Business Combinations - Narratives (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	May 15, 2017	Mar. 11, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition
Net cash paid					$ 19,121	$ 73,063
Cost of goods sold			$ 68,705	$ 63,056	204,527	$ 190,528
Noliac A/S
Business Acquisition
Net cash paid	$ 19,300
Net cash paid	19,121
Cash acquired in acquisition	$ 199
CTG Advanced Materials, LLC
Business Acquisition
Net cash paid		$ 73,063
Cash acquired in acquisition		$ 4
Acquisition related cost					$ 804