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Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)
Revenue from External Customer [Line Items]
Cash equivalents, qualification, maximum original maturity of short-term investments	3 months
Customer deposit requirements, large custom contracts, maximum percentage	50.00%
Allowance for doubtful accounts	$ 1,161,000	$ 918,000
Revenues	68,055,000	78,444,000
Revenue recognized	$ 73,000	48,000
Amortization period of capitalized contract costs	1 year
Impairment of goodwill	$ 0	10,039,000
Product warranty reserves	0	74,000
Uncertain tax positions	$ 0
Number of business segments | segment	1
Minimum
Revenue from External Customer [Line Items]
Rental contract term	6 months
Property and equipment, estimated useful life	3 years
Minimum | Rental Equipment
Revenue from External Customer [Line Items]
Property and equipment, estimated useful life	15 years
Maximum
Revenue from External Customer [Line Items]
Rental contract term	60 months
Property and equipment, estimated useful life	39 years
Maximum | Rental Equipment
Revenue from External Customer [Line Items]
Property and equipment, estimated useful life	25 years
Developed Technology
Revenue from External Customer [Line Items]
Intangible assets, useful life	20 years
Intangible assets, weighted average remaining life	5 years
Bill and Hold Arrangement
Revenue from External Customer [Line Items]
Revenues	$ 900,000	$ 11,600,000
Rental Contracts, Excluding Large Horsepower Compressors | Minimum
Revenue from External Customer [Line Items]
Rental contract term	6 months
Rental Contracts, Excluding Large Horsepower Compressors | Maximum
Revenue from External Customer [Line Items]
Rental contract term	24 months
Rental Contracts, Large Horsepower Compressors | Maximum
Revenue from External Customer [Line Items]
Rental contract term	60 months
Customer Concentration Risk | One Customer | Accounts Receivable
Revenue from External Customer [Line Items]
Concentration risk, percentage	35.00%	35.00%
Customer Concentration Risk | Oxy | Sales and Rental Income
Revenue from External Customer [Line Items]
Concentration risk, percentage	30.00%	36.00%

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