Goodwill and Other Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Intangible Assets
Amortization Expense	$ 40	$ 53	$ 65
Gross Carrying Amount	776	768
Accumulated Amortization	(570)	(528)
Net Carrying Amount	206	240
Core deposit intangibles
Intangible Assets
Gross Carrying Amount	565	565
Accumulated Amortization	(497)	(468)
Net Carrying Amount	68	97
Trade names
Intangible Assets
Gross Carrying Amount	114	114
Accumulated Amortization	(24)	(21)
Net Carrying Amount	90	93
Customer Relationships
Intangible Assets
Gross Carrying Amount	57	60
Accumulated Amortization	(30)	(25)
Net Carrying Amount	27	35
Other intangibles assets
Intangible Assets
Gross Carrying Amount	40	29
Accumulated Amortization	(19)	(14)
Net Carrying Amount	$ 21	$ 15