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Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 2,136	$ 2,274	$ 5,192	$ 4,064
Rental income	15,613	15,131	30,954	31,231
Total revenue	17,749	17,405	36,146	35,295
Compressors - sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	1,360	1,891	2,212
Flares - sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	29	160	75	240
Other (parts/rebuilds) - sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,544	488	2,318	1,006
Service and maintenance
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	563	266	908	606
Total revenue	$ 563	$ 266	$ 908	$ 606

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