XML 51 R40.htm IDEA: XBRL DOCUMENT v3.20.2
Property, Plant and Equipment - Schedule of Asset Retirement Obligations (Parenthetical) (Details)
$ in Millions
6 Months Ended
Jun. 30, 2020
USD ($)
ILX and Castex  
Property, Plant and Equipment [Line Items]  
Fair value of asset retirement obligations assumed $ 41.2