Financial Instruments - Summary of financial assets with maturities of less than 90 days included within cash and cash equivalents (Details) - USD ($) $ in Millions |
Sep. 30, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Net Investment Income [Line Items] | ||
| Cash equivalents, at carrying value | $ 3,398.8 | $ 1,664.9 |
| Commercial Paper | ||
| Net Investment Income [Line Items] | ||
| Cash equivalents, at carrying value | 79.2 | 0.0 |
| Money market funds | ||
| Net Investment Income [Line Items] | ||
| Cash equivalents, at carrying value | 3,116.7 | 1,664.9 |
| Short-term debt securities | ||
| Net Investment Income [Line Items] | ||
| Cash equivalents, at carrying value | $ 202.9 | $ 0.0 |