Business Segment, Geographic and Major Customer Information - Assets by Reportable Segments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 263,816	$ 285,883
Operating Segments | Energy Chemistry Technologies
Segment Reporting Information [Line Items]
Total assets	144,106	139,205
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	119,710	28,208
Total segments
Segment Reporting Information [Line Items]
Total assets	263,816	167,413
Held for sale
Segment Reporting Information [Line Items]
Total assets	$ 0	$ 118,470