Activity in the ALLL by segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 2,003	$ 2,125	$ 2,044	$ 2,174
Provision for loan losses	93	92	275	448
Allowance for Loan and Lease Losses, Write-offs	(164)	(189)	(473)	(695)
Loan recoveries	36	43	122	144
Balance at end of period	1,968	2,071	1,968	2,071
Commercial Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	958	919	946	902
Provision for loan losses	25	77	82	183
Allowance for Loan and Lease Losses, Write-offs	(26)	(52)	(97)	(176)
Loan recoveries	14	13	40	48
Balance at end of period	971	957	971	957
Residential Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	875	1,046	930	1,131
Provision for loan losses	34	(6)	114	184
Allowance for Loan and Lease Losses, Write-offs	(104)	(109)	(279)	(430)
Loan recoveries	12	21	52	67
Balance at end of period	817	952	817	952
Consumer Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	170	160	168	141
Provision for loan losses	34	21	79	81
Allowance for Loan and Lease Losses, Write-offs	(34)	(28)	(97)	(89)
Loan recoveries	10	9	30	29
Balance at end of period	180	162	180	162
Nonperforming Financing Receivable [Member] | Loans Held For Sale [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Residential Mortgages Transferred To Held For Sale, Net Of Impairment	$ 53		$ 53	$ 22