Commitments and contingencies - Changes in Accrued Environmental Remediation and Related Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Environmental Remediation Obligations [Abstract]
Balance at the beginning of the period	$ 96.9	$ 97.3	$ 97.6
Additions charged to expense, net	(19.2)	2.5	1.7
Payments, net	(3.1)	(2.9)	(2.0)
Balance at the end of the period	74.6	96.9	97.3
Amounts recognized in the Consolidated Balance Sheet at the end of the year:
Current liabilities	59.7	3.7	3.8
Noncurrent liabilities	$ 14.9	$ 93.2	$ 93.5
Environmental Loss Contingency, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other Liabilities Noncurrent	Other Liabilities Noncurrent	Other Liabilities Noncurrent
Total	$ 74.6	$ 96.9	$ 97.3
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]	Accrued Liabilities, Current, Other Liabilities Noncurrent	Accrued Liabilities, Current, Other Liabilities Noncurrent	Accrued Liabilities, Current, Other Liabilities Noncurrent