Goodwill (Changes in the Carrying Value of Goodwill) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in the carrying value of goodwill:
Goodwill impairment recognized	$ 0	$ (37,180,000)	$ 0
Energy Chemistry Technologies
Changes in the carrying value of goodwill:
Goodwill, gross	37,180,000	37,180,000
Accumulated impairment losses	(37,180,000)	0
Goodwill, net	0	0	37,180,000
Goodwill impairment recognized	0	(37,180,000)
Acquisition goodwill recognized	0	0
Goodwill, gross	0	37,180,000	37,180,000
Accumulated impairment losses	0	(37,180,000)	0
Goodwill, net	$ 0	$ 0	$ 37,180,000