Property, Plant and Equipment (Narrative) (Details) - USD ($)	1 Months Ended		3 Months Ended			9 Months Ended
	Aug. 31, 2022	Jun. 30, 2022	Sep. 30, 2022	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Well costs			$ 181,461,000	$ 186,623,000		$ 181,461,000	$ 186,623,000	$ 179,481,000	$ 181,616,000
Exploratory well costs capitalized more than one year			172,600,000			172,600,000
Impairment of oil and gas properties					$ 171,300,000	0
Impairment of assets			$ 0	$ 0		0	$ 171,296,000
Proceeds from sale of oil and gas property and equipment					$ 267,700,000
Discontinued Operations, Disposed of by Sale | Thunderhawk Field
Property, Plant and Equipment [Line Items]
Percentage of ownership sold			62.50%
Cash received from divestiture			$ 20,000,000			20,000,000
Closing adjustment			22,200,000			22,200,000
Net payment			2,200,000
Gain on sale			18,800,000
Discontinued Operations, Disposed of by Sale | Thunderhawk Field | Buyer
Property, Plant and Equipment [Line Items]
Impairment of assets			47,900,000
Discontinued Operations, Disposed of by Sale | CA-2 Asset
Property, Plant and Equipment [Line Items]
Gain on sale			0
Contingent consideration value			8,700,000			8,700,000
Kodak field
Property, Plant and Equipment [Line Items]
Percentage of field acquired		11.00%
Consideration transferred		$ 48,500,000
Lucius field
Property, Plant and Equipment [Line Items]
Percentage of field acquired	3.37%			3.50%			3.50%
Consideration transferred	$ 77,100,000			$ 22,500,000
Terra Nova
Property, Plant and Equipment [Line Items]
Additional percentage acquired through commercial settlement								7.525%
Vietnam
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year			95,500,000			95,500,000
United States
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year			54,900,000			54,900,000
MEXICO
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year			15,500,000			15,500,000
Brunei
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year			2,800,000			2,800,000
Canada
Property, Plant and Equipment [Line Items]
Exploratory well costs capitalized more than one year			$ 3,900,000			$ 3,900,000