Certain Transfers of Financial Assets and Variable Interest Entities - Additional Information (Detail) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 01, 2015	Dec. 31, 2014
Cash Flows Between Transferor and Transferee, Receipts on Transferor's Interest in Transferred Financial Assets, Other		$ 6,000,000	$ 2,000,000	$ 14,000,000	$ 14,000,000
Long-term Debt	[1]	8,444,000,000		8,444,000,000			$ 13,022,000,000
Total liabilities		163,372,000,000		163,372,000,000			167,323,000,000
Assets		187,036,000,000		187,036,000,000			190,328,000,000
LHFS excluded from managed loans disclosure		2,000,000,000		2,000,000,000			3,200,000,000
Trading assets	[2]	6,537,000,000		6,537,000,000			6,202,000,000
Derivative Asset, Fair Value, Gross Asset		5,258,000,000		5,258,000,000			5,839,000,000
Derivative Liability, Fair Value, Gross Liability		4,930,000,000		4,930,000,000			5,577,000,000
Other Assets		5,458,000,000		5,458,000,000			5,656,000,000
Affordable Housing Tax Credits and Other Tax Benefits, Amount		18,000,000	15,000,000	46,000,000	45,000,000
Amortization Method Qualified Affordable Housing Project Investments, Amortization		17,000,000	14,000,000	45,000,000	(41,000,000)
Amortization of Intangible Assets	[3]			6,000,000	10,000,000
Amortization		9,000,000	7,000,000	22,000,000	14,000,000
Other Noninterest Expense		95,000,000	83,000,000	286,000,000	333,000,000
Affordable Housing Investment [Member]
Gains (Losses) on Sales of Investment Real Estate				19,000,000
Properties sold, carrying value				72,000,000
Variable Interest Entity, Not Primary Beneficiary [Member] | Community Development Investments [Member]
Amortization of Intangible Assets		8,000,000	4,000,000	18,000,000	9,000,000
Amortization			4,000,000		4,000,000
Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt		270,000,000		270,000,000			302,000,000
Residential Mortgage [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Loans and Leases Receivable, Gain (Loss) on Sales, Net		48,000,000	50,000,000	171,000,000	155,000,000
Transferor's Interests in Transferred Financial Assets, Fair Value		43,000,000		43,000,000			55,000,000
Assets		251,000,000		251,000,000			288,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Total liabilities		541,000,000		541,000,000			654,000,000
Assets		584,000,000		584,000,000			704,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Preference Shares [Member]
Assets		2,000,000		2,000,000			3,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Senior Subordinated Notes [Member]
Assets		11,000,000		11,000,000			18,000,000
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt		270,000,000		270,000,000			302,000,000
Loans Receivable, Net		$ 273,000,000		$ 273,000,000			$ 306,000,000
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Government Guarantee Percent		100.00%		100.00%
Total Return Swap | Variable Interest Entity, Not Primary Beneficiary [Member]
Trading assets		$ 2,400,000,000		$ 2,400,000,000			$ 2,300,000,000
Derivative, Notional Amount		2,400,000,000		2,400,000,000			2,300,000,000
Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Assets		1,900,000,000		1,900,000,000			1,600,000,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		255,000,000		255,000,000			236,000,000
Real Estate Variable Interest Entity Borrowings		130,000,000		130,000,000			113,000,000
Limited Partner [Member] | Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Other Assets		552,000,000		552,000,000			363,000,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount		1,079,000,000		1,079,000,000			910,000,000
Loans issued by the Company to the limited partnerships		396,000,000		396,000,000			$ 412,000,000
Affordable Housing [Member]
Gains (Losses) on Sales of Investment Real Estate		$ 0		(19,000,000)
Other Expense [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Community Development Investments [Member]
Amortization			$ 0		$ 5,000,000
Consumer Portfolio Segment [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member]
Principal Amount Outstanding on Loans Securitized or Asset-backed Financing Arrangement						$ 1,000,000,000
Proceeds from Securitizations of Consumer Loans				$ 1,000,000,000

[1] Includes debt of consolidated VIEs of $270 million and $302 million at September 30, 2015 and December 31, 2014, respectively.

[2] Includes trading securities pledged as collateral where counterparties have the right to sell or repledge the collateral of $1,152 million and $1,316 million at September 30, 2015 and December 31, 2014, respectively

[3] Does not include amortization of tax credits for non-qualified community development investments. See Note 8, "Certain Transfers of Financial Assets and Variable Interest Entities," for additional information.