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Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Revenue from External Customer [Line Items] |  |  |  |  |
Revenue | $ 18,245 | $ 15,765 | $ 54,391 | $ 51,060 |
Revenue related to unsatisfied performance obligations | 0 |  | 0 |  |
Uncertain tax position | $ 0 |  | 0 |  |
Sales |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |
Revenue recognized |  |  | 1,100 |  | $ 533
Rental income |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |
Revenue recognized |  |  | 2 |  | $ 73
Bill and Hold Arrangement |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |
Revenue |  |  | $ 0 | $ 852 |
Minimum |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |
Amortization period of capitalized contract costs | 1 year |  | 1 year |  |
Rental Contracts, Excluding Large Horsepower Compressors | Minimum |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |
Rental contract term | 6 months |  | 6 months |  |
Rental Contracts, Excluding Large Horsepower Compressors | Maximum |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |
Rental contract term | 24 months |  | 24 months |  |
Rental Contracts, Large Horsepower Compressors | Maximum |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |
Rental contract term | 60 months |  | 60 months |  |

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