Activity in the Allowance for Credit Losses (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Components:
Allowance for credit losses		$ 1,840	$ 1,886	$ 1,840	$ 1,886	$ 1,831	$ 1,815	$ 1,947	$ 1,991
Provision for loan losses		141	28	243	84
Provision for Other Credit Losses		5	(2)	3	(2)
Allowance for Loan and Lease Losses, Write-offs		(167)	(123)	(278)	(254)
Loan recoveries		30	36	57	67
Loans and Leases Receivable, Allowance		1,774	1,834	1,774	1,834	$ 1,770	$ 1,752	$ 1,893	$ 1,937
Unfunded commitments reserve	[1]	$ 66	$ 52	$ 66	$ 52

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