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- Definition

Commitments for Potential Future Investments

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- Definition

Proceeds From Contingent Purchase Consideration, Asset

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- Definition

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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- Definition

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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- Definition

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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- Definition

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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- Definition

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

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- Definition

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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No definition available.

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- Definition

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

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- Definition

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

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- Definition

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

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Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Nov. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity method investments	$ 266	$ 215
Gain (loss) on equity securities	(1)	11	$ 5
Equity investments without readily determinable market value	20	42
Investments for cash proceeds		62
Net loss recorded		4
Marsh India
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Percentage of interest acquired			92.00%	49.00%	49.00%
Significant 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
Private Insurance and Consulting
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity method investments	63	56
Private Equity Investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity method investments	203	159
Equity method income	7	18	$ 56
Commitments for potential future investments	121
Equity Investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, fair value	$ 16	$ 17
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