FAIR VALUE OF FINANCIAL INSTRUMENTS, Balance Sheet Groupings (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financial Assets [Abstract]
TRUP CDOs	$ 8,385	$ 7,296
Carrying Amount [Member]
Financial Assets [Abstract]
Cash and due from banks	110,044	113,503
TRUP CDOs	5,315	5,378
Loans, net	5,854,896	5,615,886
Accrued interest receivable	16,124	15,647
FHLBNY capital stock	50,961	44,444
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,521,854	3,346,961
Certificates of Deposit ("CDs")	896,626	1,048,465
Escrow and other deposits	91,196	103,001
FHLBNY Advances	944,575	831,125
Subordinated debt	113,545
Trust preferred securities payable	70,680	70,680
Accrued interest payable	2,289	2,080
Fair Value [Member]
Financial Assets [Abstract]
Cash and due from banks	110,044	113,503
TRUP CDOs	8,385	7,296
Loans, net	5,845,003	5,609,034
Accrued interest receivable	16,124	15,647
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,521,854	3,346,961
Certificates of Deposit ("CDs")	899,111	1,054,131
Escrow and other deposits	91,196	103,001
FHLBNY Advances	943,875	831,951
Subordinated debt	114,695
Trust preferred securities payable	70,680	69,973
Accrued interest payable	2,289	2,080
Fair Value [Member] | Level 1 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	110,044	113,503
TRUP CDOs	0	0
Loans, net	0	0
Accrued interest receivable	0	0
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,521,854	3,346,961
Certificates of Deposit ("CDs")	0	0
Escrow and other deposits	91,196	103,001
FHLBNY Advances	0	0
Subordinated debt	0
Trust preferred securities payable	70,680	0
Accrued interest payable	0	0
Fair Value [Member] | Level 2 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	0	0
TRUP CDOs	0	0
Loans, net	0	0
Accrued interest receivable	12	11
Financial Liabilities [Abstract]
Savings, money market and checking accounts	0	0
Certificates of Deposit ("CDs")	899,111	1,054,131
Escrow and other deposits	0	0
FHLBNY Advances	943,875	831,951
Subordinated debt	114,695
Trust preferred securities payable	0	69,973
Accrued interest payable	2,289	2,080
Fair Value [Member] | Level 3 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	0	0
TRUP CDOs	8,385	7,296
Loans, net	5,845,003	5,609,034
Accrued interest receivable	16,112	15,636
Financial Liabilities [Abstract]
Savings, money market and checking accounts	0	0
Certificates of Deposit ("CDs")	0	0
Escrow and other deposits	0	0
FHLBNY Advances	0	0
Subordinated debt	0
Trust preferred securities payable	0	0
Accrued interest payable	$ 0	$ 0