Summary of Transactions in the ALLL by Portfolio segment (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	$ 1,582	[1],[2]	$ 1,854		$ 2,255
Losses charged off	(679)		(637)		(837)
Recoveries of losses previously charged off	104		136		133
Provision for loan and lease losses	315		229		303
Ending Balance	1,322	[1],[3]	1,582	[1],[2]	1,854
Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	1,058	[2]	1,236		1,527
Losses charged off	(299)		(284)		(358)
Recoveries of losses previously charged off	38		64		61
Provision for loan and lease losses	78		42		6
Ending Balance	875	[3]	1,058	[2]	1,236
Residential Mortgage Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	189	[2]	229		227
Losses charged off	(139)		(70)		(129)
Recoveries of losses previously charged off	13		10		7
Provision for loan and lease losses	41		20		124
Ending Balance	104	[3]	189	[2]	229
Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	225	[2]	278		365
Losses charged off	(241)		(283)		(350)
Recoveries of losses previously charged off	53		62		65
Provision for loan and lease losses	200		168		198
Ending Balance	237	[3]	225	[2]	278
Unallocated
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	110	[2]	111		136
Provision for loan and lease losses	(4)		(1)		(25)
Ending Balance	$ 106	[3]	$ 110	[2]	$ 111

[1] At December 31, 2014 and 2013, includes $179 and $49 of cash and due from banks, $47 and $48 of commercial mortgage loans, $3,331 and $1,010 of automobile loans, $(22) and $(15) of ALLL, $25 and $13 of other assets, $5 and $1 of other liabilities, $3,434 and $1,048 of long-term debt from consolidated VIEs that are included in their respective captions. For further information, refer to Note 10.

[2] Includes $9 related to leveraged leases.

[3] Includes $6 related to leveraged leases.