UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash Flows From Operating Activities
Net income (loss)	$ 282.8	$ (120.6)
Loss from discontinued operations, net of income taxes	1.3	0.8
Income (loss) from continuing operations, net of income taxes	284.1	(119.8)
Adjustments to reconcile income (loss) from continuing operations, net of income taxes to net cash provided by (used in) operating activities:
Asset impairment	2.0	0.0
Depreciation, depletion and amortization	76.3	72.9
Other Noncash Expense	1.6	3.8
Deferred income taxes	46.0	(6.4)
Noncash share-based compensation	1.7	2.0
Net gain on disposals	(1.9)	(4.9)
Other Noncash Income	(9.2)	0.0
Net loss on early debt extinguishment	6.8	23.5
Income from equity affiliates	(1.8)	(44.7)
Foreign currency option contracts	2.2	(3.3)
Changes in current assets and liabilities:
Accounts receivable	70.8	(6.9)
Inventories	(35.4)	(42.4)
Other current assets	43.5	(80.0)
Accounts payable and accrued expenses	(39.6)	(28.4)
Collateral arrangements	(45.9)	(28.7)
Asset retirement obligations	2.5	4.7
Workers’ compensation obligations	(0.9)	(0.6)
Postretirement benefit obligations	(14.4)	(15.9)
Pension obligations	0.4	(0.6)
Other, net	0.6	3.2
Net cash provided by (used in) continuing operations	389.4	(272.5)
Net cash used in discontinued operations	(3.1)	(1.2)
Net cash provided by (used in) operating activities	386.3	(273.7)
Cash Flows From Investing Activities
Additions to property, plant, equipment and mine development	(55.7)	(29.7)
Changes in accrued expenses related to capital expenditures	(1.6)	(7.0)
Proceeds from disposal of assets, net of receivables	2.9	3.6
Contributions to joint ventures	(206.2)	(126.6)
Distributions from joint ventures	202.0	148.2
Proceeds from Equity Method Investment, Distribution, Return of Capital	0.0	47.2
Other, net	(0.1)	0.5
Net cash (used in) provided by investing activities	(58.5)	35.2
Cash Flows From Financing Activities
Proceeds from long-term debt	0.0	545.0
Repayments of long-term debt	(2.7)	(599.9)
Payment of debt issuance and other deferred financing costs	(0.3)	(19.2)
Proceeds from Issuance of Common Stock	0.0	222.0
Repurchase of employee common stock relinquished for tax withholding	(13.2)	(2.0)
Distributions to noncontrolling interests	(22.8)	(13.8)
Other, net	0.0	0.1
Net cash (used in) provided by financing activities	(39.0)	132.2
Net change in cash, cash equivalents and restricted cash	288.8	(106.3)
Cash, cash equivalents and restricted cash at beginning of period (1)	1,417.6	954.3
Cash, cash equivalents and restricted cash at end of period (2)	1,706.4	$ 848.0
Cash and cash equivalents	892.2
Restricted Cash	$ 814.2