Segment Information - Reconciliation to Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Income from continuing operations, net of income taxes	$ 128.8	$ 384.4	$ 617.0	$ 675.9
Depreciation, depletion and amortization	82.3	80.7	239.2	227.4
Asset retirement obligation expenses	15.4	13.1	46.3	40.8
Restructuring charges	0.9	1.0	3.0	2.8
Asset impairment	0.0	1.7	2.0	1.7
Provision for NARM and Shoal Creek loss	3.3	0.0	37.0	0.0
Changes in amortization of basis difference related to equity affiliates	(0.5)	(0.5)	(1.2)	(1.7)
Interest expense	13.8	33.8	45.5	110.8
Net loss on early debt extinguishment	0.0	8.7	8.8	34.5
Interest income	(20.3)	(4.9)	(56.5)	(6.3)
Unrealized (gains) losses on derivative contracts related to forecasted sales	0.0	(90.4)	(159.0)	235.1
Unrealized losses (gains) on foreign currency option contracts	0.5	1.4	(0.1)	4.4
Take-or-pay contract-based intangible recognition	(0.7)	(0.8)	(1.9)	(2.2)
Income tax provision	46.5	10.7	238.7	21.0
Adjusted EBITDA	$ 270.0	$ 438.9	$ 1,018.8	$ 1,344.2