FAIR VALUE OF FINANCIAL INSTRUMENTS, Balance Sheet Groupings (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Assets [Abstract]
Investment securities held to maturity (TRUPS)	$ 6,805	$ 7,051
Carrying Amount [Member]
Assets [Abstract]
Cash and due from banks	89,927	64,154
Investment securities held to maturity (TRUPS)	5,319	5,242
Loans, net	5,190,208	4,678,262
Accrued interest receivable	14,896	13,486
FHLBNY capital stock	52,814	58,713
Liabilities [Abstract]
Savings, money market and checking accounts	2,745,744	2,325,463
Certificates of Deposit ("CDs")	1,034,522	858,847
Escrow and other deposits	92,290	77,130
FHLBNY Advances	1,017,125	1,166,725
Trust preferred securities payable	70,680	70,680
Accrued interest payable	2,156	2,259
Fair Value [Member]
Assets [Abstract]
Cash and due from banks	89,927	64,154
Investment securities held to maturity (TRUPS)	6,805	7,051
Loans, net	5,213,167	4,722,803
Accrued interest receivable	14,896	12,664
Liabilities [Abstract]
Savings, money market and checking accounts	2,745,744	2,325,463
Certificates of Deposit ("CDs")	1,043,354	865,581
Escrow and other deposits	92,964	77,130
FHLBNY Advances	1,026,682	1,170,274
Trust preferred securities payable	69,973	69,973
Accrued interest payable	2,156	2,259
Fair Value [Member] | Level 1 Inputs [Member]
Assets [Abstract]
Cash and due from banks	89,927	64,154
Investment securities held to maturity (TRUPS)	0	0
Loans, net	0	0
Accrued interest receivable	0	0
Liabilities [Abstract]
Savings, money market and checking accounts	2,745,744	2,325,463
Certificates of Deposit ("CDs")	0	0
Escrow and other deposits	92,964	77,130
FHLBNY Advances	0	0
Trust preferred securities payable	0	0
Accrued interest payable	0	0
Fair Value [Member] | Level 2 Inputs [Member]
Assets [Abstract]
Cash and due from banks	0	0
Investment securities held to maturity (TRUPS)	0	0
Loans, net	0	0
Accrued interest receivable	2	19
Liabilities [Abstract]
Savings, money market and checking accounts	0	0
Certificates of Deposit ("CDs")	1,043,254	865,581
Escrow and other deposits	0	0
FHLBNY Advances	1,026,682	1,170,274
Trust preferred securities payable	69,973	69,973
Accrued interest payable	2,156	2,259
Fair Value [Member] | Level 3 Inputs [Member]
Assets [Abstract]
Cash and due from banks	0	0
Investment securities held to maturity (TRUPS)	6,805	7,051
Loans, net	5,213,167	4,722,803
Accrued interest receivable	14,894	13,467
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