Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Financial instruments owned:
Total assets measured at fair value	$ 176		$ 257
Fiduciary Assets:
Fiduciary assets	95		57
Liabilities:
Total liabilities measured at fair value	206		207
Identical Assets (Level 1) [Member]
Financial instruments owned:
Total assets measured at fair value	176		257
Fiduciary Assets:
Fiduciary assets	95		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	206		207
Money Market Funds [Member]
Fiduciary Assets:
Fiduciary assets	95		57
Money Market Funds [Member] | Identical Assets (Level 1) [Member]
Fiduciary Assets:
Fiduciary assets	95		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	140	[1]	150	[1]
Other Assets [Member] | Identical Assets (Level 1) [Member]
Financial instruments owned:
Mutual funds	140	[1]	150	[1]
Other Assets [Member] | Observable Inputs (Level 2) [Member]
Financial instruments owned:
Mutual funds	0	[1]	0	[1]
Other Assets [Member] | Unobservable Inputs (Level 3) [Member]
Financial instruments owned:
Mutual funds	0	[1]	0	[1]
Cash and Cash Equivalents [Member]
Financial instruments owned:
Money market funds	36	[2]	107	[2]
Cash and Cash Equivalents [Member] | Identical Assets (Level 1) [Member]
Financial instruments owned:
Money market funds	36	[2]	107	[2]
Cash and Cash Equivalents [Member] | Observable Inputs (Level 2) [Member]
Financial instruments owned:
Money market funds	0	[2]	0	[2]
Cash and Cash Equivalents [Member] | Unobservable Inputs (Level 3) [Member]
Financial instruments owned:
Money market funds	0	[2]	0	[2]
Accounts Payable and Accrued Liabilities and Other Liabilities [Member]
Liabilities:
Contingent purchase consideration liability	206	[3]	207	[3]
Accounts Payable and Accrued Liabilities and Other Liabilities [Member] | Identical Assets (Level 1) [Member]
Liabilities:
Contingent purchase consideration liability	0	[3]	0	[3]
Accounts Payable and Accrued Liabilities and Other Liabilities [Member] | Observable Inputs (Level 2) [Member]
Liabilities:
Contingent purchase consideration liability	0	[3]	0	[3]
Accounts Payable and Accrued Liabilities and Other Liabilities [Member] | Unobservable Inputs (Level 3) [Member]
Liabilities:
Contingent purchase consideration liability	$ 206	[3]	$ 207	[3]

[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.