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Liability Related to Sale of Future Royalties - Additional Information (Detail) - USD ($) $ in Thousands |  | 3 Months Ended | 70 Months Ended
--- | --- | --- | ---
Feb. 24, 2012 | Mar. 31, 2018 | Mar. 31, 2017 | Dec. 31, 2017
Liability Related to Sale of Future Royalties [Line Items] |  |  |  |
Non-cash royalty revenue related to sale of future royalties |  | $ 6,920 | $ 6,663 |
Non-cash interest expense on liability related to sale of future royalties |  | $ 5,019 | $ 4,552 |
Annual interest rate |  | 17.60% |  | 17.00%
Prospective interest rate |  | 21.00% |  |
Purchase and Sale Agreement with RPI [Member] |  |  |  |
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 |  |  |

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- Definition Estimated annual interest rate over life of royalty liability. + References No definition available. + Details
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- Definition Liability related to sale of future royalties. + References No definition available. + Details
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- Definition Non-cash interest expense related to sale of royalties. + References No definition available. + Details
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- Definition Non cash royalty revenue related to sale future royalties. + References No definition available. + Details
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- Definition Proceeds from sale of potential future royalties gross. + References No definition available. + Details
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- Definition Prospective interest rate percentage. + References No definition available. + Details
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- Definition Transaction costs related to sale of potential future royalties. + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Details
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Period Type: |