Agreements with Royalty Pharma - Schedule Represents Allocation of Transaction Consideration on a Relative Fair Value Basis to the Liability and the Common Stock (Detail) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
|
| RP Aficamten Liability [Member] | ||
| Royalty Liability [Line Items] | ||
| Liabilities related to revenue participation right purchase agreements, net beginning balance | $ 320,764 | $ 262,599 |
| Interest accretion | 18,816 | 14,037 |
| Amortization of issuance costs | 0 | 0 |
| Liabilities related to revenue participation right purchase agreements, net ending balance | 339,580 | 276,636 |
| RPOM Liability [Member] | ||
| Royalty Liability [Line Items] | ||
| Liabilities related to revenue participation right purchase agreements, net beginning balance | 199,795 | 199,593 |
| Interest accretion | 0 | 41 |
| Amortization of issuance costs | 0 | 26 |
| Liabilities related to revenue participation right purchase agreements, net ending balance | $ 199,795 | $ 199,660 |