LOANS AND LEASES (Schedule of Loans Outstanding, by Type of Loan) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Total loans	$ 5,486,721	$ 5,285,246
Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	100.00%	100.00%
Unallocated Financing Receivables [Member]
Total loans	$ 265	$ 304
Unallocated Financing Receivables [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	0.01%	0.01%
Primary Residential Mortgage [Member] | Residential Portfolio Segment [Member]
Total loans	$ 585,295	$ 525,756
Primary Residential Mortgage [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	10.67%	9.95%
Multifamily Property [Member] | Residential Portfolio Segment [Member]
Total loans	$ 1,871,853	$ 1,863,915
Multifamily Property [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	34.11%	35.27%
Commercial Mortgage [Member] | Commercial Real Estate Portfolio Segment [Member]
Total loans	$ 622,469	$ 624,625
Commercial Mortgage [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	11.34%	11.82%
Commercial Loans Including Equipment Financing [Member] | Commercial Real Estate Portfolio Segment [Member]
Total loans	$ 2,300,398	$ 2,194,094
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)	41.93%	41.51%
Construction [Member] | Commercial Portfolio Segment [Member]
Total loans	$ 14,803	$ 4,042
Construction [Member] | Commercial Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	0.27%	0.07%
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member]
Total loans	$ 34,411	$ 34,496
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)	0.63%	0.65%
Consumer Loans, Including Home Equity Loans [Member] | Consumer and Other Loans [Member]
Total loans	$ 57,227	$ 38,014
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)	1.04%	0.72%