Derivative Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Derivative [Line Items]
Collateral from counterparties to offset changes in the fair value of derivative assets	$ 1,200	$ 903
Valuation adjustments related to the credit risk associated with counterparties of customer accommodation derivative contracts	28	41
Collateral from counterparties to offset changes in the fair value of derivative liabilities	788	680
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	80	67
Net deferred gains, net of tax, recorded in accumulated other comprehensive income are expected to be reclassified into earnings	70
Interest Rate Contract \| Lender Concentration Risk
Derivative [Line Items]
Notional amount of the risk participation agreements	808	851
Credit Risk Derivatives Average Life	2.5
Interest Rate Contract \| Lender Concentration Risk \| Servicing Contracts
Derivative [Line Items]
Fair value of risk participation agreements	$ 2	$ 1

Credit Risk Derivatives, Average Life

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- Definition

Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

The amount as of the balance sheet date of the fair value of derivative assets that in accordance with the entity's accounting policy was not offset against an obligation to return cash collateral under a master netting arrangement.

+ References

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- Definition

The amount as of the balance sheet date of the fair value of derivative liabilities that in accordance with the entity's accounting policy were offset against the right to reclaim cash collateral under a master netting arrangement.

+ References

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- Definition

The net gain (loss) recognized in earnings in the period relating to components of the gain (loss) on credit risk hedging instruments excluded from the assessment of hedge effectiveness.

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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- Definition

The amount of net gain (loss) reclassified into earnings when interest rate cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

+ References

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- Definition

The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

+ References

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-Publisher FASB

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- Definition

Aggregate notional amount of all derivatives not designated as a hedging instrument. The notional amount relates to a number of currency units, shares, bushels, pounds, or other units specified in a derivative instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

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Fair value of all derivative liabilities not designated as a hedging instrument.

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

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