Activity in the Allowance for Credit Losses (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013
Components:
Balance at beginning of period		$ 1,947	$ 2,086	$ 1,991	$ 2,094
Provision for loan losses		28	76	84	182
Provision(Benefit) for unfunded commitments		(2)	(3)	(2)	(7)
Allowance for Loan and Lease Losses, Write-offs		(123)	(158)	(254)	(309)
Loan recoveries		36	45	67	86
Balance at end of period		1,886	2,046	1,886	2,046
Loans and Leases Receivable, Allowance						$ 1,834	$ 1,893	$ 1,937	$ 2,003	$ 2,040	$ 2,044
Unfunded commitments reserve	[1]					52			43
Allowance for credit losses		$ 1,947	$ 2,086	$ 1,991	$ 2,094	$ 1,886	$ 1,947	$ 1,991	$ 2,046	$ 2,086	$ 2,094

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