Summary of Significant Accounting Policies - Revenue Recognition, Share-Based Compensation, Foreign Currencies and Governmental Assistance (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) item	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Revenue Recognition
Number of performance obligations from sales of metal products | item	1
Shipping and handling costs included in operating expenses	$ 550.5	$ 525.9	$ 509.7
Share-Based Compensation
Stock-based compensation expense	56.8	65.0	65.3
Foreign Currencies
Net gain (loss) resulting from foreign currency transactions	$ 1.9	$ (1.3)	$ (6.2)
Governmental Assistance
Government assistance transaction (in years)	13 years
Government assistance, assets associated with the EDBs	$ 37.3
Government Assistance, Asset, Statement of Financial Position [Extensible Enumeration]	Property, Plant and Equipment, Net.
Government assistance, liabilities associated with the EDBs	$ 37.3
Government Assistance, Liability, Statement of Financial Position [Extensible Enumeration]	Operating Lease, Liability, Noncurrent
Toll processing
Revenue Recognition
Number Of Days To Perform Services	1 day