LOANS HELD FOR INVESTMENT, NET - Loan Categories (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Loans held for investment, net:
Total	$ 10,763,265	$ 10,766,837
Fair value hedge basis point adjustments	1,318	6,591
Total loans, net of fair value hedge basis point adjustments	10,764,583	10,773,428
Allowance for credit losses	(76,068)	(71,743)
Total loans held for investment, net	10,688,515	10,701,685
Business loans
Loans held for investment, net:
Total	2,326,962	2,308,171
Allowance for credit losses	(35,981)	(35,962)	$ (43,879)	$ (47,029)
One-to-four family residential and cooperative/condominium apartment
Loans held for investment, net:
Total	873,335	887,555
Allowance for credit losses	(6,973)	(6,813)	(6,012)	(5,969)
Multifamily residential and residential mixed-use
Loans held for investment, net:
Total	3,996,548	4,017,176
Allowance for credit losses	(11,171)	(7,237)	(7,613)	(8,360)
Non-owner-occupied commercial real estate
Loans held for investment, net:
Total	3,385,898	3,379,667
Allowance for credit losses	(19,445)	(19,623)	(18,076)	(20,153)
Acquisition, development, and construction ("ADC")
Loans held for investment, net:
Total	175,352	168,513
Allowance for credit losses	(2,322)	(1,989)	(2,515)	(1,723)
Other Loans
Loans held for investment, net:
Total	5,170	5,755
Allowance for credit losses	$ (176)	$ (119)	$ (240)	$ (273)