Property, Plant and Equipment (Narrative) (Details) $ in Thousands	1 Months Ended	9 Months Ended
	Jul. 31, 2019 USD ($) business	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Well costs		$ 187,859	$ 217,326	$ 280,735	$ 207,855
Exploratory well costs capitalized more than one year		179,900
Impairment of oil and gas Properties		1,206,284
Malaysia Subsidiaries
Property, Plant and Equipment [Line Items]
Number of businesses divested (in businesses) | business	2
Cash received from divestiture	$ 2,000,000
Gain (loss) on disposition of business	960,000
Contingent bonus payment	$ 100,000
Vietnam
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year		88,200
United States
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year		46,000
Impairment of oil and gas Properties		1,152,515
Brunei
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year		25,300
MEXICO
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year		15,600
Canada
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year		$ 4,800