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, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gains (losses) recognized in earnings	$ 27	$ (15)	$ 74	$ (40)
Derivatives designated as accounting hedges | Fair value hedges | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
(Losses) gains recognized in earnings on derivatives	(94)	3	42	(409)
Gains (losses) recognized in earnings on hedged items	110	(10)	(5)	380
Net fair value hedge ineffectiveness gains (losses)	16	(7)	37	(29)
Derivatives not designated as accounting hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	11	(8)	37	(11)
Derivatives not designated as accounting hedges | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	13	10	37	18
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	1	0	14	(8)
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	7	6	15	31
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	5	4	8	(5)
Derivatives not designated as accounting hedges | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	0	0	1	(4)
Derivatives not designated as accounting hedges | Other contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	$ (2)	$ (18)	$ (1)	$ (25)