Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	$ 305.4	$ 315.6	$ 337.1
Amortization of deferred financing fees	15.4	12.6	11.9
Accretion of customer supply agreement	2.5	2.6	2.2
Employee stock compensation expense	38.1	29.2	36.6
(Gain) loss from derivative instruments	(3.6)	(0.5)	17.1
(Gain) loss from foreign currency transactions	(12.1)	7.5	(18.9)
Gains (Losses) on Extinguishment of Debt	0.0	11.8	2.6
Payment for Debt Extinguishment or Debt Prepayment Cost	0.0	(11.8)	(2.6)
Loss on disposition of assets	2.0	6.9	1.1
Deferred taxes	3.7	18.1	8.5
Pension and other post-retirement plans (income) expense	(11.5)	55.1	37.1
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(1.6)	186.6	19.5
Grant liability amortization	(1.2)	(1.1)	(1.5)
Equity in net (income) loss of affiliates	(0.2)	0.3	1.6
Increase (Decrease) in Forward Position	793.0	(194.9)	(89.7)
Changes in assets and liabilities
Accounts receivable, net	198.0	(96.6)	(39.4)
Inventory, net	(152.4)	(295.1)	(118.2)
Increase (Decrease) in Contract with Customer, Asset	(280.3)	(18.0)	(63.9)
Accounts payable and accrued liabilities	(49.9)	213.8	220.7
Profit sharing/deferred compensation	45.7	(25.0)	(22.5)
Advance payments	(0.2)	114.1	(133.2)
Income taxes receivable/payable	(1.6)	(3.4)	9.5
Increase (Decrease) in Contract with Customer, Liability	100.3	(3.0)	(30.4)
Other	37.4	4.3	0.1
Net cash used in operating activities	(1,120.9)	(225.8)	(394.6)
Investing activities
Purchase of property, plant and equipment	(152.5)	(148.0)	(121.6)
Payments to Acquire Businesses, Net of Cash Acquired	0.0	0.0	(31.3)
Payments for (Proceeds from) Other Investing Activities	(0.1)	(0.2)	2.6
Net cash used in investing activities	(152.4)	(147.8)	(155.5)
Financing activities
Proceeds from Issuance of Senior Long-term Debt	0.0	1,200.0	900.0
Proceeds from revolving credit facility	1.6	5.4	0.0
Payments on revolving credit facility	(1.6)	(0.6)	0.0
Principal payments of debt	(62.6)	(64.1)	(47.6)
Repayments of Debt	(5.9)	(5.9)	(6.0)
Early Repayment of Senior Debt	0.0	(1,200.0)	(779.2)
Payment, Tax Withholding, Share-based Payment Arrangement	(17.1)	(6.6)	(7.2)
Proceeds from Stock Plans	7.6	6.3	3.9
Debt issuance and financing costs	(11.0)	(28.5)	(32.3)
Proceeds from Other Debt	764.0	180.0	0.0
Payments of Dividends	0.0	0.0	(4.2)
Proceeds from Noncontrolling Interests	0.0	0.0	3.7
Net cash provided by (used in) financing activities	994.5	531.6	(261.0)
Proceeds from Issuance of Secured Debt	360.5	242.7	0.0
Net (decrease) increase in cash, cash equivalents, and restricted cash for the period	(279.4)	167.5	(820.0)
Cash, cash equivalents, and restricted cash, end of period	537.0	823.5	658.6
Restricted Cash, Current	0.0	0.1	0.2
Restricted Cash and Investments, Noncurrent	29.5	22.3	19.6
Supplemental information
Interest paid	329.5	285.3	222.5
Proceeds from Income Tax Refunds	(1.6)
Income taxes paid		(2.8)	(15.2)
Property acquired through capital leases	9.6	31.7	49.6
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	566.5	845.9	678.4
Gain (Loss) on Contract Termination	(1.5)	(1.8)	(21.9)
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations	(0.6)	9.5	(8.9)
Interest paid	329.5	285.3	222.5
Proceeds from Income Tax Refunds	1.6
Income taxes paid		2.8	15.2
Lease Obligation Incurred	9.6	31.7	49.6
Payments to Acquire Businesses, Net of Cash Acquired	0.0	0.0	31.3
Payments of Dividends	0.0	0.0	4.2
Proceeds from Noncontrolling Interests	0.0	0.0	3.7
Proceeds from (Payments for) Other Financing Activities	(1.0)	0.0	0.0
Payment, Tax Withholding, Share-based Payment Arrangement	17.1	6.6	7.2
Proceeds from Stock Plans	7.6	6.3	3.9
Gains (Losses) on Extinguishment of Debt	0.0	(11.8)	(2.6)
Payment for Debt Extinguishment or Debt Prepayment Cost	0.0	11.8	2.6
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	0.0	(2.4)	0.0
Gain on settlement of New Market Tax Credit incentive program	(5.7)	0.0	0.0
Increase (Decrease) in Other Operating Assets and Liabilities, Net	(37.4)	(4.3)	(0.1)
Increase (Decrease) in Deferred Liabilities	(3.6)	53.6	(14.4)
Proceeds from Issuance of Common Stock	0.0	220.7	0.0
Proceeds from Other Debt	764.0	180.0	0.0
Repayments of Other Debt	(40.0)	0.0	0.0
Repayments of Long-term Debt	62.6	64.1	47.6
Repayments of Debt	5.9	5.9	6.0
Repayments of Lines of Credit	1.6	0.6	0.0
Early Repayment of Senior Debt	0.0	1,200.0	779.2
Asset Acquisition, Consideration Transferred, Contingent Consideration	0.0	(6.0)	0.0
Payments of Financing Costs	11.0	28.5	32.3
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations	(0.6)	9.5	(8.9)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(2,139.0)	(616.1)	(546.2)
Asset Impairment Charges	2.0	0.0	0.0
Settlement of financing instrument	$ 0.0	$ 0.0	$ (289.5)