LOANS HELD FOR INVESTMENT, NET - Past Due Status (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	$ 10,116,941	$ 9,244,661
Non-accrual	41,081	40,307
Aggregate outstanding balance	2,800	3,000
Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	72,906	116,696
30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	19,454	61,242
60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	9,590	12,146
Loans 90 Days or More Past Due and Still Accruing Interest
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	2,781	3,001
Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	10,044,035	9,127,965
Total real estate loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	9,195,863	8,294,204
Non-accrual	11,549	12,676
Total real estate loans | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	34,706	77,109
Total real estate loans | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	15,336	57,385
Total real estate loans | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	7,821	5,103
Total real estate loans | Loans 90 Days or More Past Due and Still Accruing Interest
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans		1,945
Total real estate loans | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	9,161,157	8,217,095
One-to-four family residential and cooperative/condominium apartment
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	722,081	669,282
Non-accrual	3,219	7,623
One-to-four family residential and cooperative/condominium apartment | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,856	13,739
One-to-four family residential and cooperative/condominium apartment | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	496	3,294
One-to-four family residential and cooperative/condominium apartment | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	141	877
One-to-four family residential and cooperative/condominium apartment | Loans 90 Days or More Past Due and Still Accruing Interest
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans		1,945
One-to-four family residential and cooperative/condominium apartment | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	718,225	655,543
Multifamily residential and residential mixed-use
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,968,244	3,356,346
Multifamily residential and residential mixed-use | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,713	34,322
Multifamily residential and residential mixed-use | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,713	30,983
Multifamily residential and residential mixed-use | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0	3,339
Multifamily residential and residential mixed-use | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,963,531	3,322,024
Commercial real estate ("CRE")
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,264,519	3,945,948
Non-accrual	7,673	5,053
Commercial real estate ("CRE") | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	25,480	29,048
Commercial real estate ("CRE") | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	10,127	23,108
Commercial real estate ("CRE") | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	7,680	887
Commercial real estate ("CRE") | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,239,039	3,916,900
Acquisition, development, and construction
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	241,019	322,628
Non-accrual	657
Acquisition, development, and construction | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	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	240,362	322,628
Commercial and Industrial ("C&I") Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	912,151	933,559
Non-accrual	29,532	27,266
Commercial and Industrial ("C&I") Loans | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	38,055	39,115
Commercial and Industrial ("C&I") Loans | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,973	3,753
Commercial and Industrial ("C&I") Loans | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	1,769	7,040
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	2,781	1,056
Commercial and Industrial ("C&I") Loans | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	874,096	894,444
Other Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	8,927	16,898
Non-accrual	0	365
Other Loans | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	145	472
Other Loans | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	145	104
Other Loans | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0	3
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	$ 8,782	$ 16,426