Business Segment, Geographic and Major Customer Information (Assets by Reportable Segments) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Assets	$ 285,883	$ 329,888
Held for sale	118,470	121,218
Operating Segments
Segment Reporting Information [Line Items]
Assets	167,413	208,670
Operating Segments \| Energy Chemistry Technologies
Segment Reporting Information [Line Items]
Assets	139,205	172,799
Corporate and Other
Segment Reporting Information [Line Items]
Assets	$ 28,208	$ 35,871

Amount classified as assets attributable to disposal group held for sale or disposed of.

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