FAIR VALUE OF FINANCIAL INSTRUMENTS, Balance Sheet Groupings (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Carrying Amount [Member]
Financial Assets [Abstract]
Cash and due from banks	$ 117,013	$ 155,488
Loans, net	5,401,890	5,312,097
Accrued interest receivable	27,506	18,891
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,044,858	2,709,756
Certificates of Deposits ("CDs")	1,393,554	1,572,869
Escrow and other deposits	87,646	76,481
FHLBNY Advances	1,017,300	1,092,250
Subordinated debt, net	113,979	113,906
Other borrowings		110,000
Accrued interest payable	1,961	4,570
Fair Value [Member]
Financial Assets [Abstract]
Cash and due from banks	117,013	155,488
Loans, net	5,413,499	5,301,708
Accrued interest receivable	27,506	18,891
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,044,858	2,709,756
Certificates of Deposits ("CDs")	1,400,677	1,576,706
Escrow and other deposits	87,646	76,481
FHLBNY Advances	1,026,525	1,093,964
Subordinated debt, net	109,379	114,769
Other borrowings		110,000
Accrued interest payable	1,961	4,570
Fair Value [Member] | Level 1 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	117,013	155,488
Loans, net	0	0
Accrued interest receivable	0	0
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,044,858	2,709,756
Certificates of Deposits ("CDs")	0	0
Escrow and other deposits	87,646	76,481
FHLBNY Advances	0	0
Subordinated debt, net	0	0
Other borrowings		110,000
Accrued interest payable	0	0
Fair Value [Member] | Level 2 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	0	0
Loans, net	0	0
Accrued interest receivable	1,559	1,674
Financial Liabilities [Abstract]
Savings, money market and checking accounts	0	0
Certificates of Deposits ("CDs")	1,400,677	1,576,706
Escrow and other deposits	0	0
FHLBNY Advances	1,026,525	1,093,964
Subordinated debt, net	109,379	114,769
Other borrowings		0
Accrued interest payable	1,961	4,570
Fair Value [Member] | Level 3 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	0	0
Loans, net	5,413,499	5,301,708
Accrued interest receivable	25,947	17,217
Financial Liabilities [Abstract]
Savings, money market and checking accounts	0	0
Certificates of Deposits ("CDs")	0	0
Escrow and other deposits	0	0
FHLBNY Advances	0	0
Subordinated debt, net	0	0
Other borrowings		0
Accrued interest payable	$ 0	$ 0