Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Amortization of other intangible assets	$ 197	$ 222	$ 214
Impairment of intangible assets, excluding goodwill		$ 9
Other | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets	5 years
Other | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets	20 years
Core deposits | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets	16 years
Core deposits | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets	22 years