Pension and Postretirement Plans (Total Benefit/Cost) (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Cost (Benefit)	$ 5,221	$ 4,940
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5,221	4,940
Interest cost	11,592	11,255
Expected return on assets	(30,838)	(32,486)
Amortization of prior service cost (credit)	409	42
Recognized actuarial loss (gain)	(37)	(1,046)
Net Periodic Cost (Benefit)	(13,653)	(17,295)
Curtailment gain	0	(806)
Net Periodic Cost (Benefit)	(13,653)	(18,101)
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	214	205
Interest cost	1,078	966
Amortization of prior service cost (credit)	85	78
Recognized actuarial loss (gain)	579	601
Net Periodic Cost (Benefit)	1,956	1,850
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	268
Interest cost	72	170
Amortization of prior service cost (credit)	(1,841)	(44)
Recognized actuarial loss (gain)	(1,090)	(922)
Net Periodic Cost (Benefit)	$ (2,859)	$ (528)