Activity Related to the MSR Portfolio (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Servicing Assets at Fair Value [Line Items]
Gain Loss On Sale Of Securities Net Economic Hedge Servicing Rights				$ 5
Changes Fair Value Of Free Standing Derivatives	38	129	42	102
Mortgage Servicing Rights (MSR) Impairment (Recovery)	$ (60)	$ (64)	$ (49)	$ (27)