Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Financial instruments owned:
Total assets measured at fair value		$ 446	$ 257
Fiduciary Assets:
Fiduciary assets		79	57
Liabilities:
Total liabilities measured at fair value		283	207
Identical Assets (Level 1) [Member]
Financial instruments owned:
Total assets measured at fair value		446	257
Fiduciary Assets:
Fiduciary assets		79	57
Liabilities:
Total liabilities measured at fair value		0	0
Observable Inputs (Level 2) [Member]
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) [Member]
Financial instruments owned:
Total assets measured at fair value		0	0
Fiduciary Assets:
Fiduciary assets		0	0
Liabilities:
Total liabilities measured at fair value		283	207
Money Market Funds [Member]
Fiduciary Assets:
Fiduciary assets		79	57
Money Market Funds [Member] | Identical Assets (Level 1) [Member]
Fiduciary Assets:
Fiduciary assets		79	57
Money Market Funds [Member] | Observable Inputs (Level 2) [Member]
Fiduciary Assets:
Fiduciary assets		0	0
Money Market Funds [Member] | Unobservable Inputs (Level 3) [Member]
Fiduciary Assets:
Fiduciary assets		0	0
Other Assets [Member]
Financial instruments owned:
Mutual funds	[1]	136	150
Other Assets [Member] | Identical Assets (Level 1) [Member]
Financial instruments owned:
Mutual funds	[1]	136	150
Other Assets [Member] | Observable Inputs (Level 2) [Member]
Financial instruments owned:
Mutual funds	[1]	0	0
Other Assets [Member] | Unobservable Inputs (Level 3) [Member]
Financial instruments owned:
Mutual funds	[1]	0	0
Cash and Cash Equivalents [Member]
Financial instruments owned:
Money market funds	[2]	310	107
Cash and Cash Equivalents [Member] | Identical Assets (Level 1) [Member]
Financial instruments owned:
Money market funds	[2]	310	107
Cash and Cash Equivalents [Member] | Observable Inputs (Level 2) [Member]
Financial instruments owned:
Money market funds	[2]	0	0
Cash and Cash Equivalents [Member] | Unobservable Inputs (Level 3) [Member]
Financial instruments owned:
Money market funds	[2]	0	0
Accounts Payable and Accrued Liabilities and Other Liabilities [Member]
Liabilities:
Contingent purchase consideration liability	[3]	283	207
Accounts Payable and Accrued Liabilities and Other Liabilities [Member] | Identical Assets (Level 1) [Member]
Liabilities:
Contingent purchase consideration liability	[3]	0	0
Accounts Payable and Accrued Liabilities and Other Liabilities [Member] | Observable Inputs (Level 2) [Member]
Liabilities:
Contingent purchase consideration liability	[3]	0	0
Accounts Payable and Accrued Liabilities and Other Liabilities [Member] | Unobservable Inputs (Level 3) [Member]
Liabilities:
Contingent purchase consideration liability	[3]	$ 283	$ 207

[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.