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Supplemental Disclosures to the Balance Sheets and Statements of Cash Flows - Schedule of Other Current Assets (Details) - USD ($)
$ in Thousands
Dec. 31, 2019
Dec. 31, 2018
Feb. 28, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]      
Prepaid expenses $ 4,577 $ 4,656  
Materials and supplies 10,544 5,461  
Oil inventories 3,432 3,786  
Other 846 464  
Other current assets $ 19,399 $ 14,367 $ 16,752