Activity in the ALLL by segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 2,044	$ 2,174
Provision for loan losses	106	204
Loan charge-offs	(151)	(273)
Loan recoveries	41	47
Balance at end of period	2,040	2,152
Commercial Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	946	902
Provision for loan losses	39	64
Loan charge-offs	(33)	(60)
Loan recoveries	14	15
Balance at end of period	966	921
Residential Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	930	1,131
Provision for loan losses	48	112
Loan charge-offs	(85)	(178)
Loan recoveries	17	22
Balance at end of period	910	1,087
Consumer Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	168	141
Provision for loan losses	19	28
Loan charge-offs	(33)	(35)
Loan recoveries	10	10
Balance at end of period	$ 164	$ 144