Goodwill and Other Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Intangible Assets
Amortization Expense	$ 28	$ 42	$ 52
Gross Carrying Amount	837	776
Accumulated Amortization	(591)	(570)
Net Carrying Amount	246	206
Core deposit intangibles
Intangible Assets
Gross Carrying Amount	565	565
Accumulated Amortization	(516)	(497)
Net Carrying Amount	49	68
Trade names
Intangible Assets
Gross Carrying Amount	113	114
Accumulated Amortization	(26)	(24)
Net Carrying Amount	87	90
Customer Relationships
Intangible Assets
Gross Carrying Amount	118	57
Accumulated Amortization	(34)	(30)
Net Carrying Amount	84	27
Other intangibles assets
Intangible Assets
Gross Carrying Amount	41	40
Accumulated Amortization	(15)	(19)
Net Carrying Amount	$ 26	$ 21