Accumulated Comprehensive Income (Loss) (Schedule of AOCI) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ (105,172)
Change in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Ending balance		(114,405)	$ (105,172)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(16,183)	(27,828)
Change in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amounts recognized into AOCI		(7,057)	12,835
Currency impact		0	0
Amounts reclassified from AOCI, Currency		0	0
Tax effect		0	(1,190)
Other comprehensive income (loss), net of tax		(7,057)	11,645
Ending balance		(23,240)	(16,183)
Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		351	(515)
Change in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amounts recognized into AOCI		(3,242)	(286)
Currency impact		0	0
Amounts reclassified from AOCI, Derivatives	[1]	(711)	1,780
Tax effect		1,011	(628)
Other comprehensive income (loss), net of tax		(2,942)	866
Ending balance		(2,866)	351
Pension and Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(89,340)	(96,854)
Change in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amounts recognized into AOCI		(5,245)	6,307
Currency impact		(164)	(152)
Amounts reclassified from AOCI, Pension/PRW	[2]	6,431	5,586
Tax effect		19	(4,227)
Other comprehensive income (loss), net of tax		1,041	7,514
Ending balance		(88,299)	(89,340)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(105,172)	(125,197)
Change in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amounts recognized into AOCI		(15,544)	18,856
Currency impact		(164)	(152)
Amounts reclassified from AOCI		5,720	7,366
Tax effect		1,030	(6,045)
Other comprehensive income (loss), net of tax		(8,958)	20,025
Ending balance		$ (114,405)	(105,172)
Accounting Standards Update 2017-12
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative-effect adjustment			0
Accounting Standards Update 2017-12 | Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative-effect adjustment			0
Accounting Standards Update 2017-12 | Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative-effect adjustment			(275)
Accounting Standards Update 2017-12 | Pension and Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative-effect adjustment			0
Accounting Standards Update 2017-12 | Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative-effect adjustment			$ (275)

[1] We reclassified natural gas contracts through cost of sales and the interest rate swaps through interest expense on the Consolidated Statements of Operations. See note 12 for additional information.

[2] We reclassified the net pension and non-pension post-retirement benefits amortization and settlement charges through other income (expense) on the Consolidated Statements of Operations. See notes 8 and 9 for additional information.