LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Allowance for Credit Losses) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 77,491	$ 82,912
Provision for loan losses	0	5,000
Recoveries	2,328	1,361
Charge-offs	(2,691)	(7,729)
Ending balance	77,128	81,544
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance individually evaluated for impairment	7,531	4,550
Allowance collectively evaluated for impairment	69,597	76,994
Total allowance for loan losses	77,128	81,544
Loans individually evaluated for impairment	72,632	72,390
Loans collectively evaluated for impairment	3,167,689	3,157,272
Total loans outstanding	3,240,321	3,229,662	3,235,714
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	15,322	16,457
Provision for loan losses	(1,784)	1,335
Recoveries	1,586	614
Charge-offs	(348)	(1,323)
Ending balance	14,776	17,083
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance individually evaluated for impairment	1,030	239
Allowance collectively evaluated for impairment	13,746	16,844
Total allowance for loan losses	14,776	17,083
Loans individually evaluated for impairment	12,632	13,123
Loans collectively evaluated for impairment	1,087,571	1,067,812
Total loans outstanding	1,100,203	1,080,935
Multifamily [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	4,506	3,952
Provision for loan losses	569	(691)
Recoveries	0	0
Charge-offs	0	0
Ending balance	5,075	3,261
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance individually evaluated for impairment	1,775	37
Allowance collectively evaluated for impairment	3,300	3,224
Total allowance for loan losses	5,075	3,261
Loans individually evaluated for impairment	7,075	1,635
Loans collectively evaluated for impairment	127,215	130,671
Total loans outstanding	134,290	132,306
Construction and Land [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	14,991	18,184
Provision for loan losses	557	241
Recoveries	101	370
Charge-offs	(435)	(2,924)
Ending balance	15,214	15,871
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance individually evaluated for impairment	2,008	2,100
Allowance collectively evaluated for impairment	13,206	13,771
Total allowance for loan losses	15,214	15,871
Loans individually evaluated for impairment	13,139	22,149
Loans collectively evaluated for impairment	318,569	288,871
Total loans outstanding	331,708	311,020
Commercial business [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	9,957	15,159
Provision for loan losses	597	(865)
Recoveries	386	236
Charge-offs	(929)	(1,407)
Ending balance	10,011	13,123
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance individually evaluated for impairment	285	799
Allowance collectively evaluated for impairment	9,726	12,324
Total allowance for loan losses	10,011	13,123
Loans individually evaluated for impairment	4,137	9,816
Loans collectively evaluated for impairment	615,341	599,681
Total loans outstanding	619,478	609,497
Agricultural business, including secured by farming [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	2,295	1,548
Provision for loan losses	(50)	614
Recoveries	37	0
Charge-offs	0	(275)
Ending balance	2,282	1,887
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance individually evaluated for impairment	0	480
Allowance collectively evaluated for impairment	2,282	1,407
Total allowance for loan losses	2,282	1,887
Loans individually evaluated for impairment	0	961
Loans collectively evaluated for impairment	210,225	187,994
Total loans outstanding	210,225	188,955
One To Four Family [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	16,475	12,299
Provision for loan losses	(10)	1,531
Recoveries	116	5
Charge-offs	(651)	(966)
Ending balance	15,930	12,869
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance individually evaluated for impairment	2,225	824
Allowance collectively evaluated for impairment	13,705	12,045
Total allowance for loan losses	15,930	12,869
Loans individually evaluated for impairment	33,945	23,261
Loans collectively evaluated for impairment	532,785	596,250
Total loans outstanding	566,730	619,511
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	1,348	1,253
Provision for loan losses	116	719
Recoveries	102	136
Charge-offs	(328)	(834)
Ending balance	1,238	1,274
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance individually evaluated for impairment	208	71
Allowance collectively evaluated for impairment	1,030	1,203
Total allowance for loan losses	1,238	1,274
Loans individually evaluated for impairment	1,704	1,445
Loans collectively evaluated for impairment	275,983	285,993
Total loans outstanding	277,687	287,438
Commitments and Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	12,597	14,060
Provision for loan losses	5	2,116
Recoveries	0	0
Charge-offs	0	0
Ending balance	12,602	16,176
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance individually evaluated for impairment	0	0
Allowance collectively evaluated for impairment	12,602	16,176
Total allowance for loan losses	12,602	16,176
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	0	0
Total loans outstanding	$ 0	$ 0