Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	6,970	7,825	20,910	23,474
Expected return on plan assets	(11,168)	(9,477)	(33,504)	(28,431)
Amortization of net loss	941	3,882	2,823	11,646
Net periodic benefit (income) loss	(3,257)	2,230	(9,771)	6,689
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	35	27	104	81
Interest cost	23	37	68	111
Expected return on plan assets	0	0	0	0
Amortization of net loss	31	43	93	129
Net periodic benefit (income) loss	$ 89	$ 107	$ 265	$ 321