Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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	13,940	15,649
Expected return on plan assets	(11,168)	(9,477)	(22,336)	(18,954)
Amortization of net loss	941	3,882	1,882	7,764
Net periodic benefit (income) loss	(3,257)	2,230	(6,514)	4,459
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	35	27	69	54
Interest cost	23	37	45	74
Expected return on plan assets	0	0	0	0
Amortization of net loss	31	43	62	86
Net periodic benefit (income) loss	$ 89	$ 107	$ 176	$ 214