Pension and Postretirement Plans (Consolidated Balance Sheet) (Details 2) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	$ 1,003,558	$ 1,056,777
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	1,003,558	1,056,777
Current liability	0	0
Noncurrent liability	0	0
Recognized asset (liability)	1,003,558	1,056,777
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	0	0
Current liability	(6,321)	(5,838)
Noncurrent liability	(96,227)	(104,244)
Recognized asset (liability)	(102,548)	(110,082)
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liability	(1,399)	(1,920)
Noncurrent liability	(7,124)	(20,865)
Recognized asset (liability)	$ (8,523)	$ (22,785)

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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