Fair Value Measurement and Election - Additional Information (Detail) (USD $)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Estimated Fair Value of Loan Portfolio's Net Carrying Value, Percentage	100.00%			100.00%		99.00%
Assets	$ 186,818,000,000			$ 186,818,000,000		$ 175,335,000,000
Transfer of Loans Held-for-sale to Portfolio Loans	19,000,000		11,000,000	39,000,000	28,000,000
Loans Receivable, Fair Value Disclosure	284,000,000			284,000,000		302,000,000
Allowance for Loan and Lease Losses, Write-offs	164,000,000		189,000,000	473,000,000	695,000,000
Loans held for investment sold	2,300,000,000		99,000,000	3,000,000,000	761,000,000
Gain (Loss) on Sales of Loans, Net	40,000,000		1,000,000	71,000,000	7,000,000
Unfunded loan commitments and letters of credit	56,000,000,000			56,000,000,000		48,900,000,000
Allowance for unfunded loan commitments and letters of credit	46,000,000			46,000,000		53,000,000
Total Return Swap | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure	1,700,000,000			1,700,000,000		1,500,000,000
Interest Rate Lock Commitments [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(64,000,000)		(50,000,000)	(181,000,000)	159,000,000
Asset-backed Securities [Member] | Student Loans [Member]
Government guaranteed percent						97.00%
Trading Account Assets [Member] | Commercial and Corporate Leveraged Loans [Member] | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure	373,000,000			373,000,000		313,000,000
Fair Value, Option, Credit Risk, Gains (Losses) on Assets			1,000,000		2,000,000
Residential Mortgage, Loans Held For Sale [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Option, Credit Risk, Gains (Losses) on Assets			2,000,000
Residential Mortgage, Loans Held For Sale [Member] | Nonperforming Financing Receivable [Member]
Loans held for investment sold						(39,000,000)
Collateralized Loan Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Option, Credit Risk, Gains (Losses) on Assets	0		1,000,000	0	2,000,000
Long-term Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Option, Credit Risk, Gains (Losses) on Liabilities	(2,000,000)		9,000,000	24,000,000	27,000,000
Loans Held For Sale [Member] | Nonperforming Financing Receivable [Member]
Transfer Of Portfolio Loans And Leases To Held For Sale Net Of Impairment	53,000,000			53,000,000	22,000,000
Loans sold at carrying value				10,000,000
Loans Held For Sale [Member] | Residential Portfolio Segment [Member]
Gain (Loss) on Sales of Loans, Net					5,000,000
Loans Held For Sale [Member] | Nonperforming Residential Mortgages Transferred To Held For Sale During Period [Member]
Allowance for Loan and Lease Losses, Write-offs	9,000,000				3,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Assets	742,000,000			742,000,000		1,600,000,000
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Preference Shares [Member]
Assets	5,000,000			5,000,000		3,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure	0			0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Loans Receivable, Fair Value Disclosure	284,000,000			284,000,000		302,000,000
Other Real Estate Owned [Member] | Fair Value, Measurements, Nonrecurring [Member]
Asset Impairment Charges	5,000,000			9,000,000		10,000,000
Other Assets [Member] | Fair Value, Measurements, Nonrecurring [Member]
Asset Impairment Charges	49,000,000			62,000,000		61,000,000
Other Assets [Member] | Fair Value, Measurements, Nonrecurring [Member] | Land [Member]
Asset Impairment Charges	5,000,000		0	5,000,000	0
Other Assets [Member] | Fair Value, Measurements, Nonrecurring [Member] | Property Subject to Operating Lease [Member]
Asset Impairment Charges	49,000,000		38,000,000	57,000,000	39,000,000
Affordable Housing [Member] | Fair Value, Measurements, Nonrecurring [Member]
Asset Impairment Charges	$ (8,000,000)	$ 36,000,000	$ 9,000,000	$ 28,000,000	$ (9,000,000)	$ 3,000,000