LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Age Analysis of Company's Past Due Loans) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	$ 9,870	$ 7,886
60 to 89 Days Past Due	4,264	7,930
Greater Than 90 Days Past Due	19,267	53,401
Total Past Due	33,401	69,217
Current	3,202,313	3,227,121
Total loans outstanding	3,235,714	3,296,338
Loans 90 Days or More Past Due and Accruing	3,029	2,324
Commerical real estate - owner-occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	1,693	1,251
60 to 89 Days Past Due	0	2,703
Greater Than 90 Days Past Due	1,371	3,462
Total Past Due	3,064	7,416
Current	486,517	462,390
Total loans outstanding	489,581	469,806
Loans 90 Days or More Past Due and Accruing	0	0
Commerical real estate - investment properties [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	743	0
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	1,431	3,087
Total Past Due	2,174	3,087
Current	581,467	618,535
Total loans outstanding	583,641	621,622
Loans 90 Days or More Past Due and Accruing	0	0
Multifamily real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0	0
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	0	0
Total Past Due	0	0
Current	137,504	139,710
Total loans outstanding	137,504	139,710
Loans 90 Days or More Past Due and Accruing	0	0
Commercial construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0	0
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	0	949
Total Past Due	0	949
Current	30,229	41,442
Total loans outstanding	30,229	42,391
Loans 90 Days or More Past Due and Accruing	0	0
Multifamily construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0	0
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	0	0
Total Past Due	0	0
Current	22,581	19,436
Total loans outstanding	22,581	19,436
Loans 90 Days or More Past Due and Accruing	0	0
One-to four-family construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	611	643
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	0	3,819
Total Past Due	611	4,462
Current	160,204	139,715
Total loans outstanding	160,815	144,177
Loans 90 Days or More Past Due and Accruing	0	0
Land and land development - residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0	638
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	2,047	15,919
Total Past Due	2,047	16,557
Current	74,963	80,934
Total loans outstanding	77,010	97,491
Loans 90 Days or More Past Due and Accruing	0	0
Land and land development - commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	2,083	308
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	45	791
Total Past Due	2,128	1,099
Current	11,854	14,098
Total loans outstanding	13,982	15,197
Loans 90 Days or More Past Due and Accruing	0	0
Commercial business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	1,849	2,411
60 to 89 Days Past Due	49	4,170
Greater Than 90 Days Past Due	842	5,612
Total Past Due	2,740	12,193
Current	615,309	589,247
Total loans outstanding	618,049	601,440
Loans 90 Days or More Past Due and Accruing	0	4
Agricultural business, including secured by farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0	99
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	0	1,849
Total Past Due	0	1,948
Current	230,031	216,223
Total loans outstanding	230,031	218,171
Loans 90 Days or More Past Due and Accruing	0	0
One- to four-family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	1,376	794
60 to 89 Days Past Due	3,468	585
Greater Than 90 Days Past Due	11,488	15,770
Total Past Due	16,332	17,149
Current	565,338	625,352
Total loans outstanding	581,670	642,501
Loans 90 Days or More Past Due and Accruing	2,877	2,147
Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	699	1,072
60 to 89 Days Past Due	74	109
Greater Than 90 Days Past Due	1,204	1,374
Total Past Due	1,977	2,555
Current	168,146	178,494
Total loans outstanding	170,123	181,049
Loans 90 Days or More Past Due and Accruing	0	148
Consumer - other Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	816	670
60 to 89 Days Past Due	673	363
Greater Than 90 Days Past Due	839	769
Total Past Due	2,328	1,802
Current	118,170	101,545
Total loans outstanding	120,498	103,347
Loans 90 Days or More Past Due and Accruing	$ 152	$ 25