Variable Interest Entities and Securitizations - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Funded HELOCs advances	$ 30	$ 30
Unfunded commitment on residual interests on trusts	6	6
Maximum exposure to loss	4,782	4,451
Amortization Method Qualified Affordable Housing Project Investments, Amortization	337	305
Affordable Housing Tax Credits And Other Tax Benefits, Amount	382	336
Amortization Method Qualified Affordable Housing Project Investments	3,500	3,200
Qualified Affordable Housing Project Investments, Commitment	1,300
Carrying amounts of assets, unconsolidated	4,120	3,796
VIEs consolidated assets	$ 35,152	37,157
Minimum
Variable Interest Entity [Line Items]
Affordable Housing Tax Credits Commitment, Year to be Paid	2016
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	$ 3,852	3,500
Carrying amounts of assets, unconsolidated	3,852	3,500
Total assets of the unconsolidated VIE investment funds	11,400	10,200
VIEs consolidated assets	0	0
Entities that provide capital to low-income and rural communities
Variable Interest Entity [Line Items]
Maximum exposure to loss	0	1
Carrying amounts of assets, unconsolidated	0	1
VIEs consolidated assets	352	374
Other
Variable Interest Entity [Line Items]
Maximum exposure to loss	57	74
Carrying amounts of assets, unconsolidated	57	74
VIEs consolidated assets	0	4
Other VIE assets held in trust	120	159
Variable Interest Entity, Not Primary Beneficiary | Option- ARM
Variable Interest Entity [Line Items]
Securities held by third-party investors, mortgage	1,754	2,026
Unpaid principal balance of securitization trusts	1,814	2,094
Variable Interest Entity, Not Primary Beneficiary | GreenPoint HELOCs
Variable Interest Entity [Line Items]
Securities held by third-party investors, mortgage	74	95
Unpaid principal balance of securitization trusts	68	89
Variable Interest Entity, Not Primary Beneficiary | GreenPoint Manufactured Housing
Variable Interest Entity [Line Items]
Securities held by third-party investors, mortgage	789	887
Unpaid principal balance of securitization trusts	794	$ 893
Maximum exposure to loss	$ 420