Debt - Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Debt issuance cost	$ (28.0)	$ (20.4)
Total long-term debt	3,358.9	3,104.0
Less: debt maturing within one year	88.4	76.1
Total long-term debt, less current portion	3,270.5	3,027.9
Pollution control and industrial revenue bonds (less unamortized discounts of $0.1 and $0.1, respectively)
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 $1.4 and $1.6, respectively)
Debt Instrument [Line Items]
Unamortized discount	1.4	1.6
Long-term debt, gross	$ 2,498.6	2,998.4
Senior notes (less unamortized discount of $1.4 and $1.6, respectively) \| Minimum
Debt Instrument [Line Items]
Interest Rate Percentage	3.20%
Senior notes (less unamortized discount of $1.4 and $1.6, respectively) \| Maximum
Debt Instrument [Line Items]
Interest Rate Percentage	6.40%
Subordinated Notes
Debt Instrument [Line Items]
Interest Rate Percentage	8.45%
Long-term debt, gross	$ 750.0	0.0
Revolving Credit Facility
Debt Instrument [Line Items]
Letters of credit outstanding amount	209.8
Line of credit, remaining borrowing capacity	$ 808.4
Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Interest Rate Percentage	6.80%
Long-term debt, gross	$ 0.0	0.0
Foreign debt
Debt Instrument [Line Items]
Long-term debt, gross	$ 88.4	$ 76.1
Foreign debt \| Minimum
Debt Instrument [Line Items]
Interest Rate Percentage	12.60%
Foreign debt \| Maximum
Debt Instrument [Line Items]
Interest Rate Percentage	17.10%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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