FAIR VALUE - Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets:
Investment securities available for sale	$ 1,965,666us-gaap_AvailableForSaleSecurities	$ 1,978,282us-gaap_AvailableForSaleSecurities
Less: allowance for loan and lease losses	(222,395)	(285,858)
Derivatives, included in assets	39us-gaap_DerivativeAssets	394us-gaap_DerivativeAssets
Liabilities:
Other borrowings	231,959	231,959
Derivatives, included in liabilities	187us-gaap_DerivativeLiabilities	4,023us-gaap_DerivativeLiabilities
Carrying Reported Amount Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	796,108	655,671
Investment securities available for sale	1,965,666	1,978,282
Other equity securities	25,752	28,691
Loans held for sale	76,956	75,969
Loans, held for investment	9,262,436	9,636,170
Less: allowance for loan and lease losses	(222,395)	(285,858)
Loans held for investment, net of allowance	9,040,041	9,350,312
Derivatives, included in assets	39	394
Liabilities:
Deposits	9,483,945	9,879,924
Securities sold under agreements to repurchase	900,000	900,000
Advances from FHLB	325,000	300,000
Notes Payable		0
Other borrowings	231,959	231,959
Derivatives, included in liabilities	187	4,023
Estimate Of Fair Value Fair Value Disclosure [Member]
Assets:
Cash and due from banks and money market investments	796,108	655,671
Investment securities available for sale	1,965,666	1,978,282
Other equity securities	25,752	28,691
Loans held for sale	77,888	76,684
Loans held for investment, net of allowance	8,844,659	9,127,234
Derivatives, included in assets	39	394
Liabilities:
Deposits	9,486,325	9,898,615
Securities sold under agreements to repurchase	958,715	976,151
Advances from FHLB	324,376	297,523
Notes Payable		0
Other borrowings	162,344	106,772
Derivatives, included in liabilities	187	4,023
Estimate Of Fair Value Fair Value Disclosure [Member] \| Fair Value Inputs Level 1 [Member]
Assets:
Cash and due from banks and money market investments	796,108	655,671
Investment securities available for sale	7,499	7,532
Other equity securities	0	0
Loans held for sale	0	0
Loans held for investment, net of allowance	0	0
Derivatives, included in assets	0	0
Liabilities:
Deposits	0	0
Securities sold under agreements to repurchase	0	0
Advances from FHLB	0	0
Other borrowings	0	0
Derivatives, included in liabilities	0	0
Estimate Of Fair Value Fair Value Disclosure [Member] \| Fair Value Inputs Level 2 [Member]
Assets:
Cash and due from banks and money market investments	0	0
Investment securities available for sale	1,921,955	1,927,458
Other equity securities	25,752	28,691
Loans held for sale	23,247	21,883
Loans held for investment, net of allowance	0	0
Derivatives, included in assets	39	394
Liabilities:
Deposits	9,486,325	9,898,615
Securities sold under agreements to repurchase	958,715	976,151
Advances from FHLB	324,376	297,523
Other borrowings	0	0
Derivatives, included in liabilities	187	4,023
Estimate Of Fair Value Fair Value Disclosure [Member] \| Fair Value Inputs Level 3 [Member]
Assets:
Cash and due from banks and money market investments	0	0
Investment securities available for sale	36,212	43,292
Other equity securities	0	0
Loans held for sale	54,641	54,801
Loans held for investment, net of allowance	8,844,659	9,127,234
Derivatives, included in assets	0	0
Liabilities:
Deposits	0	0
Securities sold under agreements to repurchase	0	0
Advances from FHLB	0	0
Other borrowings	162,344	106,772
Derivatives, included in liabilities	$ 0	$ 0

Loan and lease receivable gross fair value disclosure.

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The fair value amount of Equity securities, including FHLB stock and other equity securities.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

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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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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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No definition available.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Fair value portion of notes payable.

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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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