Certain Transfers of Financial Assets and Variable Interest Entities - Additional Information (Detail) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Cash Flows Between Transferor and Transferee, Receipts on Transferor's Interest in Transferred Financial Assets, Other	$ 2,000,000		$ 8,000,000	$ 14,000,000		$ 26,000,000
Total assets	186,818,000,000			186,818,000,000			175,335,000,000
Loans Receivable Held-for-sale, Net	1,739,000,000	[1],[2]		1,739,000,000	[1],[2]		1,699,000,000	[1]
Long-term Debt	12,942,000,000	[3]		12,942,000,000	[3]		10,700,000,000	[3]
Total liabilities	164,549,000,000			164,549,000,000			153,913,000,000
LHFS excluded from managed loans disclosure	1,700,000,000			1,700,000,000			1,700,000,000
Trading assets	5,782,000,000			5,782,000,000			5,040,000,000
Derivative Asset, Fair Value, Gross Asset	5,340,000,000			5,340,000,000			6,125,000,000
Derivative Liability, Fair Value, Gross Liability	5,027,000,000			5,027,000,000			5,673,000,000
Other Assets	5,354,000,000			5,354,000,000			5,520,000,000
Investment Tax Credit	15,000,000		16,000,000	45,000,000		45,000,000
Noninterest Income	780,000,000		680,000,000	2,528,000,000		2,401,000,000
Affordable Housing Investment [Member]
Real Estate Held for Development and Sale	72,000,000			72,000,000
Variable Interest Entity, Primary Beneficiary [Member]
Loans Receivable Held-for-sale, Net	0			0			261,000,000
Long-term Debt	312,000,000			312,000,000			597,000,000
Residential Mortgage [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Loans and Leases Receivable, Gain (Loss) on Sales, Net	50,000,000		(169,000,000)	155,000,000		112,000,000
Transferor's Interests in Transferred Financial Assets, Fair Value	65,000,000			65,000,000			71,000,000
Total assets	297,000,000			297,000,000			350,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Total assets	742,000,000			742,000,000			1,600,000,000
Total liabilities	693,000,000			693,000,000			1,600,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Preference Shares [Member]
Total assets	5,000,000			5,000,000			3,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Senior Subordinated Notes [Member]
Total assets	19,000,000			19,000,000			26,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt							256,000,000
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt	312,000,000			312,000,000			341,000,000
Loans Receivable, Net	315,000,000			315,000,000			344,000,000
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Government guaranteed percent	97.00%			97.00%			97.00%
Total Return Swap | Variable Interest Entity, Not Primary Beneficiary [Member]
Trading assets	1,700,000,000			1,700,000,000			1,500,000,000
Derivative, Notional Amount	1,700,000,000			1,700,000,000			1,500,000,000
Derivative Asset, Fair Value, Gross Asset	10,000,000			10,000,000			35,000,000
Derivative Liability, Fair Value, Gross Liability	7,000,000			7,000,000			31,000,000
Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Total assets	1,500,000,000			1,500,000,000			1,500,000,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	242,000,000			242,000,000			217,000,000
Real Estate Variable Interest Entity Borrowings	146,000,000			146,000,000			138,000,000
Limited Partner [Member] | Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Other Assets	300,000,000			300,000,000			252,000,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	806,000,000			806,000,000			697,000,000
Loans issued by the Company to the limited partnerships	361,000,000			361,000,000			303,000,000
Partnership [Member] | Community Development Investments [Member]
Total assets	115,000,000			115,000,000			151,000,000
Total liabilities	55,000,000			55,000,000			58,000,000
provision for income taxes [Member]
Other Depreciation and Amortization	14,000,000		13,000,000	41,000,000		33,000,000
Residential Mortgage [Member]
Cash Flows Between Transferor and Transferee, Receipts on Transferor's Interest in Transferred Financial Assets, Other	$ 2,000,000		$ 8,000,000	$ 13,000,000	[4],[5]	$ 24,000,000

[1] Includes $1.6 billion and $1.4 billion of LHFS carried at fair value at September 30, 2014 and December 31, 2013, respectively.

[2] Includes loans held for sale, at fair value, of consolidated VIEs of $0 million and $261 million at September 30, 2014 and December 31, 2013, respectively.

[3] Includes debt of consolidated VIEs of $312 million and $597 million at September 30, 2014 and December 31, 2013, respectively, of which $0 million and $256 million are carried at fair value at September 30, 2014 and December 31, 2013, respectively.

[4] The transfer activity is related to unconsolidated VIEs.

[5] Does not include GSE mortgage loan transfers