LOANS (Schedule of Loans Outstanding, by Type of Loan) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Total loans	$ 3,927,931	$ 3,704,440
Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	100.00%	100.00%
Unallocated Financing Receivables [Member]
Total loans	$ 465	$ 402
Unallocated Financing Receivables [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	0.01%	0.01%
Residential Mortgage [Member] | Residential Portfolio Segment [Member]
Total loans	$ 571,570	$ 576,356
Residential Mortgage [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	14.55%	15.56%
Multifamily Property [Member] | Residential Portfolio Segment [Member]
Total loans	$ 1,135,805	$ 1,388,958
Multifamily Property [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	28.92%	37.49%
Commercial Mortgage [Member] | Commercial Real Estate Portfolio Segment [Member]
Total loans	$ 702,165	$ 626,656
Commercial Mortgage [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	17.88%	16.92%
Commercial Loans Including Equipment Financing [Member] | Commercial Real Estate Portfolio Segment [Member]
Total loans	$ 1,397,057	$ 958,294
Commercial Loans Including Equipment Financing [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	35.57%	25.87%
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member]
Total loans	$ 62,191	$ 67,497
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	1.58%	1.82%
Consumer Loans, Including Home Equity Loans [Member] | Consumer and Other Loans [Member]
Total loans	$ 58,678	$ 86,277
Consumer Loans, Including Home Equity Loans [Member] | Consumer and Other Loans [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	1.49%	2.33%