LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Age Analysis of Company's Past Due Loans) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	$ 4,511	$ 9,870
60 to 89 Days Past Due	4,058	4,264
Greater Than 90 Days Past Due	12,752	19,267
Total Past Due	21,321	33,401
Current	3,268,880	3,202,313
Total loans outstanding	3,290,201	3,235,714	3,212,257
Loans 90 Days or More Past Due and Accruing	1,959	3,029
Commerical real estate - owner-occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	59	1,693
60 to 89 Days Past Due	400	0
Greater Than 90 Days Past Due	1,391	1,371
Total Past Due	1,850	3,064
Current	498,962	486,517
Total loans outstanding	500,812	489,581	477,621
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	2,249	743
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	1,405	1,431
Total Past Due	3,654	2,174
Current	592,242	581,467
Total loans outstanding	595,896	583,641	613,965
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	137,027	137,504
Total loans outstanding	137,027	137,504	130,319
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	0
Total Past Due	0	0
Current	25,629	30,229
Total loans outstanding	25,629	30,229	23,808
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	39,787	22,581
Total loans outstanding	39,787	22,581	18,132
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	208	611
60 to 89 Days Past Due	0	0
Greater Than 90 Days Past Due	538	0
Total Past Due	746	611
Current	190,257	160,204
Total loans outstanding	191,003	160,815	157,301
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	1,011	2,047
Total Past Due	1,011	2,047
Current	85,026	74,963
Total loans outstanding	86,037	77,010	83,185
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	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	11,228	11,854
Total loans outstanding	11,228	13,982	11,451
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	706	1,849
60 to 89 Days Past Due	263	49
Greater Than 90 Days Past Due	551	842
Total Past Due	1,520	2,740
Current	638,320	615,309
Total loans outstanding	639,840	618,049	600,046
Loans 90 Days or More Past Due and Accruing	4	0
Agricultural business, including secured by farming [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	233	0
60 to 89 Days Past Due	125	0
Greater Than 90 Days Past Due	0	0
Total Past Due	358	0
Current	233,609	230,031
Total loans outstanding	233,967	230,031	211,705
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	404	1,376
60 to 89 Days Past Due	2,432	3,468
Greater Than 90 Days Past Due	6,609	11,488
Total Past Due	9,445	16,332
Current	543,253	565,338
Total loans outstanding	552,698	581,670	607,489
Loans 90 Days or More Past Due and Accruing	1,897	2,877
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	427	816
60 to 89 Days Past Due	240	673
Greater Than 90 Days Past Due	650	839
Total Past Due	1,317	2,328
Current	111,621	118,170
Total loans outstanding	112,938	120,498	103,504
Loans 90 Days or More Past Due and Accruing	58	152
Consumer secured by one- to four-family [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	225	699
60 to 89 Days Past Due	598	74
Greater Than 90 Days Past Due	597	1,204
Total Past Due	1,420	1,977
Current	161,919	168,146
Total loans outstanding	163,339	170,123	173,731
Loans 90 Days or More Past Due and Accruing	$ 0	$ 0