Loans Held for Investment portfolio and Related Allowance for Loan and Lease Losses (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Jun. 30, 2012	Dec. 31, 2011		Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Individually evaluated	$ 3,094			$ 3,592
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	344			448
Collectively evaluated	118,333			118,470
Total evaluated	121,427			122,062
Loans carried at fair value	390	[1]		433	[1]
Total	121,817	[1]		122,495	[1]
Individually evaluated	344			448
Collectively evaluated	1,895			2,009
Total evaluated	2,239			2,457
Total LHFI	2,239		2,300	2,457		2,600	2,744	2,974
Commercial Portfolio Segment [Member]
Individually evaluated	218			412
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	8			34
Collectively evaluated	57,488			55,458
Total evaluated	57,706			55,870
Loans carried at fair value	0			2
Total	57,706			55,872
Individually evaluated	8			34
Collectively evaluated	935			930
Total evaluated	943			964
Total LHFI	943		887	964		1,101	1,200	1,303
Residential Portfolio Segment [Member]
Individually evaluated	2,810			3,141
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	328			405
Collectively evaluated	41,372			43,088
Total evaluated	44,182			46,229
Loans carried at fair value	390			431
Total	44,572			46,660
Individually evaluated	328			405
Collectively evaluated	834			949
Total evaluated	1,162			1,354
Total LHFI	1,162		1,277	1,354		1,352	1,395	1,498
Consumer Portfolio Segment [Member]
Individually evaluated	66			39
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	8			9
Collectively evaluated	19,473			19,924
Total evaluated	19,539			19,963
Loans carried at fair value	0			0
Total	19,539			19,963
Individually evaluated	8			9
Collectively evaluated	126			130
Total evaluated	134			139
Total LHFI	$ 134		$ 136	$ 139		$ 147	$ 149	$ 173

[1] 2 Includes loans of consolidated VIEs374 3,322