Summary of Transactions in the ALLL by Portfolio segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Beginning Balance	$ 2,126		$ 2,805		$ 2,255	[1]	$ 3,004
Losses charged off	(219)		(343)		(472)		(740)
Recoveries of losses previously charged off	38		39		71		69
Provision for loan and lease losses	71		113		162		281
Ending Balance	2,016	[1]	2,614	[1]	2,016	[1]	2,614	[1]
Commercial Portfolio Segment
Beginning Balance	1,424		1,855		1,527	[2]	1,989
Losses charged off	(95)		(158)		(211)		(334)
Recoveries of losses previously charged off	17		17		33		29
Provision for loan and lease losses	1		50		(2)		80
Ending Balance	1,347	[3]	1,764	[4]	1,347	[3]	1,764	[4]
Residential Mortgage Loans
Beginning Balance	233		286		227	[2]	310
Losses charged off	(38)		(37)		(76)		(104)
Recoveries of losses previously charged off	2		1		3		3
Provision for loan and lease losses	35		18		78		59
Ending Balance	232	[3]	268	[4]	232	[3]	268	[4]
Consumer Portfolio Segment
Beginning Balance	341		519		365	[2]	555
Losses charged off	(86)		(148)		(185)		(302)
Recoveries of losses previously charged off	19		21		35		37
Provision for loan and lease losses	42		60		101		162
Ending Balance	316	[3]	452	[4]	316	[3]	452	[4]
Unallocated (Member)
Beginning Balance	128		145		136	[2]	150
Provision for loan and lease losses	(7)		(15)		(15)		(20)
Ending Balance	$ 121	[3]	$ 130	[4]	$ 121	[3]	$ 130	[4]

[1] Includes $9, $30 and $42 of cash, $4, $7 and $7of other short-term investments, $51, $50 and $29 of commercial mortgage loans, $0, $223 and $231 of home equity loans, $75, $259 and $424 of automobile loans, ($3), ($10) and ($11) of ALLL, $3, $4 and $4 of other assets, $2, $4 and $8 of other liabilities, $73, $191and $365 of long-term debt from consolidated VIEs that are included in their respective captions above at June 30, 2012, December 31, 2011 and June 30, 2011, respectively. See Note 8.

[2] Includes $14 related to leveraged leases.

[3] Includes $15 related to leveraged leases.

[4] Includes $18 related to leveraged leases.