UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Revenues	$ 983.6	$ 1,364.0
Costs and expenses
Operating costs and expenses (exclusive of items shown separately below)	814.2	846.6
Depreciation, depletion and amortization	79.8	76.3
Asset retirement obligation expenses	12.9	15.4
Selling and administrative expenses	22.0	22.8
Restructuring charges	0.1	0.1
Other operating (income) loss:
Net gain on disposals	(2.1)	(1.9)
Asset impairment	0.0	2.0
Provision for NARM loss	1.8	0.0
Loss (income) from equity affiliates	3.7	(1.8)
Operating profit	51.2	404.5
Interest expense	14.7	18.4
Net loss on early debt extinguishment	0.0	6.8
Interest income	(19.2)	(13.1)
Net periodic benefit credit, excluding service cost	(10.1)	(9.7)
Income from continuing operations before income taxes	65.8	402.1
Income tax provision	20.1	118.0
Income from continuing operations, net of income taxes	45.7	284.1
Loss from discontinued operations, net of income taxes	(0.7)	(1.3)
Net income	45.0	282.8
Less: Net income attributable to noncontrolling interests	5.4	14.3
Net income attributable to common stockholders	$ 39.6	$ 268.5
Income from continuing operations:
Basic income per share	$ 0.32	$ 1.87
Diluted income per share	0.30	1.69
Net income attributable to common stockholders:
Basic income per share	0.31	1.86
Diluted income per share	$ 0.29	$ 1.68