Activity in the Allowance for Credit Losses (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		Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Components:
Balance at beginning of period	$ 2,205		$ 2,400		$ 2,219		$ 2,505
Provision for loan losses	152		302		356		615
Provision(Benefit) for unfunded commitments	6		2		(2)		(2)
Loan charge-offs	(233)		(397)		(506)		(860)
Loan recoveries	54		47		101		(88)
Balance at end of period	2,172		2,350		2,172		2,350
Loans and Leases Receivable, Allowance	2,125		2,300		2,125		2,300		2,152	2,174	2,348	2,457
Unfunded commitments reserve	47	[1]	50	[1]	47	[1]	50	[1]
Allowance for credit losses	$ 2,172		$ 2,350		$ 2,172		$ 2,350

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