Activity in the Allowance for Credit Losses (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		Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Components:
Balance at beginning of period	$ 2,400		$ 2,908		$ 2,505		$ 3,032
Provision for loan losses	302		395		615		846
Provision(Benefit) for unfunded commitments	(2)		(3)		2		(7)
Loan charge-offs	(397)		(563)		(860)		(1,178)
Loan recoveries	47		58		88		102
Balance at end of period	2,350		2,795		2,350		2,795
ALLL	2,300		2,744		2,300		2,744		2,348	2,457	2,854	2,974
Unfunded commitments reserve	50	[1]	51	[1]	50	[1]	51	[1]
Allowance for credit losses	$ 2,350		$ 2,795		$ 2,350		$ 2,795

[1] The unfunded commitments reserve is recorded in other liabilities in the Consolidated Balance Sheets.