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Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions | Sep. 30, 2022 | Dec. 31, 2021
--- | --- | ---
Financial instruments owned: |  |
Exchange traded equity securities | $ 17 | $ 75
Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Total assets measured at fair value | 248 | 691
Fiduciary Assets: |  |
Fiduciary assets | 126 | 582
Liabilities: |  |
Total liabilities measured at fair value | 328 | 352
Identical Assets (Level 1) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Total assets measured at fair value | 246 | 678
Fiduciary Assets: |  |
Fiduciary assets | 126 | 582
Liabilities: |  |
Total liabilities measured at fair value | 0 | 0
Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Total assets measured at fair value | 0 | 8
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Liabilities: |  |
Total liabilities measured at fair value | 0 | 0
Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Total assets measured at fair value | 2 | 5
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Liabilities: |  |
Total liabilities measured at fair value | 328 | 352
U.S. treasury bills | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 55
U.S. treasury bills | Identical Assets (Level 1) | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 55
U.S. treasury bills | Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
U.S. treasury bills | Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Money market funds | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Fiduciary assets | 126 | 527
Money market funds | Identical Assets (Level 1) | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Fiduciary assets | 126 | 527
Money market funds | Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Money market funds | Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Other Assets | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Exchange traded equity securities | 4 | 61
Mutual funds | 153 | 192
Other equity investment | 0 | 8
Other Assets | Identical Assets (Level 1) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Exchange traded equity securities | 4 | 61
Mutual funds | 153 | 192
Other equity investment | 0 | 0
Other Assets | Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Exchange traded equity securities | 0 | 0
Mutual funds | 0 | 0
Other equity investment | 0 | 8
Other Assets | Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Exchange traded equity securities | 0 | 0
Mutual funds | 0 | 0
Other equity investment | 0 | 0
Cash and Cash Equivalents | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Money market funds | 89 | 425
Cash and Cash Equivalents | Identical Assets (Level 1) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Money market funds | 89 | 425
Cash and Cash Equivalents | Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Money market funds | 0 | 0
Cash and Cash Equivalents | Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Money market funds | 0 | 0
Other Receivables | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Contingent purchase consideration assets | 2 | 5
Other Receivables | Identical Assets (Level 1) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Contingent purchase consideration assets | 0 | 0
Other Receivables | Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Contingent purchase consideration assets | 0 | 0
Other Receivables | Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Contingent purchase consideration assets | 2 | 5
Accounts Payable and Accrued Liabilities and Other Liabilities | Fair Value, Measurements, Recurring |  |
Liabilities: |  |
Contingent purchase consideration liability | 328 | 352
Accounts Payable and Accrued Liabilities and Other Liabilities | Identical Assets (Level 1) | Fair Value, Measurements, Recurring |  |
Liabilities: |  |
Contingent purchase consideration liability | 0 | 0
Accounts Payable and Accrued Liabilities and Other Liabilities | Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |
Liabilities: |  |
Contingent purchase consideration liability | 0 | 0
Accounts Payable and Accrued Liabilities and Other Liabilities | Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |
Liabilities: |  |
Contingent purchase consideration liability | $ 328 | $ 352

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