FAIR VALUE OF FINANCIAL INSTRUMENTS - Balance Sheet Groupings (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financial Assets [Abstract]
Securities held-to-maturity	$ 358,689	$ 177,354
Carrying Amount
Financial Assets [Abstract]
Cash and due from banks	432,994	393,722
Securities held-to-maturity	383,922	179,309
Loans held for investment, net	9,169,055	9,158,908
Accrued interest receivable	38,456	40,149
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,648,328	9,605,731
Certificates of Deposits ("CDs")	781,775	853,242
FHLBNY Advances	50,000	25,000
Subordinated debt, net	197,050	197,096
Other short-term borrowings	2,853	1,862
Accrued interest payable	1,611	870
Fair Value
Financial Assets [Abstract]
Cash and due from banks	432,994	393,722
Securities held-to-maturity	358,689	177,354
Loans held for investment, net	9,095,834	9,169,872
Accrued interest receivable	38,456	40,149
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,648,328	9,605,731
Certificates of Deposits ("CDs")	782,385	857,342
FHLBNY Advances	50,039	25,014
Subordinated debt, net	198,650	202,334
Other short-term borrowings	2,853	1,862
Accrued interest payable	1,611	870
Level 1 Inputs [Member] | Fair Value
Financial Assets [Abstract]
Cash and due from banks	432,994	393,722
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,648,328	9,605,731
Other short-term borrowings	2,853	1,862
Level 2 Inputs [Member] | Fair Value
Financial Assets [Abstract]
Securities held-to-maturity	358,689	177,354
Accrued interest receivable	4,483	4,481
Financial Liabilities [Abstract]
Certificates of Deposits ("CDs")	782,385	857,342
FHLBNY Advances	50,039	25,014
Subordinated debt, net	198,650	202,334
Accrued interest payable	1,611	870
Level 3 Inputs [Member] | Fair Value
Financial Assets [Abstract]
Loans held for investment, net	9,095,834	9,169,872
Accrued interest receivable	$ 33,973	$ 35,668