Liability Related to Sale of Future Royalties (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | 70 Months Ended | |||
|---|---|---|---|---|---|---|
Feb. 24, 2012 |
Sep. 30, 2020 |
Sep. 30, 2019 |
Sep. 30, 2020 |
Sep. 30, 2019 |
Dec. 31, 2017 |
|
| Liability Related to Sale of Future Royalties [Line Items] | ||||||
| Non-cash royalty revenue related to sale of future royalties | $ 28,001 | $ 27,585 | ||||
| Non-cash interest expense on liability related to sale of future royalties | $ (8,425) | $ (5,813) | $ (22,084) | $ (17,853) | ||
| Annual interest rate | 20.20% | 17.00% | ||||
| Prospective interest rate | 48.00% | |||||
| Purchase and Sale Agreement with RPI | ||||||
| Liability Related to Sale of Future Royalties [Line Items] | ||||||
| Proceeds from sale of royalty rights | $ 124,000 | |||||
| Transaction costs related to sale of potential future royalties | $ 4,400 | |||||