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Proceeds From Contingent Purchase Consideration, Asset

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

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Amount of unrealized and realized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount of investment in equity security without readily determinable fair value.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of gain (loss) included in earnings for investments classified as other.

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Amount of income (loss) for proportionate share of equity method investee's income (loss).

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Amount of cash inflow from the sale of investments classified as other.

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Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Nov. 30, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value of investment	$ 222		$ 222		$ 207
Equity securities	17		17		75
Gain on equity securities			11	$ 3
Equity investments without readily determinable market value	38		38		$ 36
Proceeds from sale of other investments	62
Loss on sale of other investments	(4)
Marsh India Insurance Brokers Limited
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Percentage of ownership in equity investment					92.00%	49.00%
Private Insurance and Consulting
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value of investment	57		57		$ 58
Private Equity Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value of investment	165		165		$ 149
Equity method income	$ 3	$ 13	23	$ 40
Unobservable Inputs (Level 3) \| Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Proceeds from contingent purchase consideration, asset			$ 3
Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revenue target period (in years)			2 years	2 years
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revenue target period (in years)			4 years	4 years