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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, 2018 | Dec. 31, 2017
--- | --- | ---
Financial instruments owned: |  |  |
Total assets measured at fair value |  | $ 276 | $ 382
Fiduciary Assets: |  |  |
Fiduciary assets |  | 129 | 111
Liabilities: |  |  |
Total liabilities measured at fair value |  | 185 | 189
Identical Assets (Level 1) |  |  |
Financial instruments owned: |  |  |
Total assets measured at fair value |  | 276 | 382
Fiduciary Assets: |  |  |
Fiduciary assets |  | 129 | 111
Liabilities: |  |  |
Total liabilities measured at fair value |  | 0 | 0
Observable Inputs (Level 2) |  |  |
Financial instruments owned: |  |  |
Total assets measured at fair value |  | 0 | 0
Fiduciary Assets: |  |  |
Fiduciary assets |  | 0 | 0
Liabilities: |  |  |
Total liabilities measured at fair value |  | 0 | 0
Unobservable Inputs (Level 3) |  |  |
Financial instruments owned: |  |  |
Total assets measured at fair value |  | 0 | 0
Fiduciary Assets: |  |  |
Fiduciary assets |  | 0 | 0
Liabilities: |  |  |
Total liabilities measured at fair value |  | 185 | 189
Money Market Funds |  |  |
Fiduciary Assets: |  |  |
Fiduciary assets |  | 129 | 111
Money Market Funds | Identical Assets (Level 1) |  |  |
Fiduciary Assets: |  |  |
Fiduciary assets |  | 129 | 111
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
Other Assets |  |  |
Financial instruments owned: |  |  |
Exchange traded equity securities | [1] | 99 | 81
Mutual funds | [1] | 144 | 158
Other Assets | Identical Assets (Level 1) |  |  |
Financial instruments owned: |  |  |
Exchange traded equity securities | [1] | 99 | 81
Mutual funds | [1] | 144 | 158
Other Assets | Observable Inputs (Level 2) |  |  |
Financial instruments owned: |  |  |
Exchange traded equity securities | [1] | 0 | 0
Mutual funds | [1] | 0 | 0
Other Assets | Unobservable Inputs (Level 3) |  |  |
Financial instruments owned: |  |  |
Exchange traded equity securities | [1] | 0 | 0
Mutual funds | [1] | 0 | 0
Cash and Cash Equivalents |  |  |
Financial instruments owned: |  |  |
Money market funds | [2] | 33 | 143
Cash and Cash Equivalents | Identical Assets (Level 1) |  |  |
Financial instruments owned: |  |  |
Money market funds | [2] | 33 | 143
Cash and Cash Equivalents | Observable Inputs (Level 2) |  |  |
Financial instruments owned: |  |  |
Money market funds | [2] | 0 | 0
Cash and Cash Equivalents | Unobservable Inputs (Level 3) |  |  |
Financial instruments owned: |  |  |
Money market funds | [2] | 0 | 0
Accounts Payable and Accrued Liabilities and Other Liabilities |  |  |
Liabilities: |  |  |
Contingent purchase consideration liability | [3] | 185 | 189
Accounts Payable and Accrued Liabilities and Other Liabilities | Identical Assets (Level 1) |  |  |
Liabilities: |  |  |
Contingent purchase consideration liability | [3] | 0 | 0
Accounts Payable and Accrued Liabilities and Other Liabilities | Observable Inputs (Level 2) |  |  |
Liabilities: |  |  |
Contingent purchase consideration liability | [3] | 0 | 0
Accounts Payable and Accrued Liabilities and Other Liabilities | Unobservable Inputs (Level 3) |  |  |
Liabilities: |  |  |
Contingent purchase consideration liability | [3] | $ 185 | $ 189
[1] | Included in other assets in the consolidated balance sheets.
[2] | Included in cash and cash equivalents in the consolidated balance sheets.
[3] | Included in accounts payable and accrued liabilities and other liabilities in the consolidated balance sheets.

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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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