Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Total Assets	$ 9,668,660		$ 9,766,697
External Revenues	796,412	$ 841,716
Income (Loss)	114,658	214,314
Continuing operations
Segment Reporting Information [Line Items]
Total Assets	9,668,000
External Revenues	796,400	841,700
Income (Loss)	115,600	214,000
Discontinued operations, net of tax
Segment Reporting Information [Line Items]
Total Assets	700
External Revenues	0	0
Income (Loss)	(900)	300
Corporate
Segment Reporting Information [Line Items]
Total Assets	368,000
External Revenues	0	0
Income (Loss)	(27,600)	(28,700)
Exploration and Production | Operating Segments
Segment Reporting Information [Line Items]
Total Assets	9,300,000
External Revenues	796,400	841,700
Income (Loss)	143,100	242,700
Exploration and Production | Operating Segments | United States
Segment Reporting Information [Line Items]
Total Assets	7,030,700
External Revenues	659,600	682,300
Income (Loss)	134,500	226,000
Exploration and Production | Operating Segments | Canada
Segment Reporting Information [Line Items]
Total Assets	2,059,100
External Revenues	136,900	155,800
Income (Loss)	19,400	21,900
Exploration and Production | Operating Segments | Other
Segment Reporting Information [Line Items]
Total Assets	210,200
External Revenues	(100)	3,600
Income (Loss)	$ (10,800)	$ (5,200)