Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	5,597	6,970	16,791	20,910
Expected return on plan assets	(11,875)	(11,168)	(35,625)	(33,504)
Amortization of net loss	1,764	941	5,292	2,823
Net periodic benefit cost (income) loss	(4,514)	(3,257)	(13,542)	(9,771)
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	24	35	72	104
Interest cost	10	23	30	68
Expected return on plan assets	0	0	0	0
Amortization of net loss	47	31	141	93
Net periodic benefit cost (income) loss	$ 81	$ 89	$ 243	$ 265