LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Loans by Type) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	$ 3,418,445,000	$ 3,235,714,000
Less allowance for loan losses	(74,990,000)	(77,491,000)	(82,912,000)
Total loans	3,343,455,000	3,158,223,000
Percent of total loans	100.00%	100.00%
Unearned, unamortized loan fees (and costs)	8,300,000	9,000,000
Commerical real estate - owner-occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	502,601,000	489,581,000
Percent of total loans	14.70%	15.10%
Commerical real estate - investment properties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	692,457,000	583,641,000
Percent of total loans	20.30%	18.00%
Multifamily real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	137,153,000	137,504,000
Percent of total loans	4.00%	4.30%
Commercial construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	12,168,000	30,229,000
Percent of total loans	0.40%	0.90%
Multifamily construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	52,081,000	22,581,000
Percent of total loans	1.50%	0.70%
One-to four-family construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	200,864,000	160,815,000
Percent of total loans	5.80%	5.00%
Land and land development - residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	75,695,000	77,010,000
Percent of total loans	2.20%	2.40%
Land and land development - commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	10,450,000	13,982,000
Percent of total loans	0.30%	0.40%
Commercial business [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	682,169,000	618,049,000
Less allowance for loan losses	(11,773,000)	(9,957,000)	(15,159,000)
Percent of total loans	20.00%	19.10%
Agricultural business, including secured by farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	228,291,000	230,031,000
Less allowance for loan losses	(2,841,000)	(2,295,000)	(1,548,000)
Percent of total loans	6.70%	7.10%
One- to four-family real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	529,494,000	581,670,000
Percent of total loans	15.50%	18.00%
Consumer secured by one- to four-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	173,188,000	170,123,000
Percent of total loans	5.10%	5.30%
Consumer - other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	$ 121,834,000	$ 120,498,000
Percent of total loans	3.50%	3.70%