Activity in the ALLL by segment (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 1,893	$ 2,040	$ 1,937	$ 2,044
Provision for loan losses	(28)	(76)	(84)	(182)
Allowance for Loan and Lease Losses, Write-offs	(123)	(158)	(254)	(309)
Loan recoveries	36	45	67	86
Balance at end of period	1,834	2,003	1,834	2,003
Commercial Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	976	966	986	946
Provision for loan losses	(33)	(18)	(40)	(57)
Allowance for Loan and Lease Losses, Write-offs	(31)	(38)	(59)	(71)
Loan recoveries	15	12	26	26
Balance at end of period	993	958	993	958
Residential Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	743	910	777	930
Provision for loan losses	(16)	(32)	(9)	(80)
Allowance for Loan and Lease Losses, Write-offs	(61)	(90)	(129)	(175)
Loan recoveries	10	23	19	40
Balance at end of period	676	875	676	875
Consumer Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	174	164	174	168
Provision for loan losses	(11)	(26)	(35)	(45)
Allowance for Loan and Lease Losses, Write-offs	(31)	(30)	(66)	(63)
Loan recoveries	11	10	22	20
Balance at end of period	$ 165	$ 170	$ 165	$ 170