Assets Held for Sale and Discontinued Operations (Results of Operations Associated with Discontinued Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss) income from discontinued operations	$ 208	$ (4,862)
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	44	4,073
Other costs and expenses (benefits)	(164)	8,935
(Loss) income before taxes	208	(4,862)
Income tax expense	0	0
(Loss) income from discontinued operations	$ 208	$ (4,862)