Goodwill and Other Identifiable Intangible Assets - Changes in Carrying Amount of Goodwill by Segment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)
Goodwill
Number of reporting units | item	6
Changes in the carrying amount of goodwill
Balance as of beginning of year	$ 25,777	$ 26,197
Acquisition	42,844
Foreign currency translation	(2,305)	(420)
Balance as of end of period	$ 66,316	25,777
Activated Carbon and Service
Goodwill
Number of reporting units | item	2
Changes in the carrying amount of goodwill
Balance as of beginning of year	$ 19,604	19,753
Foreign currency translation	(551)	(149)
Balance as of end of period	19,053	19,604
Equipment
Changes in the carrying amount of goodwill
Balance as of beginning of year	6,113	6,384
Foreign currency translation	47	(271)
Balance as of end of period	6,160	6,113
Consumer
Changes in the carrying amount of goodwill
Balance as of beginning of year	60	60
Balance as of end of period	60	$ 60
Other
Changes in the carrying amount of goodwill
Acquisition	42,844
Foreign currency translation	(1,801)
Balance as of end of period	$ 41,043