Accumulated Other Comprehensive Income (Loss) (Reclassifications out of AOCI) (Details 3) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other income, net	$ 3,704	$ (5,556)	$ (1,228)	$ (29,351)	$ 12,559	$ (3,142)	$ (2,333)	$ (9,187)	$ (32,431)	$ (2,103)	$ (4,241)
Interest expense	7,192	6,776	8,386	7,425	6,531	6,135	17,165	8,071	29,779	37,902	33,886
Provision for (Benefit from) Income Taxes	39,100	15,200	16,700	27,600	12,400	10,000	16,100	13,600	98,600	52,100	(119,700)
Net of Tax	$ (146,017)	$ (42,965)	$ (57,195)	$ (81,702)	$ (56,738)	$ (125,070)	$ (46,635)	$ (42,965)	(327,879)	(271,408)	(302,489)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net of Tax									(69,526)	(31,203)	(3,370)
Foreign Currency Translation Adjustments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax									2,011		137
Provision for (benefit from) income taxes									0		0
Reclassifications, net of tax									2,011	0	137
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									2,011	0	137
Unrealized Gains (Losses) on Available- for- Sale Securities [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax									0	0
Pension and Other Postretirement Plans [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax									(97,864)	(42,563)	(6,050)
Provision for (benefit from) income taxes									26,422	11,492	2,421
Reclassifications, net of tax									(71,442)	(31,071)	(3,629)
Net Actuarial Loss [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax									(2,046)	(11,349)	(6,527)	[1]
Provision for (benefit from) income taxes									552	3,064	2,612
Reclassifications, net of tax									(1,494)	(8,285)	(3,915)
Net Prior Service Cost [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax									(4,142)	(947)	477	[1]
Provision for (benefit from) income taxes									1,118	256	(191)
Reclassifications, net of tax									(3,024)	(691)	286
Curtailment (Gains) Losses Included in Net Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, before tax									(91,676)	(30,267)	0	[1]
Provision for (benefit from) 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									(95)
Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense									(146)
Provision for (Benefit from) Income Taxes									51
Net of Tax									$ (95)
Cash Flow Hedges
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax										(132)
Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense										(163)	152
Provision for (Benefit from) Income Taxes										31	(30)
Net of Tax										$ (132)	$ 122

[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.