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Field Equipment, Net - Additional Information (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Field Equipment [Line Items]      
Depreciation expense $ 2,080 $ 1,967 $ 1,968
Field equipment      
Field Equipment [Line Items]      
Depreciation expense 4,631 5,553 4,483
Field Equipment Under Operating Leases      
Field Equipment [Line Items]      
Write downs $ 326 $ 350 $ 195