LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Loans by Type) (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	$ 3,235,714,000	$ 3,296,338,000
Less allowance for loan losses	(77,491,000)	(82,912,000)	(97,401,000)
Total loans	3,158,223,000	3,213,426,000
Percent of total loans	100.00%	100.00%
Unearned, unamortized loan fees (and costs)	9,000,000	10,000,000
Commerical real estate - owner-occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	489,581,000	469,806,000
Percent of total loans	15.10%	14.20%
Commerical real estate - investment properties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	583,641,000	621,622,000
Percent of total loans	18.00%	18.90%
Multifamily real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	137,504,000	139,710,000
Percent of total loans	4.30%	4.20%
Commercial construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	30,229,000	42,391,000
Percent of total loans	0.90%	1.30%
Multifamily construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	22,581,000	19,436,000
Percent of total loans	0.70%	0.60%
One-to four-family construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	160,815,000	144,177,000
Percent of total loans	5.00%	4.40%
Land and land development - residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	77,010,000	97,491,000
Percent of total loans	2.40%	3.00%
Land and land development - commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	13,982,000	15,197,000
Percent of total loans	0.40%	0.50%
Commercial business [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	618,049,000	601,440,000
Percent of total loans	19.10%	18.20%
Agricultural business, including secured by farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	230,031,000	218,171,000
Percent of total loans	7.10%	6.60%
One- to four-family real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	581,670,000	642,501,000
Percent of total loans	18.00%	19.50%
Consumer secured by one- to four-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	170,123,000	181,049,000
Percent of total loans	5.30%	5.50%
Consumer - other Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	$ 120,498,000	$ 103,347,000
Percent of total loans	3.70%	3.10%