Accumulated Other Comprehensive Income (Loss) (Reclassifications out of AOCI) (Details 3) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other income, net		$ (203,524)	$ (222)	$ (8,100)	$ (2,688)	$ 3,704	$ (5,556)	$ (1,228)	$ (29,351)	$ (214,534)	$ (32,431)	$ (2,103)
Interest expense		16,008	7,247	7,377	7,678	7,192	6,776	8,386	7,425	38,310	29,779	37,902
Provision for Income Taxes		80,800	30,000	41,900	(45,400)	39,100	15,200	16,700	27,600	107,300	98,600	52,100
Net of Tax		$ (236,943)	$ (78,054)	$ (18,862)	$ 33,891	$ (146,017)	$ (42,965)	$ (57,195)	$ (81,702)	(299,968)	(327,879)	(271,408)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net of Tax										3,333	(69,526)	(31,203)
Foreign Currency Translation Adjustments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax											2,011
Provision for income taxes											0
Reclassifications, net of tax										0	2,011
Foreign Currency Translation Adjustments [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other income, net										0	2,011	0
Pension and Other Postretirement Plans [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax										3,899	(97,864)	(42,563)
Provision for income taxes										(1,053)	26,422	11,492
Reclassifications, net of tax										2,846	(71,442)	(31,071)
Net Actuarial Loss [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax	[1]									1,219	(2,046)	(11,349)
Provision for income taxes										(329)	552	3,064
Reclassifications, net of tax										890	(1,494)	(8,285)
Net Prior Service Cost [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax	[1]									2,680	(4,142)	(947)
Provision for income taxes										(724)	1,118	256
Reclassifications, net of tax										1,956	(3,024)	(691)
Curtailment (Gains) Losses Included in Net Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax	[1]									0	(91,676)	(30,267)
Provision for income taxes											24,752	8,172
Reclassifications, net of tax											(66,924)	(22,095)
Cash Flow Hedges
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax										487	(95)
Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense										474	(146)
Provision for Income Taxes										13	51
Net of Tax										$ 487	$ (95)
Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense												(163)
Provision for Income Taxes												31
Net of Tax												$ (132)

[1] These accumulated other comprehensive income components are included in the computation of net periodic pension and postretirement plan cost (see Note 15) and are included in non-operating pension and postretirement benefit income in the Company’s Consolidated Statements of Operations.