Pension and Postretirement Plans (Total Benefit/Cost) (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Cost (Benefit)	$ (13,784)	$ (13,653)
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5,783	5,221
Interest cost	8,169	11,592
Expected return on assets	(28,444)	(30,838)
Amortization of prior service cost (credit)	708	409
Recognized actuarial loss (gain)	0	(37)
Net Periodic Cost (Benefit)	(13,784)	(13,653)
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	238	214
Interest cost	919	1,078
Amortization of prior service cost (credit)	83	85
Recognized actuarial loss (gain)	1,317	579
Net Periodic Cost (Benefit)	2,557	1,956
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	62	72
Amortization of prior service cost (credit)	(120)	(1,841)
Recognized actuarial loss (gain)	(1,097)	(1,090)
Net Periodic Cost (Benefit)	$ (1,155)	$ (2,859)