FAIR VALUE OF FINANCIAL INSTRUMENTS - Balance Sheet Groupings (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financial Assets [Abstract]
Securities held-to-maturity	$ 177,354	$ 0
Carrying Amount
Financial Assets [Abstract]
Cash and due from banks	393,722	243,603
Securities held-to-maturity	179,309
Loans held for investment, net	9,158,908	5,580,583
Accrued interest receivable	40,149	34,815
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,605,731	3,202,484
Certificates of Deposits ("CDs")	853,242	1,322,638
FHLBNY Advances	25,000	1,204,010
Subordinated debt, net	197,096	114,052
Other short-term borrowings	1,862	120,000
Accrued interest payable	870	1,734
Fair Value
Financial Assets [Abstract]
Cash and due from banks	393,722	243,603
Securities held-to-maturity	179,309
Loans held for investment, net	9,169,872	5,598,787
Accrued interest receivable	40,149	34,815
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,605,731	3,202,484
Certificates of Deposits ("CDs")	857,342	1,328,554
FHLBNY Advances	25,014	1,207,890
Subordinated debt, net	202,334	114,340
Other short-term borrowings	1,862	120,000
Accrued interest payable	870	1,734
Level 1 Inputs [Member] | Fair Value
Financial Assets [Abstract]
Cash and due from banks	393,722	243,603
Accrued interest receivable		2
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,605,731	3,202,484
Other short-term borrowings	1,862	120,000
Level 2 Inputs [Member] | Fair Value
Financial Assets [Abstract]
Securities held-to-maturity	179,309
Accrued interest receivable	4,481	1,584
Financial Liabilities [Abstract]
Certificates of Deposits ("CDs")	857,342	1,328,554
FHLBNY Advances	25,014	1,207,890
Subordinated debt, net	202,334	114,340
Accrued interest payable	870	1,734
Level 3 Inputs [Member] | Fair Value
Financial Assets [Abstract]
Loans held for investment, net	9,169,872	5,598,787
Accrued interest receivable	$ 35,668	$ 33,229