LOANS HELD FOR INVESTMENT, NET - Past Due Status (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	$ 10,876,415	$ 10,566,831
Non-accrual	27,667	34,237
Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	52,198	58,496
30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	16,389	23,517
60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	8,142	742
Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	10,824,217	10,508,335
Business Loan Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	2,250,108	2,211,857
Non-accrual	23,470	27,787
Business Loan Portfolio Segment [Member] | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	35,049	34,389
Business Loan Portfolio Segment [Member] | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,616	5,861
Business Loan Portfolio Segment [Member] | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	6,963	741
Business Loan Portfolio Segment [Member] | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	2,215,059	2,177,468
One-to-four family residential and cooperative/condominium apartment
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	855,980	773,321
Non-accrual	3,305	3,203
One-to-four family residential and cooperative/condominium apartment | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	5,892	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	1,409	686
One-to-four family residential and cooperative/condominium apartment | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	1,178
One-to-four family residential and cooperative/condominium apartment | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	850,088	769,432
Multifamily residential and residential mixed-use
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,132,358	4,026,826
Non-accrual	0
Multifamily residential and residential mixed-use | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	6,465	4,817
Multifamily residential and residential mixed-use | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	6,465	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 | Loans 90 Days or More Past Due and Still Accruing Interest
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Multifamily residential and residential mixed-use | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	4,125,893	4,022,009
Non-owner Occupied Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,406,232	3,317,485
Non-owner Occupied Commercial Real Estate Portfolio Segment [Member] | Total real estate loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,406,232	3,317,485
Non-accrual	15	2,491
Non-owner Occupied Commercial Real Estate Portfolio Segment [Member] | Total real estate loans | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,849	14,380
Non-owner Occupied Commercial Real Estate Portfolio Segment [Member] | Total real estate loans | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,834	11,889
Non-owner Occupied Commercial Real Estate Portfolio Segment [Member] | Total real estate loans | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Non-owner Occupied Commercial Real Estate Portfolio Segment [Member] | Total real estate loans | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	3,402,383	3,303,105
Acquisition, development, and construction ("ADC")
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	225,580	229,663
Non-accrual	657	657
Acquisition, development, and construction ("ADC") | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	657	657
Acquisition, development, and construction ("ADC") | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Acquisition, development, and construction ("ADC") | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Acquisition, development, and construction ("ADC") | Loans 90 Days or More Past Due and Still Accruing Interest
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	0
Acquisition, development, and construction ("ADC") | Current
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	224,923	229,006
Other Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	6,157	7,679
Non-accrual	220	99
Other Loans | Total Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	286	364
Other Loans | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	65	264
Other Loans | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Loans	1	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	$ 5,871	$ 7,315