Segment Information - Results of Operations (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Jan. 01, 2017 segment	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) segment	Jun. 30, 2016 USD ($)
Segment Information
Number of reportable segments | segment	3			3
Net Sales		$ 152,998	$ 132,597	$ 295,701	$ 252,796
Income (loss) from operations		11,021	12,171	16,919	20,634
Interest income		26	29	32	35
Interest expense		(2,021)	(228)	(3,535)	(561)
Other income (expense) — net		5	(20)	505	203
Income before income tax provision		9,031	11,952	13,921	20,311
Depreciation and amortization		12,000	9,461	23,788	18,236
Activated Carbon
Segment Information
Net Sales		135,677	123,515	261,908	233,498
Income (loss) from operations		11,509	12,526	20,030	21,220
Depreciation and amortization		10,388	8,941	20,568	17,236
Alternative Materials
Segment Information
Net Sales		12,930	2,644	25,778	5,129
Income (loss) from operations		567	395	(237)	822
Depreciation and amortization		1,356	163	2,625	303
Advanced Water Purification
Segment Information
Net Sales		4,391	6,438	8,015	14,169
Income (loss) from operations		(1,055)	(750)	(2,874)	(1,408)
Depreciation and amortization		$ 256	$ 357	$ 595	$ 697