LOANS (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Mar. 31, 2012	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Subtotal	$ 2,214,862	$ 2,234,037
Less: Allowance for loan losses	(51,817)	(53,400)	(52,757)	(51,260)	(48,495)	(45,007)
Net deferred loan fees	(462)	(328)
Loans, net	2,162,583	2,180,309
Ratio of loan to all loans (in hundredths)	100.00%	100.00%
Commercial and Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	789,071	751,156
Less: Allowance for loan losses	(19,696)	(22,830)	(22,134)	(22,999)	(22,549)	(21,479)
Ratio of loan to all loans (in hundredths)	35.60%	33.60%
Commercial Real Estate and Multi-family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	810,129	852,520
Ratio of loan to all loans (in hundredths)	36.60%	38.20%
Agri-business and Agricultural Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	220,945	237,929
Less: Allowance for loan losses	(1,419)	(695)	(538)	(948)	(1,194)	(1,318)
Ratio of loan to all loans (in hundredths)	10.00%	10.70%
Consumer 1-4 Family mortgage loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer loans	285,310	288,155
Ratio of loan to all loans (in hundredths)	12.90%	12.90%
Working Capital Lines of Credit Loans [Member] | Commercial and Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	413,394	373,768
Ratio of loan to all loans (in hundredths)	18.70%	16.70%
Non-working Capital Loans [Member] | Commercial and Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	375,677	377,388
Ratio of loan to all loans (in hundredths)	17.00%	16.90%
Construction and Land Development Loans [Member] | Commercial Real Estate and Multi-family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	84,416	82,284
Ratio of loan to all loans (in hundredths)	3.80%	3.70%
Owner Occupied Loans [Member] | Commercial Real Estate and Multi-family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	356,889	346,669
Ratio of loan to all loans (in hundredths)	16.10%	15.50%
Nonowner Occupied Loans [Member] | Commercial Real Estate and Multi-family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	333,237	385,090
Ratio of loan to all loans (in hundredths)	15.00%	1720.00%
Multifamily Loans [Member] | Commercial Real Estate and Multi-family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	35,587	38,477
Ratio of loan to all loans (in hundredths)	1.60%	1.70%
Loans Secured by Farmland [Member] | Agri-business and Agricultural Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	112,431	118,224
Ratio of loan to all loans (in hundredths)	5.10%	5.30%
Loans for Agricultural Production [Member] | Agri-business and Agricultural Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	108,514	119,705
Ratio of loan to all loans (in hundredths)	4.90%	5.40%
Other Commerical Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	63,681	58,278
Ratio of loan to all loans (in hundredths)	2.90%	2.60%
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans	1,883,826	1,899,883
Ratio of loan to all loans (in hundredths)	85.10%	85.00%
Closed End First Mortgage Loans [Member] | Consumer 1-4 Family mortgage loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer loans	105,057	106,999
Ratio of loan to all loans (in hundredths)	4.70%	4.80%
Open End and Junior Lien Loans [Member] | Consumer 1-4 Family mortgage loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer loans	171,063	175,694
Ratio of loan to all loans (in hundredths)	7.70%	7.90%
Residential Construction and Land Development Loans [Member] | Consumer 1-4 Family mortgage loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer loans	9,190	5,462
Ratio of loan to all loans (in hundredths)	0.40%	0.20%
Other Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer loans	45,726	45,999
Ratio of loan to all loans (in hundredths)	2.10%	2.10%
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total consumer loans	$ 331,036	$ 334,154
Ratio of loan to all loans (in hundredths)	14.90%	15.00%