Pension and Postretirement Plans (Total Benefit/Cost) (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5,457	$ 5,142	$ 17,044	$ 15,326
Special separation benefit expense	7,783		13,797
Net Periodic Cost (Benefit)			(27,669)	(33,061)
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5,457	5,142	17,044	15,326
Interest cost	8,139	11,743	24,448	35,078
Expected return on assets	(28,347)	(30,832)	(85,081)	(91,955)
Amortization of prior service cost (credit)	708	824	2,123	2,058
Net Periodic Cost (Benefit)	(14,043)	(13,123)	(41,466)	(39,493)
Special separation benefit expense	7,783	(175)	13,797	6,432
Net Periodic Cost (Benefit)	(6,260)	(13,298)	(27,669)	(33,061)
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	238	214	715	643
Interest cost	920	1,079	2,759	3,236
Amortization of prior service cost (credit)	83	85	248	254
Recognized actuarial loss (gain)	1,316	579	3,950	1,736
Net Periodic Cost (Benefit)	2,557	1,957	7,672	5,869
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	41	72	125	216
Amortization of prior service cost (credit)	(120)	(1,841)	(361)	(5,522)
Recognized actuarial loss (gain)	(1,012)	(1,090)	(3,036)	(3,270)
Net Periodic Cost (Benefit)	$ (1,091)	$ (2,859)	$ (3,272)	$ (8,576)