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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gains recognized in earnings	$ 29	$ 29	$ 40	$ 75
Derivatives designated as accounting hedges | Fair value hedges | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains recognized in earnings on derivatives	138	182	93	390
Losses recognized in earnings on hedged items	(132)	(175)	(93)	(367)
Net fair value hedge ineffectiveness gains (losses)	6	7	0	23
Derivatives not designated as accounting hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	23	22	40	52
Derivatives not designated as accounting hedges | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	23	31	40	61
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	3	8	3	18
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	6	7	16	12
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	14	16	21	31
Derivatives not designated as accounting hedges | Other contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	$ 0	$ (9)	$ 0	$ (9)