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Supplemental Information On Oil And Gas Exploration And Production Activities (Unaudited) - Changes In Standardized Measure Of Discontinued Future Net Cash Flows Relating To Proved Oil And Natural Gas Reserves (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Extractive Industries [Abstract]    
Standardized measure, beginning of year $ 789,577 $ 959,452
Sales of oil and gas produced, net of production costs (105,555) (150,708)
Sales of minerals in place 14 (458)
Net changes in prices and production costs (381,769) (565,240)
Extensions, discoveries, and improved recoveries 14,644 127,182
Changes in income taxes, net 17,826 12,697
Previously estimated development costs incurred during the period 66,788 210,520
Net changes in future development costs 258,741 118,348
Revisions of previous quantity estimates (273,781) (35,588)
Accretion of discount 81,999 107,432
Changes in timing of estimated cash flows and other (7,631) 5,940
Standardized measure, end of year 460,853 789,577
Standardized measure of discounted future net cash flows attributable to noncontrolling interests $ 246,900 $ 430,400