Certain Transfers of Financial Assets and Variable Interest Entities - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
Cash Flows Between Transferor and Transferee, Receipts on Transferor's Interest in Transferred Financial Assets, Other	$ 4,000,000		$ 4,000,000
Total assets	189,881,000,000			190,328,000,000
Loans Receivable Held-for-sale, Net	3,404,000,000	[1]		3,232,000,000	[1]
Long-term Debt	13,012,000,000	[2]		13,022,000,000	[2]
Total liabilities	166,621,000,000			167,323,000,000
LHFS excluded from managed loans disclosure	3,400,000,000			3,200,000,000
Trading assets	6,595,000,000	[3]		6,202,000,000	[3]
Derivative Asset, Fair Value, Gross Asset	6,067,000,000			5,839,000,000
Derivative Liability, Fair Value, Gross Liability	5,728,000,000			5,577,000,000
Other Assets	5,872,000,000			5,656,000,000
Investment Tax Credit	14,000,000		15,000,000
Amortization of Intangible Assets and Impairment of Goodwill	7,000,000		3,000,000
Affordable Housing Investment [Member]
Real Estate Held for Development and Sale	63,000,000
Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt	292,000,000			302,000,000
Residential Mortgage [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Loans and Leases Receivable, Gain (Loss) on Sales, Net	77,000,000		43,000,000
Transferor's Interests in Transferred Financial Assets, Fair Value	52,000,000			55,000,000
Total assets	278,000,000			288,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Total assets	677,000,000			704,000,000
Total liabilities	628,000,000			654,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Preference Shares [Member]
Total assets	3,000,000			3,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Senior Subordinated Notes [Member]
Total assets	16,000,000			18,000,000
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt	292,000,000			302,000,000
Loans Receivable, Net	295,000,000			306,000,000
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Government Guarantee Percent	97.00%
Total Return Swap | Variable Interest Entity, Not Primary Beneficiary [Member]
Trading assets	2,300,000,000			2,300,000,000
Derivative, Notional Amount	2,300,000,000			2,300,000,000
Derivative Asset, Fair Value, Gross Asset	20,000,000			19,000,000
Derivative Liability, Fair Value, Gross Liability	15,000,000			14,000,000
Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Total assets	1,700,000,000			1,600,000,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	222,000,000			236,000,000
Amortization of Intangible Assets and Impairment of Goodwill	6,000,000		3,000,000
Real Estate Variable Interest Entity Borrowings	114,000,000			113,000,000
Limited Partner [Member] | Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Other Assets	441,000,000			363,000,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	912,000,000			910,000,000
Loans issued by the Company to the limited partnerships	379,000,000			412,000,000
provision for income taxes [Member]
Other Depreciation and Amortization	$ 14,000,000		$ 13,000,000

[1] Includes $2.1 billion and $1.9 billion of LHFS carried at fair value at March 31, 2015 and December 31, 2014, respectively.

[2] Includes debt of consolidated VIEs of $292 million and $302 million at March 31, 2015 and December 31, 2014, respectively.

[3] Includes trading securities pledged as collateral where counterparties have the right to sell or repledge the collateral of $1,207 million and $1,316 million at March 31, 2015 and December 31, 2014, respectively