LOANS HELD FOR INVESTMENT, NET - Loan Categories (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Loans held for investment, net:
Total Loans	$ 10,876,415		$ 10,566,831
Allowance for loan losses	(75,646)		(83,507)
Total loans held for investment, net	10,800,769		10,483,324
Business Loan Portfolio Segment [Member]
Loans held for investment, net:
Total Loans	2,250,108		2,211,857
Allowance for loan losses	(39,700)	$ (43,879)	(47,029)	$ (45,128)	$ (43,728)	$ (62,366)
One-to-four family residential and cooperative/condominium apartment
Loans held for investment, net:
Total Loans	855,980		773,321
Allowance for loan losses	(6,419)	(6,012)	(5,969)	(4,514)	(4,528)	(5,932)
Multifamily residential and residential mixed-use
Loans held for investment, net:
Total Loans	4,132,358		4,026,826
Allowance for loan losses	(8,190)	(7,613)	(8,360)	(7,003)	(7,061)	(7,816)
Non-owner Occupied Commercial Real Estate Portfolio Segment [Member]
Loans held for investment, net:
Total Loans	3,406,232		3,317,485
Allowance for loan losses	(18,440)	(18,076)	(20,153)	(18,707)	(19,180)	(2,131)
Non-owner Occupied Commercial Real Estate Portfolio Segment [Member] | Total real estate loans
Loans held for investment, net:
Total Loans	3,406,232		3,317,485
Acquisition, development, and construction ("ADC")
Loans held for investment, net:
Total Loans	225,580		229,663
Allowance for loan losses	(2,558)	(2,515)		(3,788)	(4,758)
Acquisition, development, and construction ("ADC") | Total real estate loans
Loans held for investment, net:
Allowance for loan losses	(2,558)		(1,723)	(3,788)		(4,857)
Other Loans
Loans held for investment, net:
Total Loans	6,157		7,679
Allowance for loan losses	$ (339)	$ (240)	$ (273)	$ (286)	$ (360)	$ (751)