Changes in the Servicing Asset Related to Residential Mortgage Loans (Detail) (Residential Mortgage, USD $) In Millions	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Residential Mortgage
Servicing Assets at Fair Value [Line Items]
Carrying amount as of the beginning of the period	$ 1,138	$ 979
Servicing obligations that result from the transfer of residential mortgage loans	105	101
Amortization	(53)	(48)
Carrying amount before valuation allowance	1,190	1,032
Valuation allowance for servicing assets:
Beginning balance	(316)	(280)
Servicing impairment	(27)	(106)
Ending balance	(343)	(386)
Carrying amount as of the end of the period	$ 847	$ 646