LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 167,279	$ 100,559	$ 96,485
Provision for Loan and Lease Losses	(33,112)	64,285	10,000
Recoveries	4,615	6,263	2,465
Charge-offs	(6,683)	(11,640)	(8,391)
Ending balance	$ 132,099	$ 167,279	$ 100,559
Net loan charge-offs as a percent of average outstanding loans during the period	(0.02%)	(0.05%)	(0.07%)
Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for Loan and Lease Losses		$ 7,812
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 57,791	30,591	$ 27,132
Provision for Loan and Lease Losses	(2,758)	31,643	4,121
Recoveries	1,729	275	476
Charge-offs	(3,767)	(1,854)	(1,138)
Ending balance	$ 52,995	$ 57,791	$ 30,591
Net loan charge-offs as a percent of average outstanding loans during the period	(0.02%)	(0.02%)	(0.01%)
Commercial Real Estate [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for Loan and Lease Losses		$ (2,864)
Multifamily Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 3,893	4,754	$ 3,818
Provision for Loan and Lease Losses	3,209	1,409	936
Recoveries	0	0	0
Charge-offs	(59)	(66)	0
Ending balance	$ 7,043	$ 3,893	$ 4,754
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	0.00%	0.00%
Multifamily Real Estate [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for Loan and Lease Losses		$ (2,204)
Construction and Land [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 41,295	22,994	$ 24,442
Provision for Loan and Lease Losses	(14,101)	15,781	(1,611)
Recoveries	100	105	208
Charge-offs	0	(100)	(45)
Ending balance	$ 27,294	$ 41,295	$ 22,994
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	0.00%	0.00%
Construction and Land [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for Loan and Lease Losses		$ 2,515
Commercial business [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 35,007	23,370	$ 19,438
Provision for Loan and Lease Losses	(8,621)	12,615	7,478
Recoveries	1,797	3,265	625
Charge-offs	(1,762)	(7,253)	(4,171)
Ending balance	$ 26,421	$ 35,007	$ 23,370
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	(0.04%)	(0.04%)
Commercial business [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for Loan and Lease Losses		$ 3,010
Agricultural Business [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 4,914	4,120	$ 3,778
Provision for Loan and Lease Losses	(1,573)	(87)	1,206
Recoveries	30	1,823	47
Charge-offs	(181)	(591)	(911)
Ending balance	$ 3,190	$ 4,914	$ 4,120
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	0.01%	(0.01%)
Agricultural Business [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for Loan and Lease Losses		$ (351)
One- to four-family residential [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 9,913	4,136	$ 4,714
Provision for Loan and Lease Losses	(1,907)	(1,679)	(1,053)
Recoveries	199	467	561
Charge-offs	0	(136)	(86)
Ending balance	$ 8,205	$ 9,913	$ 4,136
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	0.00%	0.01%
One- to four-family residential [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for Loan and Lease Losses		$ 7,125
Consumer [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 14,466	8,202	$ 7,972
Provision for Loan and Lease Losses	(7,361)	4,603	1,722
Recoveries	760	328	548
Charge-offs	(914)	(1,640)	(2,040)
Ending balance	$ 6,951	$ 14,466	$ 8,202
Net loan charge-offs as a percent of average outstanding loans during the period	0.00%	(0.01%)	(0.02%)
Consumer [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for Loan and Lease Losses		$ 2,973
Unallocated [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 0	2,392	$ 5,191
Provision for Loan and Lease Losses	0	0	(2,799)
Recoveries	0	0	0
Charge-offs	0	0	0
Ending balance	$ 0	0	$ 2,392
Unallocated [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for Loan and Lease Losses		$ (2,392)

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

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- Definition

Amount of increase in allowance for credit loss on financing receivable from recovery.

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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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

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