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LOANS HELD FOR INVESTMENT, NET - Loan Categories (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Loans held for investment, net:
Total	$ 10,870,030		$ 10,869,328
Fair value hedge basis point adjustments	842		2,615
Total loans, net of fair value hedge basis point adjustments	10,870,872		10,871,943
Allowance for credit losses	(93,189)		(88,751)
Total loans held for investment, net	10,777,683		10,783,192
Business Loans
Loans held for investment, net:
Total	2,901,948		2,725,726
Allowance for credit losses	(42,965)	$ (43,915)	(42,898)	$ (37,115)	$ (35,981)	$ (35,962)
One-to-Four Family Residential and Cooperative/Condominium Apartment
Loans held for investment, net:
Total	998,446		951,528
Allowance for credit losses	(9,567)	(9,745)	(9,501)	(7,305)	(6,973)	(6,813)
Multifamily Residential and Residential Mixed-Use
Loans held for investment, net:
Total	3,693,425		3,820,283
Allowance for credit losses	(13,667)	(13,087)	(11,946)	(12,357)	(11,171)	(7,237)
Non-Owner-Occupied Commercial Real Estate
Loans held for investment, net:
Total	3,128,120		3,230,535
Allowance for credit losses	(24,326)	(21,075)	(21,876)	(18,340)	(19,445)	(19,623)
Acquisition, development, and construction ("ADC")
Loans held for investment, net:
Total	141,755		136,172
Allowance for credit losses	(2,380)	(2,360)	(2,323)	(2,455)	(2,322)	(1,989)
Other Loans
Loans held for investment, net:
Total	6,336		5,084
Allowance for credit losses	$ (284)	$ (273)	$ (207)	$ (240)	$ (176)	$ (119)