Business Segment, Geographic and Major Customer Information (Assets by Reportable Segments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Assets	$ 329,888	$ 383,215
Held for sale	0	43,900
Operating Segments
Segment Reporting Information [Line Items]
Assets	329,888	339,315
Operating Segments | Energy Chemistry Technologies
Segment Reporting Information [Line Items]
Assets	177,797	184,328
Operating Segments | Consumer and Industrial Chemistry Technologies
Segment Reporting Information [Line Items]
Assets	116,600	98,105
Corporate and Other
Segment Reporting Information [Line Items]
Assets	$ 35,491	$ 56,882