Certain Transfers of Financial Assets and Variable Interest Entities - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017	Dec. 31, 2017
Assets		$ 204,885			$ 205,962
Total liabilities		180,616			180,808
Long-term Debt	[1]	10,692			9,785
Derivative Asset, Notional Amount		129,913	[2]		143,238
Trading Securities	[3]	5,112			5,093
Other Assets	[4]	8,279			9,418
Affordable Housing Tax Credits and Other Tax Benefits, Amount		30		$ 25
Amortization Method Qualified Affordable Housing Project Investments, Amortization		32		24
Amortization of Intangible Assets	[5]	5		5
Amortization		15		13
Variable Interest Entity, Not Primary Beneficiary [Member] | Community Development Investments [Member]
Investment Tax Credit		18		17
Amortization of Intangible Assets		14		12
Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt		182			189
Residential Mortgage [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Loans and Leases Receivable, Gain (Loss) on Sales, Net		13		4
Transferor's Interests in Transferred Financial Assets, Fair Value		21			22
Assets		142			147
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		21			22
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Loans and Leases Receivable, Gain (Loss) on Sales, Net		9		$ 11
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Loans Receivable, Net		185			192
Long-term Debt		$ 182			$ 189
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Government Guarantee Percent		98.00%			98.00%
Total Return Swap [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Derivative Asset, Notional Amount		$ 1,700			$ 1,700
Trading Securities		1,700			1,700
Community Development Investments [Member]
Other Assets	[6]	1,383			1,331
Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Assets		2,300			2,300
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		665			643
Real Estate Variable Interest Entity Borrowings		317			278
Limited Partner [Member] | Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Other Assets	[6]	1,066			1,053
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		1,373			1,391
Loans Issued by the Company to the Limited Partnerships		$ 344			$ 350
Death, Disability, Bankruptcy [Member] | Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Government Guarantee Percent		100.00%

[1] Includes debt of consolidated VIEs of $182 million and $189 million at March 31, 2018 and December 31, 2017, respectively.

[2] For centrally-cleared derivatives, notional amounts are presented based on the fair value of the related derivative asset or derivative liability after applying variation margin.

[3] Includes trading securities pledged as collateral where counterparties have the right to sell or repledge the collateral of $1,248 million and $1,086 million at March 31, 2018 and December 31, 2017, respectively.

[4] Text selection found with no content.

[5] Does not include expense associated with non-qualified community development investments. See Note 10, "Certain Transfers of Financial Assets and Variable Interest Entities," for additional information.

[6] See Note 10, "Certain Transfers of Financial Assets and Variable Interest Entities," for additional information.