Activity in the ALLL by segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 2,348	$ 2,854	$ 2,457	$ 2,974
Provision for loan losses	302	395	615	846
Loan charge-offs	(397)	(563)	(860)	(1,178)
Loan recoveries	47	58	88	102
Balance at end of period	2,300	2,744	2,300	2,744
Commercial Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	901	1,255	964	1,303
Provision for loan losses	49	124	87	232
Loan charge-offs	(94)	(220)	(220)	(405)
Loan recoveries	31	41	56	70
Balance at end of period	887	1,200	887	1,200
Residential Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	1,315	1,440	1,354	1,498
Provision for loan losses	230	252	488	574
Loan charge-offs	(274)	(303)	(576)	(688)
Loan recoveries	6	6	11	11
Balance at end of period	1,277	1,395	1,277	1,395
Consumer Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	132	159	139	173
Provision for loan losses	23	19	40	40
Loan charge-offs	(29)	(40)	(64)	(85)
Loan recoveries	10	11	21	21
Balance at end of period	$ 136	$ 149	$ 136	$ 149