UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Cash Flows From Operating Activities
Net loss	$ (120.6)	$ (79.7)
Loss from discontinued operations, net of income taxes	0.8	2.0
Loss from continuing operations, net of income taxes	(119.8)	(77.7)
Adjustments to reconcile loss from continuing operations, net of income taxes to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization	72.9	68.3
Noncash interest expense, net	3.8	4.9
Deferred income taxes	(6.4)	(0.4)
Noncash share-based compensation	2.0	1.8
Net (gain) loss on disposals	(4.9)	0.6
Net loss (gain) on early debt extinguishment	23.5	(3.5)
(Income) loss from equity affiliates	(44.7)	0.9
Foreign currency option contracts	(3.3)	2.9
Changes in current assets and liabilities:
Accounts receivable	(6.9)	77.0
Inventories	(42.4)	20.3
Other current assets	(80.0)	1.6
Accounts payable and accrued expenses	(28.4)	(15.4)
Collateral arrangements	(28.7)	(5.3)
Asset retirement obligations	4.7	8.1
Workers’ compensation obligations	(0.6)	0.6
Postretirement benefit obligations	(15.9)	(13.4)
Pension obligations	(0.6)	2.8
Other, net	3.2	0.0
Net cash (used in) provided by continuing operations	(272.5)	74.1
Net cash used in discontinued operations	(1.2)	(3.1)
Net cash (used in) provided by operating activities	(273.7)	71.0
Cash Flows From Investing Activities
Additions to property, plant, equipment and mine development	(29.7)	(50.3)
Changes in accrued expenses related to capital expenditures	(7.0)	(11.4)
Proceeds from disposal of assets, net of receivables	3.6	0.9
Contributions to joint ventures	(126.6)	(136.1)
Distributions from joint ventures	148.2	102.4
Cash receipts from Middlemount Coal Pty Ltd and other related parties	47.2	2.3
Other, net	(0.5)	(1.0)
Net cash provided by (used in) investing activities	35.2	(93.2)
Cash Flows From Financing Activities
Proceeds from long-term debt	545.0	0.0
Repayments of long-term debt	(599.9)	(40.2)
Payment of debt issuance and other deferred financing costs	(19.2)	(22.5)
Proceeds from common stock issuances, net of costs	222.0	0.0
Repurchase of employee common stock relinquished for tax withholding	(2.0)	(0.6)
Distributions to noncontrolling interests	(13.8)	(0.1)
Other, net	0.1	0.1
Net cash provided by (used in) financing activities	132.2	(63.3)
Net change in cash, cash equivalents and restricted cash	(106.3)	(85.5)
Cash, cash equivalents and restricted cash at beginning of period	954.3	709.2	$ 709.2
Cash, cash equivalents and restricted cash at end of period	$ 848.0	$ 623.7	$ 954.3