LOANS AND LEASES (Schedule of Loans Outstanding, by Type of Loan) (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2021	Dec. 31, 2020
Total loans		$ 4,568,833	$ 4,372,437
Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)		100.00%	100.00%
Unallocated Financing Receivables [Member]
Total loans		$ 206	$ 226
Unallocated Financing Receivables [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)		0.00%	0.01%
Residential Mortgage [Member] | Residential Portfolio Segment [Member]
Total loans		$ 500,207	$ 502,829
Residential Mortgage [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)		10.95%	11.50%
Multifamily Property [Member] | Residential Portfolio Segment [Member]
Total loans		$ 1,420,043	$ 1,126,946
Multifamily Property [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)		31.08%	25.77%
Commercial Mortgage [Member] | Commercial Real Estate Portfolio Segment [Member]
Total loans		$ 702,777	$ 691,294
Commercial Mortgage [Member] | Commercial Real Estate Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)		15.38%	15.81%
Commercial Loans Including Equipment Financing [Member] | Commercial Real Estate Portfolio Segment [Member]
Total loans	[1]	$ 1,846,728	$ 1,950,981
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)	[1]	40.42%	44.62%
Construction [Member] | Commercial Portfolio Segment [Member]
Total loans		$ 22,923	$ 12,600
Construction [Member] | Commercial Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)		0.50%	0.29%
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member]
Total loans		$ 44,060	$ 50,545
Home Equity Lines of Credit [Member] | Residential Portfolio Segment [Member] | Loans and Finance Receivables, Gross [Member] | Credit Concentration Risk [Member]
Total loans (in percent)		0.97%	1.15%
Consumer Loans, Including Home Equity Loans [Member] | Consumer and Other Loans [Member]
Total loans		$ 31,889	$ 37,016
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)		0.70%	0.85%

[1] Includes PPP loans of $84 million at June 30, 2021 and $196 million at December 31, 2020.