FAIR VALUE OF FINANCIAL INSTRUMENTS - Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financial Assets [Abstract]
Securities held-to-maturity	$ 495,986	$ 505,759
Carrying Amount
Financial Assets [Abstract]
Cash and due from banks	358,824	169,297
Securities held-to-maturity	600,291	585,798
Loans held for investment, net	10,777,696	10,482,145
Accrued interest receivable	53,608	48,561
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,194,247	9,139,043
Certificates of Deposits ("CDs")	1,442,299	1,115,364
FHLBNY Advances	1,123,000	1,131,000
Subordinated debt, net	200,218	200,283
Other short-term borrowings		1,360
Accrued interest payable	19,948	5,323
Fair Value
Financial Assets [Abstract]
Cash and due from banks	358,824	169,297
Securities held-to-maturity	495,986	505,759
Loans held for investment, net	10,255,764	10,005,121
Accrued interest receivable	53,608	48,561
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,194,247	9,139,043
Certificates of Deposits ("CDs")	1,433,548	1,096,808
FHLBNY Advances	1,119,564	1,131,217
Subordinated debt, net	162,218	180,583
Other short-term borrowings		1,360
Accrued interest payable	19,948	5,323
Level 1 Inputs | Fair Value
Financial Assets [Abstract]
Cash and due from banks	358,824	169,297
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,194,247	9,139,043
Other short-term borrowings		1,360
Level 2 Inputs | Fair Value
Financial Assets [Abstract]
Securities held-to-maturity	495,986	505,759
Accrued interest receivable	5,525	6,105
Financial Liabilities [Abstract]
Certificates of Deposits ("CDs")	1,433,548	1,096,808
FHLBNY Advances	1,119,564	1,131,217
Subordinated debt, net	162,218	180,583
Accrued interest payable	19,948	5,323
Level 3 Inputs | Fair Value
Financial Assets [Abstract]
Loans held for investment, net	10,255,764	10,005,121
Accrued interest receivable	$ 48,083	$ 42,456