Loans Held for Investment portfolio and Related Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Individually evaluated		$ 3,207	$ 2,876
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		283	287
Collectively evaluated		136,284	133,309
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		1,487	1,465
Total evaluated		139,491	136,185
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		1,770	1,752
Loans Receivable, Fair Value Disclosure		255	257
Total	[1]	139,746	136,442
Loans and Leases Receivable, Allowance		1,770	1,752	$ 1,893	$ 1,937
Commercial Portfolio Segment [Member]
Individually evaluated		521	218
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		34	28
Collectively evaluated		76,974	75,034
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		1,089	1,019
Total evaluated		77,495	75,252
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		1,123	1,047
Loans Receivable, Fair Value Disclosure		0	0
Total		77,495	75,252
Loans and Leases Receivable, Allowance		1,123	1,047	976	986
Residential Portfolio Segment [Member]
Individually evaluated		2,555	2,527
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		242	252
Collectively evaluated		36,189	36,144
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		225	282
Total evaluated		38,744	38,671
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		467	534
Loans Receivable, Fair Value Disclosure		255	257
Total		38,999	38,928
Loans and Leases Receivable, Allowance		467	534	743	777
Consumer Portfolio Segment [Member]
Individually evaluated		131	131
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		7	7
Collectively evaluated		23,121	22,131
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		173	164
Total evaluated		23,252	22,262
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		180	171
Loans Receivable, Fair Value Disclosure		0	0
Total		23,252	22,262
Loans and Leases Receivable, Allowance		$ 180	$ 171	$ 174	$ 174

[1] Includes loans of consolidated VIEs of $237 million and $246 million at March 31, 2016 and December 31, 2015, respectively.