LOANS HELD FOR INVESTMENT, NET - Past Due Status (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	$ 10,731,845	$ 10,566,831
Non-accrual	31,544	34,237
Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	51,608	58,496
30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	18,693	23,517
60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	1,371	742
Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	10,680,237	10,508,335
Total real estate loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	9,649,743	9,487,440
Non-accrual	11,533	12,192
Total real estate loans | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	27,729	31,884
Total real estate loans | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	15,061	19,692
Total real estate loans | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	1,135
Total real estate loans | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	9,622,014	9,455,556
One-to-four family residential and cooperative/condominium apartment
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	799,321	773,321
Non-accrual	2,808	3,203
One-to-four family residential and cooperative/condominium apartment | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	9,844	3,889
One-to-four family residential and cooperative/condominium apartment | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	6,617	686
One-to-four family residential and cooperative/condominium apartment | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	419
One-to-four family residential and cooperative/condominium apartment | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	789,477	769,432
Multifamily residential and residential mixed-use
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,118,439	4,026,826
Multifamily residential and residential mixed-use | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,841	4,817
Multifamily residential and residential mixed-use | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,841	4,817
Multifamily residential and residential mixed-use | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Multifamily residential and residential mixed-use | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,114,598	4,022,009
Commercial real estate ("CRE")
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,510,968	4,457,630
Non-accrual	8,068	8,332
Commercial real estate ("CRE") | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	13,387	22,521
Commercial real estate ("CRE") | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,603	14,189
Commercial real estate ("CRE") | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	716
Commercial real estate ("CRE") | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,497,581	4,435,109
Acquisition, development, and construction
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	221,015	229,663
Non-accrual	657	657
Acquisition, development, and construction | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	657	657
Acquisition, development, and construction | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Acquisition, development, and construction | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Acquisition, development, and construction | Loans 90 Days or More Past Due and Still Accruing Interest
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Acquisition, development, and construction | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	220,358	229,006
Commercial and Industrial ("C&I") Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	1,074,930	1,071,712
Non-accrual	19,912	21,946
Commercial and Industrial ("C&I") Loans | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	23,548	26,248
Commercial and Industrial ("C&I") Loans | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,403	3,561
Commercial and Industrial ("C&I") Loans | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	233	741
Commercial and Industrial ("C&I") Loans | Loans 90 Days or More Past Due and Still Accruing Interest
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Commercial and Industrial ("C&I") Loans | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	1,051,382	1,045,464
Other Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	7,172	7,679
Non-accrual	99	99
Other Loans | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	331	364
Other Loans | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	229	264
Other Loans | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3	1
Other Loans | Loans 90 Days or More Past Due and Still Accruing Interest
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Other Loans | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	$ 6,841	$ 7,315