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Collaboration Agreements, License Agreement and Revenues - Drug Product Revenue - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended |
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Sep. 30, 2025 | Mar. 31, 2025 | Dec. 31, 2024 | Sep. 30, 2024 | Jun. 30, 2024 | Mar. 31, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Dec. 31, 2024 | Oct. 31, 2025
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Deferred Revenue | $ 5,104 |  | $ 27,290 |  |  |  | $ 5,104 |  | $ 27,290 |
Drug product revenue recognized | 1,076 |  |  | $ 123 |  |  | 5,163 | $ 26,486 |  |
Other long-term liabilities | 98 |  | 822 |  |  |  | 98 |  | 822 |
Astra Zeneca Agreements [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Drug product revenue recognized | 165,300 |  |  | 42,200 |  |  | 218,600 | 115,300 |  |
Drug Product Revenue, Net [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Drug product revenue recognized | 957 |  |  | (262) |  |  | 4,767 | 24,954 |  |
Drug Product Revenue, Net [Member] | Astellas Agreement [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Drug product revenue recognized | 1,000 |  |  | (300) |  |  | 4,800 | (700) |  |
Drug Product Revenue, Net [Member] | Europe [Member] | Astellas Agreement [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Drug product revenue recognized | 1,335 |  |  | 1,093 |  |  | 3,321 | 3,209 |  |
Drug Product Revenue, Net [Member] | Europe [Member] | Astellas Europe Agreement [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Burdened manufacturing costs |  |  | 600 |  |  |  |  |  |  |
Drug Product Revenue, Net [Member] | Japan [Member] | Astellas Agreement [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Drug product revenue recognized | (378) |  |  | (1,355) |  |  | 1,446 | (3,926) |  |
Accrued liabilities | 1,000 |  | 2,500 |  |  |  | 1,000 |  | 2,500 |
Other long-term liabilities |  |  | 600 |  |  |  |  |  | 600 |
Drug Product Revenue, Net [Member] | API Shipment [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Drug product revenue recognized | 400 | $ 1,800 |  | 1,400 | $ 400 | $ 2,200 |  |  |  |
Bulk Drug Product [Member] | Astellas Europe Agreement [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Deferred Revenue |  |  | 4,400 |  |  |  |  |  | 4,400 |
Bulk Drug Product [Member] | Europe [Member] | Astellas Europe Agreement [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Drug product revenue recognized |  |  |  |  |  |  | 900 |  | 7,200 |
Accrued liabilities | 11,400 |  | $ 10,500 |  |  |  | 11,400 |  | $ 10,500 |
Bulk Drug Product [Member] | Europe [Member] | Astellas Europe Agreement [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Accrued liabilities |  |  |  |  |  |  |  |  |  | $ 7,100
Bulk Drug Product [Member] | Europe [Member] | Astellas Europe Agreement [Member] | Royalty Revenue [Member] |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |
Royalty revenue recognized as drug product revenue | $ 1,300 |  |  | $ 1,100 |  |  | $ 3,300 | $ 3,200 |  |

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