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Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions | Jun. 30, 2019 | Dec. 31, 2018
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Financial instruments owned: |  |
Total assets measured at fair value | $ 301 | $ 410
Fiduciary Assets: |  |
Fiduciary assets | 347 | 100
Liabilities: |  |
Total liabilities measured at fair value | 196 | 624
Identical Assets (Level 1) |  |
Financial instruments owned: |  |
Total assets measured at fair value | 228 | 402
Fiduciary Assets: |  |
Fiduciary assets | 347 | 100
Liabilities: |  |
Total liabilities measured at fair value | 0 | 0
Observable Inputs (Level 2) |  |
Financial instruments owned: |  |
Total assets measured at fair value | 8 | 8
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Liabilities: |  |
Total liabilities measured at fair value | 0 | 116
Unobservable Inputs (Level 3) |  |
Financial instruments owned: |  |
Total assets measured at fair value | 65 | 0
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Liabilities: |  |
Total liabilities measured at fair value | 196 | 508
US Treasury Bills |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 20
US Treasury Bills | Identical Assets (Level 1) |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 20
US Treasury Bills | Observable Inputs (Level 2) |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
US Treasury Bills | Unobservable Inputs (Level 3) |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Money Market Funds |  |
Fiduciary Assets: |  |
Fiduciary assets | 347 | 80
Money Market Funds | Identical Assets (Level 1) |  |
Fiduciary Assets: |  |
Fiduciary assets | 347 | 80
Money Market Funds | Observable Inputs (Level 2) |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Money Market Funds | Unobservable Inputs (Level 3) |  |
Fiduciary Assets: |  |
Fiduciary assets | 0 | 0
Forward Contracts |  |
Liabilities: |  |
Acquisition related derivative contract | 0 | 441
Forward Contracts | Identical Assets (Level 1) |  |
Liabilities: |  |
Acquisition related derivative contract | 0 | 0
Forward Contracts | Observable Inputs (Level 2) |  |
Liabilities: |  |
Acquisition related derivative contract | 0 | 116
Forward Contracts | Unobservable Inputs (Level 3) |  |
Liabilities: |  |
Acquisition related derivative contract | 0 | 325
Other Assets |  |
Financial instruments owned: |  |
Exchange traded equity securities | 4 | 133
Mutual funds | 153 | 151
Other equity investments | 8 | 8
Contingent purchase consideration asset | 65 | 0
Other Assets | Identical Assets (Level 1) |  |
Financial instruments owned: |  |
Exchange traded equity securities | 4 | 133
Mutual funds | 153 | 151
Other equity investments | 0 | 0
Contingent purchase consideration asset | 0 | 0
Other Assets | Observable Inputs (Level 2) |  |
Financial instruments owned: |  |
Exchange traded equity securities | 0 | 0
Mutual funds | 0 | 0
Other equity investments | 8 | 8
Contingent purchase consideration asset | 0 | 0
Other Assets | Unobservable Inputs (Level 3) |  |
Financial instruments owned: |  |
Exchange traded equity securities | 0 | 0
Mutual funds | 0 | 0
Other equity investments | 0 | 0
Contingent purchase consideration asset | 65 | 0
Cash and Cash Equivalents |  |
Financial instruments owned: |  |
Money market funds | 71 | 118
Cash and Cash Equivalents | Identical Assets (Level 1) |  |
Financial instruments owned: |  |
Money market funds | 71 | 118
Cash and Cash Equivalents | Observable Inputs (Level 2) |  |
Financial instruments owned: |  |
Money market funds | 0 | 0
Cash and Cash Equivalents | Unobservable Inputs (Level 3) |  |
Financial instruments owned: |  |
Money market funds | 0 | 0
Accounts Payable and Accrued Liabilities and Other Liabilities |  |
Liabilities: |  |
Contingent purchase consideration liability | 196 | 183
Accounts Payable and Accrued Liabilities and Other Liabilities | Identical Assets (Level 1) |  |
Liabilities: |  |
Contingent purchase consideration liability | 0 | 0
Accounts Payable and Accrued Liabilities and Other Liabilities | Observable Inputs (Level 2) |  |
Liabilities: |  |
Contingent purchase consideration liability | 0 | 0
Accounts Payable and Accrued Liabilities and Other Liabilities | Unobservable Inputs (Level 3) |  |
Liabilities: |  |
Contingent purchase consideration liability | $ 196 | $ 183

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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 No definition available. + Details
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