Goodwill and Intangible Assets - Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 187	$ 213
Purchased credit card and affinity relationships
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	74	89
Core deposit intangibles
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	27	32
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	83	87
Other intangibles
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 3	$ 5