Discontinued Operations and Assets Held for Sale (Results of Operations Associated with Discontinued Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss) income from discontinued operations	$ (1,267)	$ 24,418	$ (6,129)	$ 74,264
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	1	159,961	4,074	355,373
Lease operating expenses	0	58,160	0	120,876
Depreciation, depletion and amortization	0	2,345	0	33,698
Other costs and expenses (benefits)	1,268	57,401	10,203	70,481
(Loss) income before taxes	(1,267)	42,055	(6,129)	130,318
Income tax expense	0	17,637	0	56,054
(Loss) income from discontinued operations	$ (1,267)	$ 24,418	$ (6,129)	$ 74,264