Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Goodwill and Other Intangibles (Details)	3 Months Ended		9 Months Ended
Goodwill and Other Intangibles (Details)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) reporting_unit	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Goodwill [Line Items]
Number of reporting units \| reporting_unit			2
Goodwill	$ 2,116,000		$ 2,116,000		$ 2,116,000
Goodwill impairments			0	$ 0
Intangible assets abandonment	76,000	$ 0	127,000	317,000
Air Pollution Control Segment
Goodwill [Line Items]
Goodwill	0		$ 0
Intangible assets abandonment	0			0
FUEL CHEM Segment
Goodwill [Line Items]
Goodwill					$ 2,116,000
Intangible assets abandonment	$ 0			$ 0