LOAN PORTFOLIO - Loan Portfolio Held for Investment (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Financial Information [Line Items]
Residential mortgage loans, mainly secured by first mortgages	$ 2,762,418	$ 2,873,785
Commercial loans:
Construction loans	352,891	427,863
Commercial mortgage loans	1,459,118	1,565,411
Commercial and Industrial loans	3,369,305	3,856,695
Loans to local financial institutions collateralized by real estate mortgages	258,341	273,821
Commercial loans	5,439,655	6,123,790
Finance leases	239,556	247,003
Consumer loans	1,746,535	1,314,814
Loans held for investment	10,188,164	10,559,392
Allowance for loan and lease losses	(445,531)	(493,917)	(1,394)
Loans held for investment, net	$ 9,742,633	$ 10,065,475	$ 10,633,142

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Loans to local financial institution collateralized by real estate mortgages.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance of commercial loans and leases receivable includes, but not limited to, commercial and industrial loans, agricultural loans, mortgage loans, promissory notes, interbank and other loans to financial institutions, draws against credit facilities, trade financing, lease financings. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of consumer loans, including, but not limited to, mortgage, home equity, vehicles, credit card, installment, and lease financing. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of consumer real estate loans. Includes, but not limited to, construction financing, residential mortgage loans, and home equity lines of credit. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Reflects the aggregate gross carrying amount of all loans and leases held in portfolio, not otherwise categorized (such as commercial, consumer, or foreign), prior to deducting deferred income and the allowance for losses on loans and leases, not otherwise categorized (such as commercial, consumer, or foreign).

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of loans issued to commercial and industrial institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes real estate loans and loans covered under loss sharing agreements.

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Amount before allowance of commercial construction loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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Amount before allowance of mortgage loans on existing land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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