Derivative Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Derivative [Line Items]
Collateral from counterparties to offset changes in the fair value of derivative assets	$ 927	$ 1,200
Valuation adjustments related to the credit risk associated with counterparties of customer accommodation derivative contracts	18	28
Collateral from counterparties to offset changes in the fair value of derivative liabilities	785	788
Cash Flow Hedging
Derivative [Line Items]
Maximum Length Of Time Hedged In Interest Rate Cash Flow Hedge	3 years 2 months
Reclassified gains (losses) from accumulated other comprehensive income into earnings as the original forecasted transaction was no longer probable of occurring within the originally specified time period		11
Interest Rate Floor | Cash Flow Hedging
Derivative [Line Items]
Deferred gains, net of tax, on cash flow hedges were recorded in accumulated other comprehensive income	50	80
Net deferred gains, net of tax, recorded in accumulated other comprehensive income are expected to be reclassified into earnings	20
Interest Rate Contract
Derivative [Line Items]
Average life of risk participation agreements	3 years
Interest Rate Contract | Lender Concentration Risk
Derivative [Line Items]
Notional amount of the risk participation agreements	1,006	808
Interest Rate Contract | Lender Concentration Risk | Servicing Contracts
Derivative [Line Items]
Free-standing derivative liability initial fair value with reversal of net Visa litigation reserve	$ 2	$ 2