Fair Value Measurements - Summary of Changes of Liabilities for Sale of Future Royalties (Details) - BVF Partners L.P. - BVF Agreement - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 21	$ 19
Interest accretion	0	1
Ending balance	$ 21	$ 20

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration