Derivative Instruments and Hedging Activities - Net Gains (Losses) Recognized in Earnings Related to Derivatives in Fair Value Hedging Relationships and Free-Standing Derivatives (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	$ (8)	$ 3	$ (11)	$ (45)
Net derivative gains (losses) recognized in earnings	(15)	(17)	(40)	(73)
Other Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	(18)	(3)	(25)	(6)
Derivatives Designated as Accounting Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings on derivatives	3	16	(409)	95
Gains (losses) recognized in earnings on hedged items	(10)	(36)	380	(123)
Net fair value hedge ineffectiveness gains (losses)	(7)	(20)	(29)	(28)
Net derivative gains (losses) recognized in earnings	7	15	23	24
Derivatives not Designated as Accounting Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	10	11	18	(25)
Derivatives not Designated as Accounting Hedges [Member] | MSRs [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	0	1	(8)	4
Derivatives not Designated as Accounting Hedges [Member] | Customer Accommodation [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	6	11	31	29
Derivatives not Designated as Accounting Hedges [Member] | Other Interest Rate Exposures [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	4	(1)	(5)	(58)
Derivatives not Designated as Accounting Hedges [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as accounting hedges	$ 0	$ (5)	$ (4)	$ (14)