Segment Information - Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Nov. 02, 2016
Segment Information
Goodwill	$ 72,518	$ 66,316
Activated Carbon and Filter Aid Business (New Business)
Segment Information
Goodwill			$ 45,410
Activated Carbon
Segment Information
Goodwill	42,100
Activated Carbon | Activated Carbon and Filter Aid Business (New Business)
Segment Information
Goodwill	27,700
Goodwill adjustments
Acquisition post closing adjustments	1,500
Alternative Materials
Segment Information
Goodwill	18,400
Alternative Materials | Activated Carbon and Filter Aid Business (New Business)
Segment Information
Goodwill	17,700
Goodwill adjustments
Acquisition post closing adjustments	1,100
Advanced Water Purification
Segment Information
Goodwill	$ 12,000