Business Segment, Geographic and Major Customer Information - Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Summarized financial information regarding reportable segments
Net revenue from external customers	$ 70,989	$ 79,458	$ 190,591	$ 244,589
Income (loss) from operations	(3,222)	(3,103)	(56,508)	(4,977)
Depreciation and amortization	2,957	3,067	8,984	9,091
Capital expenditures	1,334	1,647	4,561	6,155
Operating Segments | Energy Chemistry Technologies
Summarized financial information regarding reportable segments
Net revenue from external customers	53,709	61,167	134,324	187,807
Income (loss) from operations	3,920	6,867	(34,175)	24,715
Depreciation and amortization	1,734	1,863	5,300	5,507
Capital expenditures	302	324	2,480	2,794
Operating Segments | Consumer and Industrial Chemistry Technologies
Summarized financial information regarding reportable segments
Net revenue from external customers	17,280	18,291	56,267	56,782
Income (loss) from operations	858	985	3,937	5,906
Depreciation and amortization	699	590	2,049	1,752
Capital expenditures	171	682	767	1,580
Corporate and Other
Summarized financial information regarding reportable segments
Net revenue from external customers	0	0	0	0
Income (loss) from operations	(8,000)	(10,955)	(26,270)	(35,598)
Depreciation and amortization	524	614	1,635	1,832
Capital expenditures	$ 861	$ 641	$ 1,314	$ 1,781