Loans Held for Investment portfolio and Related Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Individually evaluated		$ 3,068	$ 2,876
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		255	287
Collectively evaluated		140,008	133,309
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		1,454	1,465
Total evaluated		143,076	136,185
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		1,709	1,752
Loans Receivable, Fair Value Disclosure		222	257
Total	[1]	143,298	136,442
Loans and Leases Receivable, Allowance		1,709	1,752	$ 1,937
Commercial Portfolio Segment [Member]
Individually evaluated		382	218
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		33	28
Collectively evaluated		77,842	75,034
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		1,091	1,019
Total evaluated		78,224	75,252
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		1,124	1,047
Loans Receivable, Fair Value Disclosure		0	0
Total		78,224	75,252
Loans and Leases Receivable, Allowance		1,124	1,047	986
Residential Portfolio Segment [Member]
Individually evaluated		2,518	2,527
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		215	252
Collectively evaluated		36,250	36,144
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		154	282
Total evaluated		38,768	38,671
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		369	534
Loans Receivable, Fair Value Disclosure		222	257
Total		38,990	38,928
Loans and Leases Receivable, Allowance		369	534	777
Consumer Portfolio Segment [Member]
Individually evaluated		168	131
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		7	7
Collectively evaluated		25,916	22,131
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment		209	164
Total evaluated		26,084	22,262
Loans And Leases Receivable Allowance Loans Evaluated For Impairment Excluding Fair Value Loans		216	171
Loans Receivable, Fair Value Disclosure		0	0
Total		26,084	22,262
Loans and Leases Receivable, Allowance		$ 216	$ 171	$ 174

[1] Includes loans of consolidated VIEs of $211 million and $246 million at December 31, 2016 and December 31, 2015, respectively.