Goodwill and Other Intangible Assets - Gross Carrying Amount, Accumulated Amortization And Net Carrying Amount Of Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,413	$ 3,300
Accumulated Amortization	(1,663)	(1,532)
Net Carrying Amount	1,750	1,768	$ 2,025
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,620	2,486
Accumulated Amortization	(1,306)	(1,198)
Net Carrying Amount	1,314	1,288
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	661	667
Accumulated Amortization	(277)	(246)
Net Carrying Amount	384	421
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	132	147
Accumulated Amortization	(80)	(88)
Net Carrying Amount	$ 52	$ 59
Minimum | Client relationships
Finite-Lived Intangible Assets [Line Items]
Useful life	5 years
Minimum | Core deposits
Finite-Lived Intangible Assets [Line Items]
Useful life	16 years
Maximum | Client relationships
Finite-Lived Intangible Assets [Line Items]
Useful life	20 years
Maximum | Core deposits
Finite-Lived Intangible Assets [Line Items]
Useful life	22 years