Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 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	11,194	13,940
Expected return on plan assets	(11,875)	(11,168)	(23,750)	(22,336)
Amortization of net loss	1,764	941	3,528	1,882
Net periodic benefit cost (income) loss	(4,514)	(3,257)	(9,028)	(6,514)
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	24	35	48	69
Interest cost	10	23	20	45
Expected return on plan assets	0	0	0	0
Amortization of net loss	47	31	94	62
Net periodic benefit cost (income) loss	$ 81	$ 89	$ 162	$ 176