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Asset Retirement Obligations (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2020
USD ($)
Asset Retirement Obligation Disclosure [Abstract]  
Asset retirement obligation liabilities expected, present value $ 26,900
Financial assurance in form of surety bond 28,200
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]  
Asset retirement obligations, beginning balance 12,883
Accretion expense 360
Asset retirement obligations, ending balance $ 13,243