Summary of Significant Accounting Policies - Impairments (Details) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2020 USD ($) item	Mar. 31, 2020 USD ($) item	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) item	Jun. 30, 2019 USD ($)
Intangible assets by major classification
Inventory write-down	$ 0		$ 0	$ 2,600	$ 0
Goodwill impairment	$ 0
Impairment of long-lived assets			0		0
Measurement Input, Discount Rate | Minimum
Intangible assets by major classification
Asset measurement input | item	10.35	10.35		10.35
Measurement Input, Discount Rate | Maximum
Intangible assets by major classification
Asset measurement input | item	13.00	13.00		13.00
Property, Plant and Equipment
Intangible assets by major classification
Impairment of long-lived assets	$ 0	$ 37,775	$ 0		$ 0
ROU asset
Intangible assets by major classification
Impairment of long-lived assets		2,845
Accounts receivable
Intangible assets by major classification
Impairment of long-lived assets		410
Railtronix LLC
Intangible assets by major classification
Goodwill impairment		$ 4,231
Loadcraft Industries Ltd
Intangible assets by major classification
Estimate change needed (as a percent)		40.00%