FAIR VALUE DISCLOSURES (Estimated Fair Value of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Investment securities:
Available for sale	$ 1,554,442us-gaap_AvailableForSaleSecurities	$ 1,445,689us-gaap_AvailableForSaleSecurities
Held-to-maturity Securities, Fair Value	597,341	614,272
Estimate of Fair Value, Fair Value Disclosure [Member]
Financial Assets:
Cash and cash equivalents	230,735	205,402
Investment securities:
Available for sale	1,554,442	1,445,689
Held-to-maturity Securities, Fair Value	597,341	614,272
Loans held for portfolio	3,096,743	2,937,948
Loans held for sale	43,655	31,411
Derivative instruments	984	286
Accrued interest receivable	15,867	15,064
Financial Liabilities:
Deposits	4,971,623	4,848,582
Securities sold under agreements to repurchase	51,032	64,875
Accrued interest payable	830	831
Subordinated debentures	270,473	303,191
Liability for Off-Balance Sheet Financial Instruments:
Commitments to extend credit, standby letters of credit and financial guarantees	12	12
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Cash and cash equivalents	230,735	205,402
Investment securities:
Available for sale	1,985	1,967
Held-to-maturity Securities, Fair Value	0	0
Loans held for portfolio	0	0
Loans held for sale	0	0
Derivative instruments	0	0
Accrued interest receivable	15,867	15,064
Financial Liabilities:
Deposits	4,049,806	3,923,627
Securities sold under agreements to repurchase	51,032	64,875
Accrued interest payable	830	831
Subordinated debentures	0	0
Liability for Off-Balance Sheet Financial Instruments:
Commitments to extend credit, standby letters of credit and financial guarantees	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Cash and cash equivalents	0	0
Investment securities:
Available for sale	1,552,457	1,443,722
Held-to-maturity Securities, Fair Value	597,341	614,272
Loans held for portfolio	0	0
Loans held for sale	43,655	31,411
Derivative instruments	984	286
Accrued interest receivable	0	0
Financial Liabilities:
Deposits	0	0
Securities sold under agreements to repurchase	0	0
Accrued interest payable	0	0
Subordinated debentures	0	0
Liability for Off-Balance Sheet Financial Instruments:
Commitments to extend credit, standby letters of credit and financial guarantees	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Cash and cash equivalents	0	0
Investment securities:
Available for sale	0	0
Held-to-maturity Securities, Fair Value	0	0
Loans held for portfolio	3,096,743	2,937,948
Loans held for sale	0	0
Derivative instruments	0	0
Accrued interest receivable	0	0
Financial Liabilities:
Deposits	921,817	924,955
Securities sold under agreements to repurchase	0	0
Accrued interest payable	0	0
Subordinated debentures	270,473	303,191
Liability for Off-Balance Sheet Financial Instruments:
Commitments to extend credit, standby letters of credit and financial guarantees	12	12
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Financial Assets:
Cash and cash equivalents	230,735	205,402
Investment securities:
Available for sale	1,554,442	1,445,689
Held-to-maturity Securities, Fair Value	595,335	618,148
Loans held for portfolio	3,085,600	3,050,958
Loans held for sale	43,655	31,411
Derivative instruments	984	286
Accrued interest receivable	15,867	15,064
Financial Liabilities:
Deposits	4,972,089	4,849,504
Securities sold under agreements to repurchase	51,032	64,875
Accrued interest payable	830	831
Subordinated debentures	354,305	354,286
Liability for Off-Balance Sheet Financial Instruments:
Commitments to extend credit, standby letters of credit and financial guarantees	$ 12	$ 12

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Fair value portion of amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties.

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Fair value portion of accrued expenses.

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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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The fair value of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

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Fair value of investments in debt securities classified as held-to-maturity.

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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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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 other liabilities.

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