LOAN PORTFOLIO - Corporation's Aging of Loans Held for Investment Portfolio (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012 Payment	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans considered to be defaulted if borrower has failed to make payment for a period or more than the period	90 days
Period during which credit card loans continue to accrue finance charges and fees	180 days
Defaulted loans collateralizing Ginnie Mae (GNMA) securities	$ 6.1	$ 66.4
Minimum Number of Payments in Arrears to Consider Commercial Mortgage and Construction Loan as Past Due	2
Residential mortgage loans insured by FHA or guaranteed by the VA	$ 34.6
Period of residential mortgage loan that are no longer accruing interest	18 months

Defaulted loans collateralizing Ginnie Mae (GNMA) securities.

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Insured Residential Mortgage Loans That Are Not Accruing Interest

No definition available.

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Loans considered to be defaulted if borrower has failed to make payment for period or more than period.

No definition available.

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Minimum number of payments in arrears to consider commercial mortgage and construction loan as past due.

No definition available.

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Period during which credit card loans continue to accrue finance charges and fees.

No definition available.

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Period of residential mortgage loan that are no longer accruing interest.

No definition available.

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