Certain Transfers of Financial Assets and Variable Interest Entities - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows Between Transferor and Transferee, Receipts on Transferor's Interest in Transferred Financial Assets, Other			$ 19	$ 21	$ 36
Long-term Debt	[1]		8,462	13,022
Total liabilities			167,380	167,323
Total assets			$ 190,817	190,328
Government Guarantee Percent			2.00%
Trading assets	[2]		$ 6,119	6,202
Derivative Asset, Fair Value, Gross Asset			4,465	5,839
Derivative Liability, Fair Value, Gross Liability			4,428	5,577
Other Assets			5,582	5,656
Affordable Housing Tax Credits and Other Tax Benefits, Amount			68	66	64
Amortization Method Qualified Affordable Housing Project Investments, Amortization			66	61	49
Amortization of Intangible Assets	[3]		8	12
Amortization			40	25	23
Other Noninterest Expense	[4]		441	498	549
Affordable Housing Investment [Member]
Gains (Losses) on Sales of Investment Real Estate			19		17
Properties sold, carrying value			72
Variable Interest Entity, Not Primary Beneficiary [Member] | Community Development Investments [Member]
Amortization of Intangible Assets			35	19
Amortization				14
Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt			259	302
Residential Mortgage [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Loans and Leases Receivable, Gain (Loss) on Sales, Net			232	224	$ 186
Transferor's Interests in Transferred Financial Assets, Fair Value			38	55
Total assets			241	288
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Total liabilities			482	654
Total assets			525	704
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Preference Shares [Member]
Total assets			2	3
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Senior Subordinated Notes [Member]
Total assets			8	18
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt			259	302
Loans Receivable, Net			$ 262	306
Student Loans [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Government Guarantee Percent			100.00%
Total Return Swap [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Trading assets			$ 2,200	2,300
Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Total assets			1,600	1,400
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount			321	236
Real Estate Variable Interest Entity Borrowings			132	113
Limited Partner [Member] | Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Other Assets			672	363
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount			1,064	776
Loans issued by the Company to the limited partnerships			268	278
Affordable Housing [Member]
Gains (Losses) on Sales of Investment Real Estate			$ (19)
Other Expense [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Community Development Investments [Member]
Amortization				$ 5
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
Proceeds from Securitizations of Consumer Loans		$ 1,000

[1] Includes debt of consolidated VIEs of $259 million and $302 million at December 31, 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 $1,377 million and $1,316 million at December 31, 2015 and December 31, 2014, respectively

[3] 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.

[4] Amortization expense related to qualified affordable housing investment costs is recognized in provision for income taxes for each of the periods presented as allowed by an accounting standard adopted in 2014. Accordingly, $49 million of related amortization expense for the year ended December 31, 2013 was reclassified from other noninterest expense to provision for income taxes.