Accumulated Other Comprehensive Income (Loss) (Schedule of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017
Change in Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance		$ (114,405)
Cumulative-effect adjustment for the adoption of ASU 2017-12				$ 0
Ending balance		(116,708)
Foreign Currency Translation
Change in Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance		(23,240)	$ (16,183)
Cumulative-effect adjustment for the adoption of ASU 2017-12				0
Amounts recognized into AOCI		244	4,333
Currency impact		0	0
Amounts reclassified from AOCI, Currency		0	0
Tax effect		(270)	0
Other comprehensive income (loss), net of tax		(26)	4,333
Ending balance		(23,266)	(11,850)
Derivative Instruments
Change in Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance		(2,866)	351
Cumulative-effect adjustment for the adoption of ASU 2017-12				(275)
Amounts recognized into AOCI		(3,515)	1,464
Currency impact		0	0
Amounts reclassified from AOCI, Derivatives	[1]	(483)	341
Tax effect		944	(335)
Other comprehensive income (loss), net of tax		(3,054)	1,470
Ending balance		(5,920)	1,546
Pension and Other Post-retirement Benefits
Change in Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance		(88,299)	(89,340)
Cumulative-effect adjustment for the adoption of ASU 2017-12				0
Amounts recognized into AOCI		0	0
Currency impact		34	(484)
Amounts reclassified from AOCI, Pension/PRW	[2]	970	1,606
Tax effect		(227)	(367)
Other comprehensive income (loss), net of tax		777	755
Ending balance		(87,522)	(88,585)
Accumulated Other Comprehensive Loss
Change in Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance		(114,405)	(105,172)
Cumulative-effect adjustment for the adoption of ASU 2017-12				$ (275)
Amounts recognized into AOCI		(3,271)	5,797
Currency impact		34	(484)
Amounts reclassified from AOCI		487	1,947
Tax effect		447	(702)
Other comprehensive income (loss), net of tax		(2,303)	6,558
Ending balance		$ (116,708)	$ (98,889)

[1] We reclassified natural gas contracts through cost of sales and the interest rate swaps through interest expense on the Condensed Consolidated Statements of Operations. See note 8 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 Condensed Consolidated Statements of Operations. See note 6 for additional information.