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Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 2,050	$ 904	$ 7,242	$ 4,968
Rental income	16,195	14,861	47,149	46,092
Total revenue	18,245	15,765	54,391	51,060
Compressors - sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	1,891	2,211
Flares - sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	74	67	149	308
Other (parts/rebuilds) - sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,398	469	3,716	1,475
Service and maintenance
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 578	$ 368	$ 1,486	$ 974

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