LOANS HELD FOR INVESTMENT, NET - Allowance for Credit Losses Activity (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	$ 71,743
Provision (recovery) for credit losses	5,210	$ (3,648)
Allowance for credit losses, Ending balance	76,068		$ 71,743
Non-accrual with No Allowance	15,563		3,780
Non-accrual with Allowance	19,264		25,319
Reserve	13,247		14,202
Interest income on non-accrual loans held for investment
Interest income on non-accrual loans	0	0
Business loans
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	35,962	47,029	47,029
Provision (recovery) for credit losses	734	(1,608)
Charge-offs	(796)	(2,029)	(15,364)
Recoveries	81	487
Allowance for credit losses, Ending balance	35,981	43,879	35,962
Non-accrual with No Allowance	3,310		3,780
Non-accrual with Allowance	14,903		14,794
Reserve	12,800		13,127
One-to-four family residential and cooperative/condominium apartment
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	6,813	5,969	5,969
Provision (recovery) for credit losses	160	43
Charge-offs			(14)
Allowance for credit losses, Ending balance	6,973	6,012	6,813
Non-accrual with Allowance	3,689		3,248
Reserve	145		133
Multifamily residential and residential mixed-use
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	7,237	8,360	8,360
Provision (recovery) for credit losses	3,934	(747)
Charge-offs			(2)
Allowance for credit losses, Ending balance	11,171	7,613	7,237
Non-owner-occupied commercial real estate
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	19,623	20,153	20,153
Provision (recovery) for credit losses	(178)	(2,077)
Allowance for credit losses, Ending balance	19,445	18,076	19,623
Non-accrual with Allowance	15		6,620
Reserve	15		636
Acquisition, development, and construction ("ADC")
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	1,989	1,723	1,723
Provision (recovery) for credit losses	333	792
Allowance for credit losses, Ending balance	2,322	2,515	1,989
Non-accrual with No Allowance	12,253
Non-accrual with Allowance	657		657
Reserve	287		305
Other Loans
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	119	273	273
Provision (recovery) for credit losses	81	(34)
Charge-offs	(30)	(1)
Recoveries	6	2
Allowance for credit losses, Ending balance	176	240	119
Includes other loans
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	71,743	83,507	83,507
Provision (recovery) for credit losses	5,064	(3,631)
Charge-offs	(826)	(2,030)
Recoveries	87	489
Allowance for credit losses, Ending balance	$ 76,068	$ 78,335	$ 71,743