Loans Held for Investment portfolio and Related Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Millions		Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Individually evaluated		$ 2,690		$ 2,781
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		269		319
Collectively evaluated		130,608		130,059
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		1,517		1,618
Total evaluated		133,298		132,840
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		1,786		1,937
Loans Receivable, Fair Value Disclosure		262		272
Total	[1]	133,560		133,112
Loans and Leases Receivable, Allowance		1,786	$ 1,834	1,937	$ 1,968	$ 2,003	$ 2,044
Commercial Portfolio Segment [Member]
Individually evaluated		70		92
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		7		11
Collectively evaluated		73,232		73,300
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		1,006		975
Total evaluated		73,302		73,392
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		1,013		986
Loans Receivable, Fair Value Disclosure		0		0
Total		73,302		73,392
Loans and Leases Receivable, Allowance		1,013	993	986	971	958	946
Residential Portfolio Segment [Member]
Individually evaluated		2,491		2,563
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		255		300
Collectively evaluated		36,035		35,940
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		346		477
Total evaluated		38,526		38,503
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		601		777
Loans Receivable, Fair Value Disclosure		262		272
Total		38,788		38,775
Loans and Leases Receivable, Allowance		601	676	777	817	875	930
Consumer Portfolio Segment [Member]
Individually evaluated		129		126
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		7		8
Collectively evaluated		21,341		20,819
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		165		166
Total evaluated		21,470		20,945
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		172		174
Loans Receivable, Fair Value Disclosure		0		0
Total		21,470		20,945
Loans and Leases Receivable, Allowance		$ 172	$ 165	$ 174	$ 180	$ 170	$ 168

[1] Includes loans of consolidated VIEs of $256 million and $288 million at September 30, 2015 and December 31, 2014, respectively.