LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Allowance for Loan Losses) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Beginning balance	$ 75,907	$ 74,258
PROVISION FOR LOAN LOSSES	0us-gaap_ProvisionForLoanAndLeaseLosses	0us-gaap_ProvisionForLoanAndLeaseLosses
Recoveries	647	1,641
Charge-offs	(1,189)	(1,528)
Ending balance	75,365	74,371
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment	2,606	4,693
Allowance collectively evaluated for impairment	72,759	69,678
Total allowance for loan losses	75,365	74,371
Loans individually evaluated for impairment	40,085	53,009
Loans collectively evaluated for impairment	4,069,059	3,469,903
Financing Receivable, Acquired with Deteriorated Credit Quality	5,674
Total loans outstanding	4,114,818	3,522,912	3,833,820
Commercial real estate [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Beginning balance	18,784	16,759
PROVISION FOR LOAN LOSSES	305	595
Recoveries	14	296
Charge-offs	0	(238)
Ending balance	19,103	17,412
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment	643	574
Allowance collectively evaluated for impairment	18,460	16,838
Total allowance for loan losses	19,103	17,412
Loans individually evaluated for impairment	8,958	10,063
Loans collectively evaluated for impairment	1,550,691	1,241,036
Financing Receivable, Acquired with Deteriorated Credit Quality	4,575
Total loans outstanding	1,564,224	1,251,099	1,403,725
Multifamily real estate [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Beginning balance	4,562	5,306
PROVISION FOR LOAN LOSSES	(161)	346
Recoveries	0	0
Charge-offs	0	0
Ending balance	4,401	5,652
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment	84	1,059
Allowance collectively evaluated for impairment	4,317	4,593
Total allowance for loan losses	4,401	5,652
Loans individually evaluated for impairment	1,359	5,726
Loans collectively evaluated for impairment	207,328	147,277
Financing Receivable, Acquired with Deteriorated Credit Quality	0
Total loans outstanding	208,687	153,003	167,524
Construction and Land [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Beginning balance	23,545	17,640
PROVISION FOR LOAN LOSSES	745	748
Recoveries	108	232
Charge-offs	0	0
Ending balance	24,398	18,620
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment	808	1,521
Allowance collectively evaluated for impairment	23,590	17,099
Total allowance for loan losses	24,398	18,620
Loans individually evaluated for impairment	11,573	10,133
Loans collectively evaluated for impairment	419,390	368,641
Financing Receivable, Acquired with Deteriorated Credit Quality	0
Total loans outstanding	430,963	378,774	411,006
Commercial business [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Beginning balance	12,043	11,773
PROVISION FOR LOAN LOSSES	778	35
Recoveries	178	293
Charge-offs	(107)	(738)
Ending balance	12,892	11,363
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment	78	159
Allowance collectively evaluated for impairment	12,814	11,204
Total allowance for loan losses	12,892	11,363
Loans individually evaluated for impairment	725	1,040
Loans collectively evaluated for impairment	775,854	715,506
Financing Receivable, Acquired with Deteriorated Credit Quality	0
Total loans outstanding	776,579	716,546	723,964
Agricultural Business/Farmland [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Beginning balance	2,821	2,841
PROVISION FOR LOAN LOSSES	1,434	(555)
Recoveries	295	350
Charge-offs	(818)	0
Ending balance	3,732	2,636
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment	3	0
Allowance collectively evaluated for impairment	3,729	2,636
Total allowance for loan losses	3,732	2,636
Loans individually evaluated for impairment	289	0
Loans collectively evaluated for impairment	208,346	208,817
Financing Receivable, Acquired with Deteriorated Credit Quality	0
Total loans outstanding	208,635	208,817	238,499
One- to four-family [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Beginning balance	8,447	11,486
PROVISION FOR LOAN LOSSES	(237)	(382)
Recoveries	6	188
Charge-offs	(75)	(379)
Ending balance	8,141	10,913
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment	925	1,292
Allowance collectively evaluated for impairment	7,216	9,621
Total allowance for loan losses	8,141	10,913
Loans individually evaluated for impairment	16,036	24,959
Loans collectively evaluated for impairment	535,295	492,662
Financing Receivable, Acquired with Deteriorated Credit Quality	1,092
Total loans outstanding	552,423	517,621	539,894
Consumer [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Beginning balance	483	1,335
PROVISION FOR LOAN LOSSES	245	(532)
Recoveries	46	282
Charge-offs	(189)	(173)
Ending balance	585	912
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment	65	88
Allowance collectively evaluated for impairment	520	824
Total allowance for loan losses	585	912
Loans individually evaluated for impairment	1,145	1,088
Loans collectively evaluated for impairment	372,155	295,964
Financing Receivable, Acquired with Deteriorated Credit Quality	7
Total loans outstanding	373,307	297,052	349,208
Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Beginning balance	5,222	7,118
PROVISION FOR LOAN LOSSES	(3,109)	(255)
Recoveries	0	0
Charge-offs	0	0
Ending balance	2,113	6,863
Financing Receivable, Allowance for Loan Losses, Additional Information [Abstract]
Allowance individually evaluated for impairment	0	0
Allowance collectively evaluated for impairment	2,113	6,863
Total allowance for loan losses	2,113	6,863
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	0	0
Financing Receivable, Acquired with Deteriorated Credit Quality	0
Total loans outstanding	$ 0	$ 0

Loans Receivable, Including Loans Held-for-sale, Gross

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The balance of financing receivables that were acquired with deteriorated credit quality.

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A valuation allowance for financing receivables that are expected to be uncollectible.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of direct write-downs of financing receivables charged against the allowance.

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The balance of financing receivables that were collectively evaluated for impairment.

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Amount of expense related to estimated loss from loan and lease transactions.

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