Discontinued Operations and Assets Held for Sale (Results of Operations Associated with Discontinued Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss) income from discontinued operations	$ (778)	$ 953,368	$ (6,907)	$ 1,027,632
Discontinued Operation | Malaysian Exploration And Production Operations And U.K., U.S. Refining And Marketing Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	0	972,737	4,074	1,328,110
Lease operating expenses	0	6,262	0	127,138
Depreciation, depletion and amortization	0	(1)	0	33,697
Other costs and expenses	778	11,079	10,981	81,560
(Loss) income before taxes	(778)	955,397	(6,907)	1,085,715
Income tax expense	0	2,029	0	58,083
(Loss) income from discontinued operations	$ (778)	$ 953,368	$ (6,907)	$ 1,027,632