Activity Related to the MSR Portfolio (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Servicing Assets at Fair Value
Securities gains, net - non-qualifying hedges on MSRs	$ 6		$ 8
Changes in fair value and settlement of free-standing derivatives purchased to economically hedge the MSR portfolio (Mortgage banking net revenue)	(30)	38	(37)	42
Recovery of (provision for) MSR impairment (Mortgage banking net revenue)	$ 102	$ (60)	$ 151	$ (49)