FINANCIAL INSTRUMENTS WITH OFF-BALANCE-SHEET RISK: (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Other Commitments			$ 83,786,000	$ 66,408,000
TOTAL			387,701,000	390,347,000
Minimum
Loss Contingencies [Line Items]
Loans and Leases Receivable, Commitments, Fixed Rates	$ 0.0400	$ 0.0325
Maximum
Loss Contingencies [Line Items]
Loans and Leases Receivable, Commitments, Fixed Rates	$ 0.0725	$ 0.0700
Commercial Operating Lines
Loss Contingencies [Line Items]
TOTAL			246,855,000	268,577,000
Commercial letters of credit
Loss Contingencies [Line Items]
TOTAL			5,012,000	5,673,000
Home Equity
Loss Contingencies [Line Items]
TOTAL			$ 57,060,000	$ 55,362,000