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Collaboration and Other Agreements - Provention (Details) |  | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | ---
May 31, 2018 USD ($) performance_obligation $ / shares shares | Sep. 30, 2019 USD ($) | Sep. 30, 2018 USD ($) | Sep. 30, 2019 USD ($) | Sep. 30, 2018 USD ($) | Dec. 31, 2018 USD ($)
Collaboration And Other Agreements [Line Items] |  |  |  |  |  |
Revenues |  | $ 18,741,000 | $ 20,798,000 | $ 38,996,000 | $ 44,327,000 |
Fair Value |  | $ 86,276,000 |  | 86,276,000 |  |
Provention |  |  |  |  |  |
Collaboration And Other Agreements [Line Items] |  |  |  |  |  |
Number of performance obligations | performance_obligation | 2 |  |  |  |  |
Collaborative agreement transaction price | $ 6,100,000 |  |  |  |  |
Number of shares available under warrants (in shares) | shares | 2,432,688 |  |  |  |  |
License Agreement | Provention | Provention PRV-3279 |  |  |  |  |  |
Collaboration And Other Agreements [Line Items] |  |  |  |  |  |
Warrant to purchase shares of common stock, exercise price (in dollars per share) | $ / shares | $ 2.50 |  |  |  |  |
Potential development and regulatory milestone payments under agreement | $ 65,000,000.0 |  |  |  |  |
Potential commercial milestone payments under agreement | $ 225,000,000.0 |  |  |  |  |
Asset Purchase Agreement | Provention | Provention PRV-031 |  |  |  |  |  |
Collaboration And Other Agreements [Line Items] |  |  |  |  |  |
Warrant to purchase shares of common stock, exercise price (in dollars per share) | $ / shares | $ 2.50 |  |  |  |  |
Potential development and regulatory milestone payments under agreement | $ 170,000,000.0 |  |  |  |  |
Potential commercial milestone payments under agreement | 225,000,000.0 |  |  |  |  |
Potential milestone payments to third parties | $ 1,300,000 |  |  |  |  |
Revenues From License Agreements | Provention |  |  |  |  |  |
Collaboration And Other Agreements [Line Items] |  |  |  |  |  |
Revenues |  |  | $ 6,100,000 |  |  |
Warrant |  |  |  |  |  |
Collaboration And Other Agreements [Line Items] |  |  |  |  |  |
Increase in valuation |  |  |  | $ 20,500,000 |  |
Fair Value Measurements, Recurring Basis | Warrant |  |  |  |  |  |
Collaboration And Other Agreements [Line Items] |  |  |  |  |  |
Fair Value |  |  |  |  |  | $ 1,890,000

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