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Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2024 | Mar. 31, 2023 | Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Carrying value of investment | $ 272 |  | $ 266
Gain (loss) on equity securities | 2 | $ 1 |
Equity investments without readily determinable market value | 19 |  | 20
Private Insurance and Consulting |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Carrying value of investment | 64 |  | 63
Private Equity Investments |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Carrying value of investment | 208 |  | 203
Equity method investment income (loss) | (1) | $ 3 |
Commitments for potential future investments | 109 |  |
Equity Investments |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Equity securities | $ 18 |  | $ 16
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 |

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