Derivative Instruments and Hedging Activities - Net Gains (Losses) Recognized in Earnings Related to Derivatives in Fair Value Hedging Relationships and Free-Standing Derivatives (Details) - Other Non-Interest Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gains recognized in earnings	$ 46	$ 15
Derivatives designated as accounting hedges | Fair value hedges | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings on derivatives	208	153
Gains (losses) recognized in earnings on hedged items	(192)	(148)
Net fair value hedge ineffectiveness gains (losses)	16	5
Derivatives not designated as accounting hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	30	10
Derivatives not designated as accounting hedges | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	30	12
Derivatives not designated as accounting hedges | Interest rate contracts | MSRs
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	10	6
Derivatives not designated as accounting hedges | Interest rate contracts | Customer accommodation
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	5	4
Derivatives not designated as accounting hedges | Interest rate contracts | Other interest rate exposures
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	15	2
Derivatives not designated as accounting hedges | Other contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	$ 0	$ (2)