FAIR VALUE OF FINANCIAL INSTRUMENTS, Balance Sheet Groupings (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financial Assets [Abstract]
TRUP CDOs		$ 7,296
Carrying Amount [Member]
Financial Assets [Abstract]
Cash and due from banks	$ 173,060	113,503
TRUP CDOs		5,378
Loans, net	5,956,751	5,615,886
Accrued interest receivable	16,793	15,647
FHLBNY capital stock	61,833	44,444
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,345,693	3,346,961
Certificates of Deposit ("CDs")	1,025,500	1,048,465
Escrow and other deposits	117,765	103,001
FHLBNY Advances	1,217,500	831,125
Subordinated debt, net	113,575
Trust preferred securities payable		70,680
Accrued interest payable	2,759	2,080
Fair Value [Member]
Financial Assets [Abstract]
Cash and due from banks	173,060	113,503
TRUP CDOs		7,296
Loans, net	5,946,931	5,609,034
Accrued interest receivable	16,793	15,647
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,345,693	3,346,961
Certificates of Deposit ("CDs")	1,027,592	1,054,131
Escrow and other deposits	117,765	103,001
FHLBNY Advances	1,215,706	831,951
Subordinated debt, net	115,875
Trust preferred securities payable		69,973
Accrued interest payable	2,759	2,080
Fair Value [Member] | Level 1 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	173,060	113,503
TRUP CDOs		0
Loans, net	0	0
Accrued interest receivable	0	0
Financial Liabilities [Abstract]
Savings, money market and checking accounts	3,345,693	3,346,961
Certificates of Deposit ("CDs")	0	0
Escrow and other deposits	117,765	103,001
FHLBNY Advances	0	0
Subordinated debt, net	0
Trust preferred securities payable		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
Loans, net	0	0
Accrued interest receivable	58	11
Financial Liabilities [Abstract]
Savings, money market and checking accounts	0	0
Certificates of Deposit ("CDs")	1,027,592	1,054,131
Escrow and other deposits	0	0
FHLBNY Advances	1,215,706	831,951
Subordinated debt, net	115,875
Trust preferred securities payable		69,973
Accrued interest payable	2,759	2,080
Fair Value [Member] | Level 3 Inputs [Member]
Financial Assets [Abstract]
Cash and due from banks	0	0
TRUP CDOs		7,296
Loans, net	5,946,931	5,609,034
Accrued interest receivable	16,735	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, net	0
Trust preferred securities payable		0
Accrued interest payable	$ 0	$ 0