RETIREMENT PLANS: (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Retirement Benefits [Abstract]
Service cost - benefits earned	$ 1,355	$ 1,300	$ 1,218
Interest cost on projected benefit obligation	2,632	3,116	3,465
Expected return on plan assets	(4,713)	(4,198)	(3,585)
Net amortization and deferral	2,072	1,968	1,558
Net periodic pension cost	1,346	2,186	2,656
Net loss (gain) during the period	(5,883)	3,188	6,362
Amortization of prior service cost	1	1	1
Amortization of unrecognized (gain) loss	(2,072)	(1,967)	(1,558)
Total recognized in other comprehensive (income) loss	7,956	(1,220)	(4,803)
Total recognized net periodic pension cost and other comprehensive income	$ (6,610)	$ 3,406	$ 7,459