Goodwill and Other Intangible Assets - Gross Carrying Amount, Accumulated Amortization And Net Carrying Amount Of Other Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,352	$ 3,300
Accumulated Amortization	(1,603)	(1,532)
Net Carrying Amount	1,749	1,768	$ 1,892	$ 2,025
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,523	2,486
Accumulated Amortization	(1,251)	(1,198)
Net Carrying Amount	1,272	1,288
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	676	667
Accumulated Amortization	(258)	(246)
Net Carrying Amount	418	421
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	153	147
Accumulated Amortization	(94)	(88)
Net Carrying Amount	$ 59	$ 59