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Asset Retirement Obligations - Schedule of Changes in Asset Retirement Obligations (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2017
USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]  
Balance at December 31, 2016 $ 49,687
Liabilities incurred during period 351
Liabilities settled during period (89)
Accretion expense during period 655 [1]
Revisions to estimates (215)
Balance at March 31, 2017 $ 50,389
[1] Included in depreciation, depletion and amortization on the Company’s Condensed Consolidated Statement of Operations.