LOANS RECEIVABLE AND THE ALLOWANCE FOR CREDIT LOSSES (Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	$ 125,471	$ 156,054	$ 132,099	$ 167,279
(Recapture)/provision for credit losses	3,144	(8,100)	(4,232)	(16,135)
Recoveries	587	593	1,581	2,105
Charge-offs	(500)	(538)	(746)	(5,240)
Allowance for loan losses, Ending balance	128,702	148,009	128,702	148,009
Commercial Real Estate
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	47,264	59,411	52,995	57,791
(Recapture)/provision for credit losses	(1,020)	794	(6,836)	6,153
Recoveries	129	147	216	171
Charge-offs	0	(3)	(2)	(3,766)
Allowance for loan losses, Ending balance	46,373	60,349	46,373	60,349
Multifamily Real Estate
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	7,183	4,367	7,043	3,893
(Recapture)/provision for credit losses	(277)	1,440	(137)	1,914
Recoveries	0	0	0	0
Charge-offs	0	0	0	0
Allowance for loan losses, Ending balance	6,906	5,807	6,906	5,807
Construction and Land
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	26,679	36,440	27,294	41,295
(Recapture)/provision for credit losses	260	(5,541)	(734)	(10,496)
Recoveries	0	0	384	100
Charge-offs	0	0	(5)	0
Allowance for loan losses, Ending balance	26,939	30,899	26,939	30,899
Commercial Business
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	26,655	31,411	26,421	35,007
(Recapture)/provision for credit losses	2,032	(779)	2,199	(4,565)
Recoveries	234	321	383	1,300
Charge-offs	(248)	(123)	(330)	(912)
Allowance for loan losses, Ending balance	28,673	30,830	28,673	30,830
Agricultural Business
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	2,586	4,617	3,190	4,914
(Recapture)/provision for credit losses	402	(1,367)	(320)	(1,664)
Recoveries	14	8	132	8
Charge-offs	0	(2)	0	(2)
Allowance for loan losses, Ending balance	3,002	3,256	3,002	3,256
One- to Four-Family Residential
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	8,109	7,988	8,205	9,913
(Recapture)/provision for credit losses	1,366	1,792	1,230	(246)
Recoveries	98	20	138	133
Charge-offs	0	0	0	0
Allowance for loan losses, Ending balance	9,573	9,800	9,573	9,800
Consumer
Financing Receivable, Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, Beginning balance	6,995	11,820	6,951	14,466
(Recapture)/provision for credit losses	381	(4,439)	366	(7,231)
Recoveries	112	97	328	393
Charge-offs	(252)	(410)	(409)	(560)
Allowance for loan losses, Ending balance	$ 7,236	$ 7,068	$ 7,236	$ 7,068