Fair value measurements and financial instruments - Financial Instruments Recorded at Fair Value (Details) - USD ($) $ in Millions |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
| Marketable securities, current | $ 2.7 | $ 2.9 |
| Marketable securities, noncurrent | 6.5 | 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 | 3.0 | 2.9 |
| Significant other observable input (Level 2) | ||
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
| Marketable securities, current | 2.7 | 2.9 |
| Marketable securities, noncurrent | $ 3.5 | $ 3.2 |