LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Age Analysis of Company's Past Due Loans) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	$ 4,707	$ 9,870
60 to 89 Days Past Due	7,776	4,264
Greater Than 90 Days Past Due	15,321	19,267
Total Past Due	27,804	33,401
Current	3,247,632	3,202,313
Total loans outstanding	3,275,436	3,235,714	3,213,523
Loans 90 Days or More Past Due and Accruing	4,793	3,029
Commerical real estate - owner-occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	2,374	1,693
60 to 89 Days Past Due	1,675	0
Greater Than 90 Days Past Due	1,386	1,371
Total Past Due	5,435	3,064
Current	502,906	486,517
Total loans outstanding	508,341	489,581	477,871
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	92	743
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	1,499	1,431
Total Past Due	1,591	2,174
Current	612,166	581,467
Total loans outstanding	613,757	583,641	604,265
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	1,701	0
Total Past Due	1,701	0
Current	132,069	137,504
Total loans outstanding	133,770	137,504	138,716
Loans 90 Days or More Past Due and Accruing	1,701	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	0
Total Past Due	0	0
Current	18,730	30,229
Total loans outstanding	18,730	30,229	28,598
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	33,888	22,581
Total loans outstanding	33,888	22,581	14,502
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	0	611
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	910	0
Total Past Due	910	611
Current	193,277	160,204
Total loans outstanding	194,187	160,815	163,521
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	0
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	993	2,047
Total Past Due	993	2,047
Current	74,583	74,963
Total loans outstanding	75,576	77,010	79,932
Loans 90 Days or More Past Due and Accruing	242	0
Land and land development - commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0	2,083
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	0	45
Total Past Due	0	2,128
Current	11,231	11,854
Total loans outstanding	11,231	13,982	14,242
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	421	1,849
60 to 89 Days Past Due	57	49
Greater Than 90 Days Past Due	516	842
Total Past Due	994	2,740
Current	634,664	615,309
Total loans outstanding	635,658	618,049	603,606
Loans 90 Days or More Past Due and Accruing	24	0
Agricultural business, including secured by farming [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0	0
60 to 89 Days Past Due	108	0
Greater Than 90 Days Past Due	0	0
Total Past Due	108	0
Current	223,079	230,031
Total loans outstanding	223,187	230,031	219,084
Loans 90 Days or More Past Due and Accruing	0	0
One- to four-family real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	1,042	1,376
60 to 89 Days Past Due	5,129	3,468
Greater Than 90 Days Past Due	7,558	11,488
Total Past Due	13,729	16,332
Current	529,534	565,338
Total loans outstanding	543,263	581,670	594,413
Loans 90 Days or More Past Due and Accruing	2,774	2,877
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	319	816
60 to 89 Days Past Due	58	673
Greater Than 90 Days Past Due	475	839
Total Past Due	852	2,328
Current	112,977	118,170
Total loans outstanding	113,829	120,498	103,393
Loans 90 Days or More Past Due and Accruing	29	152
Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	459	699
60 to 89 Days Past Due	749	74
Greater Than 90 Days Past Due	283	1,204
Total Past Due	1,491	1,977
Current	168,528	168,146
Total loans outstanding	170,019	170,123	171,380
Loans 90 Days or More Past Due and Accruing	$ 23	$ 0