Goodwill and Other Intangibles - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill			$ 29,835	$ 29,835	$ 29,835
Accumulated impairment losses			11,600	11,600	11,600
Asset impairment charges			$ 2,234	1	2,234
Asset Purchase Agreement - Alternative Fuel Supply Technology
Finite-Lived Intangible Assets [Line Items]
Guaranteed payment	$ 1,200	$ 1,200		$ 400	1,000
Additional payment for future sales milestones	3,300
Asset Purchase Agreement - Alternative Fuel Supply Technology | Intellectual Property
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	1,500				$ 1,000	$ 500
Asset Purchase Agreement - Alternative Fuel Supply Technology | Developed technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 2,700
Useful life	3 years