LOANS (Schedule of Loans Outstanding, by Classification) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Total loans	$ 3,027,701	$ 2,913,242
Loans and Finance Receivables [Member]
Total loans (in percent)	100.00%	100.00%
Unallocated Financing Receivables [Member]
Total loans	$ 443	$ 500
Unallocated Financing Receivables [Member] | Loans and Finance Receivables [Member]
Total loans (in percent)	0.01%	0.02%
Residential Mortgage [Member] | Residential Portfolio Segment [Member]
Total loans	$ 469,084	$ 470,869
Residential Mortgage [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables [Member]
Total loans (in percent)	15.49%	16.16%
Multifamily Property [Member] | Residential Portfolio Segment [Member]
Total loans	$ 1,489,708	$ 1,416,775
Multifamily Property [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables [Member]
Total loans (in percent)	49.20%	48.63%
Commercial Mortgage [Member] | Commercial Real Estate Portfolio Segment [Member]
Total loans	$ 414,677	$ 413,118
Commercial Mortgage [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans and Finance Receivables [Member]
Total loans (in percent)	13.70%	14.18%
Commercial Loans [Member] | Commercial Portfolio Segment [Member]
Total loans	$ 554,871	$ 512,886
Commercial Loans [Member] | Commercial Portfolio Segment [Member] | Loans and Finance Receivables [Member]
Total loans (in percent)	18.33%	17.60%
Construction Loans [Member]
Total loans	$ 1,392	$ 1,401
Construction Loans [Member] | Loans and Finance Receivables [Member]
Total loans (in percent)	0.05%	0.05%
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member]
Total loans	$ 53,328	$ 52,649
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables [Member]
Total loans (in percent)	1.76%	1.81%
Consumer Loans, Including Home Equity Loans [Member] | Consumer and Other [Member]
Total loans	$ 44,198	$ 45,044
Consumer Loans, Including Home Equity Loans [Member] | Consumer and Other [Member] | Loans and Finance Receivables [Member]
Total loans (in percent)	1.46%	1.55%