Loans Held for Investment portfolio and Related Allowance for Loan and Lease Losses (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Jun. 30, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Individually evaluated	$ 2,868			$ 3,159
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	328			363
Collectively evaluated	128,999			124,416
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,640			1,681
Total evaluated	131,867			127,575
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans	1,968			2,044
Loans Receivable, Fair Value Disclosure	284			302
Total	132,151	[1]		127,877	[1]
Loans and Leases Receivable, Allowance	1,968		2,003	2,044		2,071	2,125	2,174
Commercial Portfolio Segment [Member]
Individually evaluated	129			171
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	8			10
Collectively evaluated	70,965			64,139
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	963			936
Total evaluated	71,094			64,310
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans	971			946
Loans Receivable, Fair Value Disclosure	0			0
Total	71,094			64,310
Loans and Leases Receivable, Allowance	971		958	946		957	919	902
Residential Portfolio Segment [Member]
Individually evaluated	2,616			2,878
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	313			345
Collectively evaluated	36,322			40,010
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	504			585
Total evaluated	38,938			42,888
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans	817			930
Loans Receivable, Fair Value Disclosure	284			302
Total	39,222			43,190
Loans and Leases Receivable, Allowance	817		875	930		952	1,046	1,131
Consumer Portfolio Segment [Member]
Individually evaluated	123			110
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	7			8
Collectively evaluated	21,712			20,267
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	173			160
Total evaluated	21,835			20,377
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans	180			168
Loans Receivable, Fair Value Disclosure	0			0
Total	21,835			20,377
Loans and Leases Receivable, Allowance	$ 180		$ 170	$ 168		$ 162	$ 160	$ 141

[1] Includes loans of consolidated VIEs of $298 million and $327 million at September 30, 2014 and December 31, 2013, respectively.