Business Segment, Geographic and Major Customer Information - Assets by Reportable Segments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 249,357	$ 285,883
Operating Segments | Energy Chemistry Technologies
Segment Reporting Information [Line Items]
Total assets	123,309	139,205
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	126,048	28,208
Total segments
Segment Reporting Information [Line Items]
Total assets	249,357	167,413
Held for sale
Segment Reporting Information [Line Items]
Total assets	$ 0	$ 118,470