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Supplemental Information on Oil and Natural Gas Producing Activities (Unaudited) - Estimate of Changes in Standardized Measure of Discounted Future Net Cash Flows from Proved Reserves (Unaudited) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Roll Forward]      
Beginning present value $ 1,045,603 $ 749,294 $ 438,364
Changes during the year      
Revenues less production (155,772) (236,553) (239,838)
Net changes in prices, production and other costs (491,035) 316,095 347,458
Development costs incurred 90,591 80,050 35,517
Net changes in future development costs 450,162 (11,483) (64,484)
Extensions and discoveries 11,921 102,961 112,556
Revisions of previous quantity estimates (478,238) (91,038) 26,697
Accretion of discount 101,778 70,576 37,226
Net change in income taxes 0 56 23
Purchases of reserves in-place 0 35,713 454
Sales of reserves in-place (3,331) (2,029) (2,977)
Timing differences and other (207,389) 31,961 58,298
Net change for the year (681,313) 296,309 310,930
Ending present value $ 364,290 $ 1,045,603 $ 749,294