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Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Millions	Jun. 30, 2026	Jun. 05, 2026	Dec. 31, 2025
Debt Instrument [Line Items]
Debt issuance cost	$ (44.3)		$ (29.1)
Total long-term debt	3,963.6		3,355.4
Less: debt maturing within one year	9.3		585.6
Total long-term debt, less current portion	3,954.3		2,769.8
Pollution control and industrial revenue bonds (less unamortized discounts of $0.1 in each period)
Debt Instrument [Line Items]
Unamortized discount	$ 0.1		0.1
Interest Rate Percentage	6.45%
Long-term debt, gross	$ 49.9		49.9
Senior notes (less unamortized discount of $1.3 and $1.4, respectively)
Debt Instrument [Line Items]
Unamortized discount	1.3		1.4
Long-term debt, gross	$ 1,998.7		2,498.6
Senior notes (less unamortized discount of $1.3 and $1.4, respectively) \| Minimum
Debt Instrument [Line Items]
Interest Rate Percentage	3.50%
Senior notes (less unamortized discount of $1.3 and $1.4, respectively) \| Maximum
Debt Instrument [Line Items]
Interest Rate Percentage	6.40%
Senior Secured Notes
Debt Instrument [Line Items]
Interest Rate Percentage	8.00%	8.00%
Long-term debt, gross	$ 1,200.0		0.0
Subordinated Notes
Debt Instrument [Line Items]
Interest Rate Percentage	8.45%
Long-term debt, gross	$ 750.0		750.0
Foreign debt
Debt Instrument [Line Items]
Interest Rate Percentage	12.30%
Long-term debt, gross	$ 9.3		$ 86.0