Pension and Other Postretirement Benefits - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pension Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	$ 289	$ 1,227	$ 921	$ 3,565
Interest Cost	1,078	1,527	3,262	4,782
Expected Return on Plan Assets	(2,075)	(3,526)	(6,250)	(7,246)
Settlement Loss	0	0	0	22,667
Actuarial Loss Amortization	737	626	2,449	2,288
Prior service cost amortization	3	(42)	8	(123)
Net Periodic Benefit Cost	32	(188)	390	25,933
Postretirement Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	(2)	2	1	5
Interest Cost	(1)	25	20	77
Expected Return on Plan Assets	0	0	0	0
Settlement Loss	0	0	0	0
Actuarial Loss Amortization	(85)	15	(85)	46
Prior service cost amortization	0	0	0	0
Net Periodic Benefit Cost	$ (88)	$ 42	$ (64)	$ 128