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Commitments and Letters of Credit - Notional Amount of Commitments and Letter of Credit Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Commitments to extend credit [Member]
Contingencies And Commitments [Line Items]
Financial instrument of credit risk	$ 1,506,618	$ 1,495,009
Financial standby letters of credit [Member]
Contingencies And Commitments [Line Items]
Financial instrument of credit risk	47,185	53,689
Performance standby letters of credit [Member]
Contingencies And Commitments [Line Items]
Financial instrument of credit risk	69,240	76,371
Commercial letters of credit [Member]
Contingencies And Commitments [Line Items]
Financial instrument of credit risk	$ 685	$ 1,297

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- Details

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- Definition

Notional amount of outstanding commitments and letters of credit.

+ References

No definition available.

+ Details

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