FINANCIAL INSTRUMENTS WITH OFF-BALANCE-SHEET RISK: (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Other Commitments			$ 120,111,000	$ 119,108,000
TOTAL			823,422,000	716,382,000
Minimum
Loss Contingencies [Line Items]
Loans and Leases Receivable, Commitments, Fixed Rates	$ 0.0325	$ 0.0325
Maximum
Loss Contingencies [Line Items]
Loans and Leases Receivable, Commitments, Fixed Rates	$ 0.0600	$ 0.0600
Home Equity
Loss Contingencies [Line Items]
TOTAL			92,346,000	88,672,000
Commercial Operating Lines
Loss Contingencies [Line Items]
TOTAL			610,965,000	508,602,000
Commercial letters of credit
Loss Contingencies [Line Items]
TOTAL			$ 7,042,000	$ 3,601,000