Pensions and Other Postretirement Plans (Total Benefit/Cost) (Details 5) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Total Cost (Benefit) for the Year		$ 20,422	$ 18,221	$ 18,687
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)		(231,104)	101,013	(179,674)
Current year prior service cost		5,725	(4,262)	75
Amortization of prior service credit (cost)		4,142	947	(477)
Recognized net actuarial gain (loss)		2,046	11,349	6,527
Curtailments and settlements		91,676	30,267	0
Total Recognized in Other Comprehensive Income (Before Tax Effects)		(127,515)	139,314	(173,549)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		20,422	18,221	18,687
Interest cost		46,821	46,787	47,925
Expected return on assets		(122,790)	(129,220)	(121,411)
Amortization of prior service cost (credit)		2,882	150	170
Recognized actuarial loss (gain)		0	(9,969)	(4,410)
Net Periodic Cost (Benefit) for the Year		(52,665)	(74,031)	(59,039)
Curtailment		0	(806)	0
Settlement	$ (26,900)	(91,676)	(26,917)	0
Early retirement programs and special separation benefit expense		6,432	0	1,825
Total Cost (Benefit) for the Year		(137,909)	(101,754)	(57,214)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)		(245,402)	111,084	(180,885)
Current year prior service cost		5,725	7,183	75
Amortization of prior service credit (cost)		(2,882)	(150)	(170)
Recognized net actuarial gain (loss)		0	9,969	4,410
Curtailments and settlements		91,676	26,887	0
Total Recognized in Other Comprehensive Income (Before Tax Effects)		(150,883)	154,973	(176,570)
Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects)		(288,792)	53,219	(233,784)
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		858	819	858
Interest cost		4,314	3,865	4,233
Amortization of prior service cost (credit)		339	311	455
Recognized actuarial loss (gain)		2,314	2,403	1,774
Total Cost (Benefit) for the Year		7,825	7,398	7,320
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)		15,544	(7,552)	4,041
Current year prior service cost		0	1,028	0
Amortization of prior service credit (cost)		(339)	(311)	(455)
Recognized net actuarial gain (loss)		(2,314)	(2,403)	(1,774)
Total Recognized in Other Comprehensive Income (Before Tax Effects)		12,891	(9,238)	1,812
Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects)		20,716	(1,840)	9,132
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		0	892	1,028
Interest cost		289	620	779
Amortization of prior service cost (credit)		(7,363)	(1,408)	(148)
Recognized actuarial loss (gain)		(4,360)	(3,783)	(3,891)
Net Periodic Cost (Benefit) for the Year		(11,434)	(3,679)	(2,232)
Curtailment		0	(3,380)	0
Total Cost (Benefit) for the Year		(11,434)	(7,059)	(2,232)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)		(1,246)	(2,519)	(2,830)
Current year prior service cost		0	(12,473)	0
Amortization of prior service credit (cost)		7,363	1,408	148
Recognized net actuarial gain (loss)		4,360	3,783	3,891
Curtailments and settlements		0	3,380	0
Total Recognized in Other Comprehensive Income (Before Tax Effects)		10,477	(6,421)	1,209
Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects)		$ (957)	$ (13,480)	$ (1,023)