Summary of Transactions in the ALLL by Portfolio segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Beginning Balance	$ 1,854	[1]	$ 2,255
Losses charged off	(168)		(253)
Recoveries of losses previously charged off	35		33
Provision for loan and lease losses	62		91
Ending Balance	1,783	[1]	2,126
Commercial Portfolio Segment
Beginning Balance	1,236	[2]	1,527
Losses charged off	(68)		(117)
Recoveries of losses previously charged off	14		15
Provision for loan and lease losses	9		(1)
Ending Balance	1,191	[2]	1,424
Residential Mortgage Loans
Beginning Balance	229	[2]	227
Losses charged off	(22)		(38)
Recoveries of losses previously charged off	2		1
Provision for loan and lease losses	3		43
Ending Balance	212	[2]	233
Consumer Portfolio Segment
Beginning Balance	278	[2]	365
Losses charged off	(78)		(98)
Recoveries of losses previously charged off	19		17
Provision for loan and lease losses	53		57
Ending Balance	272	[2]	341
Unallocated
Beginning Balance	111	[2]	136
Provision for loan and lease losses	(3)		(8)
Ending Balance	$ 108	[2]	$ 128

[1] Includes $50 and $50 of commercial mortgage loans, $(13) and $(5) of ALLL, $1 and $3 of other assets from consolidated VIEs that are included in their respective captions above at March 31, 2013 and December 31, 2012, respectively. See Note 8.

[2] Includes $11 related to leveraged leases.