Activity in the Allowance for Credit Losses (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Components:
Balance at beginning of period	$ 2,505		$ 3,032		$ 3,235
Provision for loan losses	1,398		1,523		2,708
Allowance for Loan and Lease Losses, Loans Consolidated	0		0		1
Provision(Benefit) for unfunded commitments	3		10		57
Loan charge-offs	(1,907)		(2,241)		(3,018)
Loan recoveries	226		201		163
Balance at end of period	2,219		2,505		3,032
ALLL	2,174		2,457		2,974
Unfunded commitments reserve	45	[1]	48	[1]	58	[1]
Allowance for credit losses	$ 2,219		$ 2,505		$ 3,032

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