Goodwill and Other Intangibles (Amortized Intangible Assets) (Details) - USD ($) $ in Millions		Mar. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Cost		$ 1,796	$ 1,594
Accumulated Amortization		505	468
Net Carrying Amount		1,291	1,126
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross Cost		1,591	1,390
Accumulated Amortization		422	392
Net Carrying Amount		1,169	998
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Gross Cost	[1]	205	204
Accumulated Amortization	[1]	83	76
Net Carrying Amount	[1]	$ 122	$ 128

[1] Primarily non-compete agreements, trade names and developed technology.