Accumulated Other Comprehensive Income (Reclassifications) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenue	$ 860,779	$ 865,240	$ 1,729,181	$ 1,761,823
Interest expense, net	(28,019)	(30,775)	(55,621)	(62,789)
Income from continuing operations before taxes	34,377	58,286	41,249	128,564
Income tax benefit (provision)	(4,099)	(7,899)	(12,400)	(26,694)
Net income	23,697	51,595	21,038	111,565
Pension and Postretirement Benefit Plans	(278,545)	(289,427)	(579,527)	(592,237)
Reclassification out of Accumulated Other Comprehensive Loss | Cash flow hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenue	(36)	79	75	76
Cost of sales	29	(1)	45	(85)
Interest expense, net	0	(507)	0	(1,014)
Income from continuing operations before taxes	(7)	(429)	120	(1,023)
Income tax benefit (provision)	1	110	(31)	261
Net income	(6)	(319)	89	(762)
Reclassification out of Accumulated Other Comprehensive Loss | Available for sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net	(81)	214	(104)	190
Income tax benefit (provision)	21	(54)	27	(48)
Net income	(60)	160	(77)	142
Reclassification out of Accumulated Other Comprehensive Loss | Pension and postretirement benefit plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations before taxes	(9,435)	(10,432)	(18,720)	(21,408)
Income tax benefit (provision)	2,124	2,564	4,773	5,368
Net income	(7,311)	(7,868)	(13,947)	(16,040)
Reclassification out of Accumulated Other Comprehensive Loss | Transition credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pension and Postretirement Benefit Plans	1	2	3	3
Reclassification out of Accumulated Other Comprehensive Loss | Prior service costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pension and Postretirement Benefit Plans	(126)	(55)	(254)	(109)
Reclassification out of Accumulated Other Comprehensive Loss | Settlements
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pension and Postretirement Benefit Plans	(1,198)	0	(1,198)	0
Reclassification out of Accumulated Other Comprehensive Loss | Actuarial losses
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pension and Postretirement Benefit Plans	$ (8,112)	$ (10,379)	$ (17,271)	$ (21,302)