Exploratory Well Costs (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2020 USD ($) well	Dec. 31, 2019 USD ($) well	Dec. 31, 2018 USD ($) well
Capitalized Exploratory Well Costs [Abstract]
Balance at January 1		$ 25,897	$ 4,121	$ 2,167
Additions Pending the Determination of Proved Reserves		107,852	83,175	10,304
Reclassifications to Proved Properties		(81,071)	(39,325)	(7,917)
Costs Charged to Expense (1)	[1]	(23,822)	(22,074)	(433)
Balance at December 31		$ 28,856	$ 25,897	$ 4,121
Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects | well		1	0	0
Capitalized Exploratory Well Costs that Have Been Capitalized for Period of One Year or Less		$ 26,408	$ 25,897	$ 4,121
Capitalized Exploratory Well Costs that Have Been Capitalized for Period Greater than One Year		$ 2,448	$ 0	$ 0

[1] Includes capitalized exploratory well costs charged to either dry hole costs or impairments.