Pensions and Other Postretirement Plans (Consolidated Balance Sheet) (Details 2) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	$ 1,292,350	$ 1,003,558
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	1,292,350	1,003,558
Current liability	0	0
Noncurrent liability	0	0
Recognized asset (liability)	1,292,350	1,003,558
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	0	0
Current liability	(6,447)	(6,321)
Noncurrent liability	(109,746)	(96,227)
Recognized asset (liability)	(116,193)	(102,548)
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liability	(1,153)	(1,399)
Noncurrent liability	(5,663)	(7,124)
Recognized asset (liability)	$ (6,816)	$ (8,523)

Amount of asset (liability), recognized in statement of financial position, for defined benefit pension and other postretirement plans.

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Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.

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Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as noncurrent.

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