LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ (155,521)	$ (149,643)	$ (141,465)	$ (132,099)
Financing Receivable, Credit Loss, Expense (Reversal)	8,563	11,097	8,158
Recoveries	5,681	2,788	3,921
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 8,366	$ 5,707	$ 2,713
Net loan charge-offs as a percent of average outstanding loans during the period	(0.02%)	(0.03%)	0.01%
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ (40,830)	$ (44,384)	$ (44,086)	(52,995)
Financing Receivable, Credit Loss, Expense (Reversal)	5,970	259	9,299
Recoveries	2,767	557	392
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 351	$ 0	$ 2
Net loan charge-offs as a percent of average outstanding loans during the period	0.02%	0.01%	0.00%
Multifamily Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ (10,308)	$ (9,326)	$ (7,734)	(7,043)
Financing Receivable, Credit Loss, Expense (Reversal)	982	1,592	691
Recoveries	0	0	0
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 0	$ 0	$ 0
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	0.00%	0.00%
Construction and Land [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ (29,038)	$ (28,095)	$ (29,171)	(27,294)
Financing Receivable, Credit Loss, Expense (Reversal)	1,093	16	1,523
Recoveries	0	29	384
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 150	$ 1,089	$ 30
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	(0.01%)	0.00%
Commercial business [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ (38,611)	$ (35,464)	$ (33,299)	(26,421)
Financing Receivable, Credit Loss, Expense (Reversal)	7,139	3,532	6,654
Recoveries	1,963	1,283	1,923
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 4,020	$ 2,650	$ 1,699
Net loan charge-offs as a percent of average outstanding loans during the period	(0.04%)	(0.01%)	0.00%
Agricultural Business [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ (5,727)	$ (3,865)	$ (3,475)	(3,190)
Financing Receivable, Credit Loss, Expense (Reversal)	1,558	808	148
Recoveries	304	146	475
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 0	$ 564	$ 42
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	0.00%	0.00%
One- to four-family residential [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ (20,807)	$ (19,271)	$ (14,729)	(8,205)
Financing Receivable, Credit Loss, Expense (Reversal)	1,365	4,354	6,343
Recoveries	171	230	181
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 0	$ 42	$ 0
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	0.00%	0.00%
Consumer [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ (10,200)	$ (9,238)	$ (8,971)	$ (6,951)
Financing Receivable, Credit Loss, Expense (Reversal)	2,396	1,086	2,394
Recoveries	476	543	566
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 1,910	$ 1,362	$ 940
Net loan charge-offs as a percent of average outstanding loans during the period	(0.01%)	(0.01%)	0.00%
Small Balance Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 5,955

Net loan charge-offs as a percent of average outstanding loans during the period

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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