Variable Interest Entities and Securitizations - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Variable Interest Entity [Line Items]
Funded HELOCs advances	$ 30		$ 30
Unfunded commitment on residual interests on trusts	6		6
Maximum exposure to loss	4,854		4,782
Amortization Method Qualified Affordable Housing Project Investments, Amortization	98	$ 86
Affordable Housing Tax Credits And Other Tax Benefits, Amount	113	$ 102
Amortization Method Qualified Affordable Housing Project Investments	3,600		3,500
Qualified Affordable Housing Project Investments, Commitment	1,300
Carrying amounts of assets, unconsolidated	4,192		4,120
VIEs consolidated assets	$ 33,671		35,152
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	$ 3,804		3,852
Carrying amounts of assets, unconsolidated	3,804		3,852
Total assets of the unconsolidated VIE investment funds	11,300		11,400
VIEs consolidated assets	115		0
Entities that provide capital to low-income and rural communities
Variable Interest Entity [Line Items]
Maximum exposure to loss	71		0
Carrying amounts of assets, unconsolidated	71		0
VIEs consolidated assets	687		352
Other
Variable Interest Entity [Line Items]
Maximum exposure to loss	116		57
Carrying amounts of assets, unconsolidated	116		57
VIEs consolidated assets	0		0
Variable Interest Entity, Not Primary Beneficiary | Option- ARM
Variable Interest Entity [Line Items]
Securities held by third-party investors, mortgage	1,692		1,754
Unpaid principal balance of securitization trusts	1,749		1,814
Variable Interest Entity, Not Primary Beneficiary | GreenPoint HELOCs
Variable Interest Entity [Line Items]
Securities held by third-party investors, mortgage	69		74
Unpaid principal balance of securitization trusts	63		68
Variable Interest Entity, Not Primary Beneficiary | GreenPoint Manufactured Housing
Variable Interest Entity [Line Items]
Securities held by third-party investors, mortgage	765		789
Unpaid principal balance of securitization trusts	771		$ 794
Maximum exposure to loss	$ 420