Amortizable Intangible Assets - Goodwill and Intangible Assets, Net (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Amortizable Intangible assets
Gross Carrying Amount	$ 53,178				$ 54,537				$ 53,178	$ 54,537
Accumulated Amortization	(28,776)				(25,211)				(28,776)	(25,211)
Amortization of Intangible Assets									(6,200)	(6,000)	$ (6,100)
Intangible assets, net	24,402				29,326				24,402	29,326
Finite-lived Intangible Assets Acquired									879	800
Goodwill, Other Increase (Decrease)									(189)	(189)
Impairment of goodwill	6,686	$ 0	$ 0	$ 0	0	$ 0	$ 0	$ 0	6,686	0	0
Foreign exchange										16
Finite Lived Intangible Assets Removal of Fully Amortized Assets, Net									0	0
2019	5,319								5,319
2020	5,287								5,287
2021	4,807								4,807
2022	2,928								2,928
2023	2,124								2,124
Thereafter	3,321								3,321
Finite-Lived Intangible Assets, Net	23,786								23,786
Increase (Decrease) in Other Current Assets									5,297	(2,016)	(2,180)
Patents
Amortizable Intangible assets
Gross Carrying Amount	2,109				2,350				2,109	2,350	1,718
Accumulated Amortization	(411)				(545)				(411)	(545)	(528)
Amortization of Intangible Assets									(107)	(187)
Intangible assets, net	1,698				1,805				1,698	1,805	1,190
Foreign exchange										2
Finite Lived Intangible Assets Removal of Fully Amortized Assets, Gross									241	170
Accumulated amortization of removal of fully amortized asset									241	170
Finite Lived Intangible Assets Removal of Fully Amortized Assets, Net										0
Unpatented Technology
Amortizable Intangible assets
Gross Carrying Amount	20,662				21,667				20,662	21,667	21,162
Accumulated Amortization	(12,344)				(10,979)				(12,344)	(10,979)	(9,003)
Amortization of Intangible Assets									(2,557)	(1,976)
Intangible assets, net	8,318				10,688				8,318	10,688	12,159
Reclassifications									(277)
Foreign exchange									(90)	505
Finite Lived Intangible Assets Removal of Fully Amortized Assets, Gross									1,192
Accumulated amortization of removal of fully amortized asset									1,192
Finite Lived Intangible Assets Removal of Fully Amortized Assets, Net									0
Noncompete Agreements Trademarks and Other
Amortizable Intangible assets
Gross Carrying Amount	12,225				12,225				12,225	12,225	6,727
Accumulated Amortization	(3,719)				(2,817)				(3,719)	(2,817)	(4,100)
Amortization of Intangible Assets									(1,757)	(2,495)
Intangible assets, net	8,506				9,408				8,506	9,408	2,627
Finite-lived Intangible Assets Acquired									879	9,260
Reclassifications									24
Foreign exchange										16
Finite Lived Intangible Assets Removal of Fully Amortized Assets, Gross									(855)	(3,778)
Accumulated amortization of removal of fully amortized asset									855	3,778
Customer Relationships
Amortizable Intangible assets
Gross Carrying Amount	17,563				17,678				17,563	17,678	21,217
Accumulated Amortization	(12,299)				(10,869)				(12,299)	(10,869)	(14,945)
Amortization of Intangible Assets									(1,430)	(1,574)
Intangible assets, net	5,264				6,809				5,264	6,809	$ 6,272
Finite-lived Intangible Assets Acquired										1,091
Reclassifications										626
Foreign exchange									(115)	394
Finite Lived Intangible Assets Removal of Fully Amortized Assets, Gross										(5,650)
Accumulated amortization of removal of fully amortized asset										5,650
Finite Lived Intangible Assets Removal of Fully Amortized Assets, Net										0
North America
Amortizable Intangible assets
Gross Carrying Amount	30,825				30,775				30,825	30,775
Accumulated Amortization	(16,002)				(13,732)				(16,002)	(13,732)
Intangible assets, net	$ 14,823				$ 17,043				14,823	17,043
Goodwill, Other Increase (Decrease)									300	3
Impairment of goodwill									0
Europe | Customer Relationships
Amortizable Intangible assets
Reclassifications										$ (600)
Increase (Decrease) in Other Current Assets									$ 600
Maximum
Amortizable Intangible assets
Finite-Lived Intangible Asset, Useful Life									21 years
Minimum
Amortizable Intangible assets
Finite-Lived Intangible Asset, Useful Life									3 years