RETIREMENT PLANS: (Details 11) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,355	$ 1,300	$ 1,218
Interest cost	2,632	3,116	3,465
Recognized actuarial loss	(2,943)	6,845
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)
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
Postretirement Health Coverage [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	43	38	34
Interest cost	103	125	146
Amortization of net actuarial loss (gain)	0	0	(16)
Net periodic pension cost	146	163	164
Net loss (gain) during the period	(53)	238	626
Amortization of prior service cost	0	0	16
Total recognized in other comprehensive income (loss)	(53)	238	642
Total recognized net periodic pension cost and other comprehensive income	$ 93	$ 401	$ 806