Property, Plant and Equipment (Aging of Capitalized Exploratory Well Costs) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) project well	Mar. 31, 2021 USD ($) project well	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 172,706	$ 182,401	$ 179,481	$ 181,616
No. of Wells (in wells) | well	13	11
No. of Projects (in projects) | project	7	5
Zero to one year
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 2,810	$ 0
No. of Wells (in wells) | well	2	0
No. of Projects (in projects) | project	2	0
One to two years
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 0	$ 23,514
No. of Wells (in wells) | well	0	3
No. of Projects (in projects) | project	0	3
Two to three years
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 23,667	$ 30,562
No. of Wells (in wells) | well	3	2
No. of Projects (in projects) | project	3	2
Three years or more
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 146,229	$ 128,325
No. of Wells (in wells) | well	8	6
No. of Projects (in projects) | project	2	0