FAIR VALUE DISCLOSURES (Estimated Fair Value of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investment securities:
Available for sale	$ 1,445,689us-gaap_AvailableForSaleSecurities	$ 1,611,745us-gaap_AvailableForSaleSecurities
Held to maturity	614,272	719,183
FRB and FHLB stock	30,458	27,357	27,329
Carrying Value
Financial Assets:
Cash and cash equivalents	205,402	190,435
Investment securities:
Available for sale	1,445,689	1,611,745
Held to maturity	618,148	740,186
Loans held for portfolio	3,050,958	2,750,514
Loans held for sale	31,411	25,548
FRB and FHLB stock	30,458	27,357
Derivative assets	286	513
Accrued interest receivable	15,064	17,798
Financial Liabilities:
Deposits	4,849,504	4,813,895
Securities sold under agreements to repurchase	64,875	43,143
Accrued interest payable	831	63,341
Subordinated debentures	354,286	354,210
Liability for Off-Balance Sheet Financial Instruments:
Commitments to extend credit, standby letters of credit and financial guarantees	12	2,715
Estimated Fair Value [Member]
Financial Assets:
Cash and cash equivalents	205,402	190,435
Investment securities:
Available for sale	1,445,689	1,611,745
Held to maturity	614,272	719,183
Loans held for portfolio	2,937,948	2,562,160
Loans held for sale	31,411	25,548
FRB and FHLB stock	30,458	27,357
Derivative assets	286	513
Accrued interest receivable	15,064	17,798
Financial Liabilities:
Deposits	4,848,582	4,814,267
Securities sold under agreements to repurchase	64,875	43,143
Accrued interest payable	831	63,341
Subordinated debentures	303,191	242,678
Liability for Off-Balance Sheet Financial Instruments:
Commitments to extend credit, standby letters of credit and financial guarantees	12	2,715
Estimated Fair Value [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Cash and cash equivalents	205,402	190,435
Investment securities:
Available for sale	1,967	1,443
Held to maturity	0	0
Loans held for portfolio	0	0
Loans held for sale	0	0
FRB and FHLB stock	30,458	27,357
Derivative assets	0	0
Accrued interest receivable	15,064	17,798
Financial Liabilities:
Deposits	3,923,627	3,767,782
Securities sold under agreements to repurchase	64,875	43,143
Accrued interest payable	831	63,341
Subordinated debentures	0	0
Liability for Off-Balance Sheet Financial Instruments:
Commitments to extend credit, standby letters of credit and financial guarantees	0	0
Estimated Fair Value [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Cash and cash equivalents	0	0
Investment securities:
Available for sale	1,443,722	1,610,302
Held to maturity	614,272	719,183
Loans held for portfolio	0	0
Loans held for sale	31,411	25,548
FRB and FHLB stock	0	0
Derivative assets	286	513
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
Estimated Fair Value [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	0	0
Loans held for portfolio	2,937,948	2,562,160
Loans held for sale	0	0
FRB and FHLB stock	0	0
Derivative assets	0	0
Accrued interest receivable	0	0
Financial Liabilities:
Deposits	924,955	1,046,485
Securities sold under agreements to repurchase	0	0
Accrued interest payable	0	0
Subordinated debentures	303,191	242,678
Liability for Off-Balance Sheet Financial Instruments:
Commitments to extend credit, standby letters of credit and financial guarantees	$ 12	$ 2,715

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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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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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Amount of Federal Home Loan Bank (FHLB) and Federal Reserve Bank stock.

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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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