Pension and Other Post-Retirement Benefit Plans (Funded Status) (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]
Change in benefit obligation [Roll Forward]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	6,970	7,825	20,910	23,474
Change in plan assets [Roll Forward]
Employer contributions			8,200
Post-Retirement Healthcare Plans [Member]
Change in benefit obligation [Roll Forward]
Service cost	35	27	104	81
Interest cost	$ 23	$ 37	$ 68	$ 111