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Basis of Presentation (Details) - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Change in Accounting Estimate [Line Items]    
Asset retirement obligation, current $ 14,820 $ 25,393
Asset retirement obligations, noncurrent 46,176 $ 34,671
Service Life    
Change in Accounting Estimate [Line Items]    
Asset retirement obligation, current (9,700)  
Asset retirement obligations, noncurrent $ 9,700