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Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Financial instruments owned: |  |
Exchange traded equity securities | $ 19 | $ 16
Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Exchange traded equity securities | 8 | 5
Mutual funds | 189 | 178
Money market funds | 440 | 606
Contingent purchase consideration assets | 0 | 1
Total assets measured at fair value | 637 | 790
Fiduciary Assets: |  |
Total fiduciary assets measured at fair value | 66 | 180
Liabilities: |  |
Contingent purchase consideration liabilities | 168 | 252
Total liabilities measured at fair value | 168 | 252
Identical Assets (Level 1) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Exchange traded equity securities | 8 | 5
Mutual funds | 189 | 178
Money market funds | 440 | 606
Contingent purchase consideration assets | 0 | 0
Total assets measured at fair value | 637 | 789
Fiduciary Assets: |  |
Total fiduciary assets measured at fair value | 66 | 180
Liabilities: |  |
Contingent purchase consideration liabilities | 0 | 0
Total liabilities measured at fair value | 0 | 0
Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Exchange traded equity securities | 0 | 0
Mutual funds | 0 | 0
Money market funds | 0 | 0
Contingent purchase consideration assets | 0 | 0
Total assets measured at fair value | 0 | 0
Fiduciary Assets: |  |
Total fiduciary assets measured at fair value | 0 | 0
Liabilities: |  |
Contingent purchase consideration liabilities | 0 | 0
Total liabilities measured at fair value | 0 | 0
Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |
Financial instruments owned: |  |
Exchange traded equity securities | 0 | 0
Mutual funds | 0 | 0
Money market funds | 0 | 0
Contingent purchase consideration assets | 0 | 1
Total assets measured at fair value | 0 | 1
Fiduciary Assets: |  |
Total fiduciary assets measured at fair value | 0 | 0
Liabilities: |  |
Contingent purchase consideration liabilities | 168 | 252
Total liabilities measured at fair value | 168 | 252
Money market funds | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Total fiduciary assets measured at fair value | 66 | 180
Money market funds | Identical Assets (Level 1) | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Total fiduciary assets measured at fair value | 66 | 180
Money market funds | Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Total fiduciary assets measured at fair value | 0 | 0
Money market funds | Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |
Fiduciary Assets: |  |
Total fiduciary assets measured at fair value | $ 0 | $ 0

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- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
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