Segment Information - Expenditures for Long-Lived Assets and Total Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Information
Expenditures for long-lived assets	$ 33,794	$ 62,228	$ 63,912
Assets	775,218	656,518	621,661
Accounts payable and accrued liabilities
Segment Information
Property, plant and equipment expenditures	4,000	2,100	2,200
Activated Carbon and Service
Segment Information
Expenditures for long-lived assets	30,641	57,559	60,470
Assets	538,533	597,274	564,734
Equipment
Segment Information
Expenditures for long-lived assets	2,317	4,266	2,947
Assets	45,251	52,894	50,610
Consumer
Segment Information
Expenditures for long-lived assets	156	403	495
Assets	5,144	$ 6,350	$ 6,317
Other
Segment Information
Expenditures for long-lived assets	680
Assets	$ 186,290