FAIR VALUE OF FINANCIAL INSTRUMENTS, Balance Sheet Groupings (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financial Assets [Abstract]
Investment securities held to maturity (TRUP CDOs)	$ 8,048	$ 7,296
Carrying Amount [Member]
Financial Assets [Abstract]
Cash and due from banks	87,834	113,503
Investment securities held to maturity (TRUP CDOs)	5,332	5,378
Loans, net	5,731,195	5,615,886
Accrued interest receivable	15,114	15,647
FHLBNY capital stock	41,411	44,444
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,538,368	3,346,961
Certificates of Deposit ("CDs")	970,114	1,048,465
Escrow and other deposits	135,817	103,001
FHLBNY Advances	763,725	831,125
Trust preferred securities payable	70,680	70,680
Accrued interest payable	2,097	2,080
Fair Value [Member]
Financial Assets [Abstract]
Cash and due from banks	87,834	113,503
Investment securities held to maturity (TRUP CDOs)	8,048	7,296
Loans, net	5,717,743	5,609,034
Accrued interest receivable	15,114	15,647
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,538,368	3,346,961
Certificates of Deposit ("CDs")	973,533	1,054,131
Escrow and other deposits	135,817	103,001
FHLBNY Advances	763,641	831,951
Trust preferred securities payable	70,327	69,973
Accrued interest payable	2,097	2,080
Fair Value [Member] | Level 1 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	87,834	113,503
Investment securities held to maturity (TRUP CDOs)	0	0
Loans, net	0	0
Accrued interest receivable	0	0
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,538,368	3,346,961
Certificates of Deposit ("CDs")	0	0
Escrow and other deposits	135,817	103,001
FHLBNY Advances	0	0
Trust preferred securities payable	0	0
Accrued interest payable	0	0
Fair Value [Member] | Level 2 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	0	0
Investment securities held to maturity (TRUP CDOs)	0	0
Loans, net	0	0
Accrued interest receivable	11	11
Financial Liabilities [Abstract]
Savings, money market and checking accounts	0	0
Certificates of Deposit ("CDs")	973,533	1,054,131
Escrow and other deposits	0	0
FHLBNY Advances	763,641	831,951
Trust preferred securities payable	70,327	69,973
Accrued interest payable	2,097	2,080
Fair Value [Member] | Level 3 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	0	0
Investment securities held to maturity (TRUP CDOs)	8,048	7,296
Loans, net	5,717,743	5,609,034
Accrued interest receivable	15,103	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
Trust preferred securities payable	0	0
Accrued interest payable	$ 0	$ 0