FAIR VALUE OF FINANCIAL INSTRUMENTS - Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Financial Assets [Abstract]
Securities held-to-maturity	$ 504,718	$ 516,930
Carrying Amount
Financial Assets [Abstract]
Cash and due from banks	370,852	457,547
Securities held-to-maturity	589,331	594,639
Loans held for investment, net	10,687,661	10,695,349
Accrued interest receivable	55,369	55,666
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,343,720	8,922,972
CDs	1,555,157	1,607,683
FHLBNY Advances	773,000	1,313,000
Subordinated debt, net	200,174	200,196
Accrued interest payable	20,121	17,298
Fair Value
Financial Assets [Abstract]
Cash and due from banks	370,852	457,547
Securities held-to-maturity	504,718	516,930
Loans held for investment, net	10,158,385	10,305,026
Accrued interest receivable	55,369	55,666
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,343,720	8,922,972
CDs	1,550,668	1,602,087
FHLBNY Advances	772,467	1,312,940
Subordinated debt, net	157,374	160,696
Accrued interest payable	20,121	17,298
Level 1 Inputs | Fair Value
Financial Assets [Abstract]
Cash and due from banks	370,852	457,547
Financial Liabilities [Abstract]
Savings, money market and checking accounts	9,343,720	8,922,972
Level 2 Inputs | Fair Value
Financial Assets [Abstract]
Securities held-to-maturity	504,718	516,930
Accrued interest receivable	5,798	6,593
Financial Liabilities [Abstract]
CDs	1,550,668	1,602,087
FHLBNY Advances	772,467	1,312,940
Subordinated debt, net	157,374	160,696
Accrued interest payable	20,121	17,298
Level 3 Inputs | Fair Value
Financial Assets [Abstract]
Loans held for investment, net	10,158,385	10,305,026
Accrued interest receivable	$ 49,571	$ 49,073