Fair Value Measurements - Summary of Changes of Liabilities for Sale of Future Royalties (Details) - BVF Partners L.P. - BVF Agreement - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
| Beginning balance | $ 19 | $ 17 |
| Interest accretion | 2 | 2 |
| Ending balance | $ 21 | $ 19 |