Fair value measurements and financial instruments - Financial Instruments Recorded at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, current	$ 2.2	$ 2.9
Marketable securities, noncurrent	5.6	6.1
Quoted prices in active markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, noncurrent	2.8	2.9
Significant other observable input (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, current	2.2	2.9
Marketable securities, noncurrent	$ 2.8	$ 3.2