Activity in the ALLL by segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 1,937	$ 2,044
Provision for loan losses	55	106
Allowance for Loan and Lease Losses, Write-offs	(130)	(151)
Loan recoveries	31	41
Balance at end of period	1,893	2,040
Commercial Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	986	946
Provision for loan losses	7	39
Allowance for Loan and Lease Losses, Write-offs	(28)	(33)
Loan recoveries	11	14
Balance at end of period	976	966
Residential Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	777	930
Provision for loan losses	25	48
Allowance for Loan and Lease Losses, Write-offs	(68)	(85)
Loan recoveries	9	17
Balance at end of period	743	910
Consumer Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	174	168
Provision for loan losses	23	19
Allowance for Loan and Lease Losses, Write-offs	(34)	(33)
Loan recoveries	11	10
Balance at end of period	$ 174	$ 164