Variable Interest Entities and Securitizations - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Funded HELOCs advances	$ 30	$ 30
Unfunded commitment on residual interests on trusts	5	6
Maximum exposure to loss	5,325	4,782
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	1,120	582
Amortization Method Qualified Affordable Housing Project Investments, Amortization	393	337
Affordable Housing Tax Credits And Other Tax Benefits, Amount	444	382
Amortization Method Qualified Affordable Housing Project Investments	3,800	3,500
Qualified Affordable Housing Project Investments, Commitment	1,200	1,300
Carrying amounts of assets, unconsolidated	4,250	4,120
VIEs consolidated assets	$ 34,651	35,152
Minimum
Variable Interest Entity [Line Items]
Affordable Housing Tax Credits Commitment, Year to be Paid	2017
Maximum
Variable Interest Entity [Line Items]
Affordable Housing Tax Credits Commitment, Year to be Paid	2019
Affordable housing entities
Variable Interest Entity [Line Items]
Maximum exposure to loss	$ 3,862	3,852
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	1,093	555
Carrying amounts of assets, unconsolidated	3,862	3,852
Total assets of the unconsolidated VIE investment funds	11,500	11,400
VIEs consolidated assets	174	0
Entities that provide capital to low-income and rural communities
Variable Interest Entity [Line Items]
Maximum exposure to loss	0	0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	0	0
Carrying amounts of assets, unconsolidated	0	0
VIEs consolidated assets	927	352
Other
Variable Interest Entity [Line Items]
Maximum exposure to loss	187	57
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	0	0
Carrying amounts of assets, unconsolidated	187	57
VIEs consolidated assets	0	0
GreenPoint Manufactured Housing
Variable Interest Entity [Line Items]
Maximum exposure to loss	420
Qualitative and Quantitative Information, Transferor's Continuing Involvement, Arrangements of Financial Support, Amount	12	13
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	8	8
Variable Interest Entity, Not Primary Beneficiary | Option- ARM
Variable Interest Entity [Line Items]
Securities held by third-party investors, mortgage	1,499	1,754
Continuing Involvement with Derecognized Transferred Financial Assets, Amount Outstanding	1,549	1,814
Variable Interest Entity, Not Primary Beneficiary | GreenPoint HELOCs
Variable Interest Entity [Line Items]
Securities held by third-party investors, mortgage	56	74
Continuing Involvement with Derecognized Transferred Financial Assets, Amount Outstanding	50	68
Variable Interest Entity, Not Primary Beneficiary | GreenPoint Manufactured Housing
Variable Interest Entity [Line Items]
Securities held by third-party investors, mortgage	697	789
Continuing Involvement with Derecognized Transferred Financial Assets, Amount Outstanding	702	794
Maximum exposure to loss	420
Letters of credit funded	$ 85	$ 76