictions in which it has significant operations. The Company regularly considers the likelihood of assessments in each of the taxing jurisdictions resulting from examinations. When evaluating the potential imposition of penalties, the Company considers a number of relevant factors under penalty statutes, including appropriate disclosure of the tax return position, the existence of legal authority supporting the Company's position, and reliance on the opinion of professional tax advisors. 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 decreased from $78 million at December 31, 2018 to $76 million at September 30, 2019 due to settlements of audits and expirations of statutes of limitation partially offset by current accruals. It is reasonably possible that the total amount of unrecognized tax benefits will decrease between zero and approximately $7 million within the next twelve months due to settlements of audits and expirations of statutes of limitation. Integration and Restructuring Charges 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 right-of-use 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 right-of-use 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 right-of-use asset is determined based on the present value of the estimated net cash flows related to the property. Contractual costs outside of the right-of-use asset are recognized based on their 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 integration and 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.

The consolidated financial statements included herein have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission. While certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been omitted pursuant to such rules and regulations for interim filings, 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, 2018 (the "2018 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 and nine month periods ended September 30, 2019 and 2018.

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 United States or as collateral under captive insurance arrangements. At September 30, 2019, the Company maintained $193 million compared to $186 million at December 31, 2018 related to these regulatory requirements.

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 that are accounted for under 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 the Company's proportionate share of the change in fair value of the funds are recorded in earnings. Investments accounted for using the equity method of accounting are included in "other assets" in the consolidated balance sheets.

The Company recorded net investment income of $7 million and $20 million for the three and nine month periods ended September 30, 2019 compared to net investment losses of $52 million and $24 million for the three and nine month periods ended September 30, 2018. The three and nine month periods ending September 30, 2019 includes gains of $4 million and $10 million related to mark-to-market changes in equity securities and gains of $3 million and $10 million related to investments in private equity funds and other investments. The three and nine months periods ending September 30, 2018 include an $81 million impairment charge related to an other than temporary decline in the Company's equity method investment in Alexander Forbes (see Note 10). The three and nine month periods ending September 30, 2018 also include gains of $25 million and $43 million, respectively, related to mark-to-market changes in equity securities and $4 million and $14 million, respectively, related to investments in private equity funds and other investments.

Effective January 1, 2019, the Company adopted the new accounting standard related to leases. Under the new standard, a lessee is required to recognize assets and liabilities for its leases with lease terms of more than 12 months. The Company adopted this new standard using the modified retrospective method, which applies the new guidance beginning with the year of adoption, with the cumulative effect of initially applying the standard recognized as an adjustment to retained earnings at January 1, 2019. There was no cumulative-effect adjustment required to be recorded to retained earnings upon transition. Prior period results have not been restated to reflect the adoption of this new standard.

On January 1, 2019, the Company recognized a lease liability of $1.9 billion and a corresponding right-of-use asset ("ROU asset") of $1.7 billion, including the reclassification of approximately $200 million of unamortized lease incentives and restructuring liabilities, upon the adoption of this standard, with minimal impact on the consolidated statement of income.

The Company's effective tax rate in the third quarter of 2019 was 26.0% compared with 27.5% in the third quarter of 2018. The effective tax rates for the first nine months of 2019 and 2018 were 27.8% and 25.2%, respectively. The rate in the first nine months of 2019 reflects discrete adjustments related to the JLT acquisition, including tax on the disposition of JLT’s aerospace business and nondeductible expenses incurred in connection with the Transaction. The rate in the third quarter of 2018 as well as the first nine months of 2018 reflect the impact of a charge related to the Company’s investment in Alexander Forbes as discussed in Note 10, largely offset by favorable adjustments to the estimated impact of tax reform. Both periods reflect the effect of other discrete tax matters such as excess tax benefits related to share-based compensation, tax legislation, changes in uncertain tax positions, deferred tax adjustments and nontaxable adjustments to contingent acquisition consideration.

The Company is routinely examined by tax authorities in the jurisdictions in which it has significant operations. The Company regularly considers the likelihood of assessments in each of the taxing jurisdictions resulting from examinations. When evaluating the potential imposition of penalties, the Company considers a number of relevant factors under penalty statutes, including appropriate disclosure of the tax return position, the existence of legal authority supporting the Company's position, and reliance on the opinion of professional tax advisors.

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 decreased from $78 million at December 31, 2018 to $76 million at September 30, 2019 due to settlements of audits and expirations of statutes of limitation partially offset by current accruals. It is reasonably possible that the total amount of unrecognized tax benefits will decrease between zero and approximately $7 million within the next twelve months due to settlements of audits and expirations of statutes of limitation.

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 right-of-use 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 right-of-use 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 right-of-use asset is determined based on the present value of the estimated net cash flows related to the property. Contractual costs outside of the right-of-use asset are recognized based on their 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.