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Investment in Inex Bio, Inc - Additional Information (Detail) - USD ($) |  | 1 Months Ended | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | --- | ---
Mar. 30, 2015 | Apr. 30, 2015 | May. 31, 2012 | Apr. 30, 2012 | Sep. 30, 2015 | Sep. 30, 2014 | Sep. 30, 2015 | Sep. 30, 2014 | Mar. 31, 2014
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Number of shares acquired during period |  |  | 57,000 |  |  |  |  |  |
Stock issued during period, value, acquisitions |  |  | $ 249,000 |  |  |  |  |  |
Outstanding shares acquired, percentage |  |  | 22.20% |  |  |  |  |  |
Percentage of fully diluted shares acquired |  |  | 17.40% |  |  |  |  |  |
Percentage of equity owned by partners |  |  |  |  |  |  |  |  | 7.00%
Proceeds from exercise of warrants |  |  |  |  |  |  | $ 7,340,000 |  |
Stock-based compensation expense |  |  |  |  | $ 36,103,000 | $ 29,000 | $ 140,667,000 | $ 196,000 |
Common Class A |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Stock price of warrants |  |  |  |  | $ 2.44 |  | $ 2.44 |  |
Inex Bio Holdings |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Percentage of equity owned by partners |  |  |  |  | 50.00% |  | 50.00% |  |
Payments to acquire business |  |  |  |  |  |  | $ 6,518,000 |  |
Stock price of warrants | $ 10.72 |  |  |  |  |  |  |  |
Term of warrants after closing date of the purchase agreement | 15 days |  |  |  |  |  |  |  |
Expected volatility rate | 80.00% |  |  |  |  |  |  |  |
Stock-based compensation expense |  |  |  |  |  |  | 22,747,000 |  |
Cash based compensation |  |  |  |  |  |  | $ 5,418,000 |  |
Inex Bio Holdings | Common Class A |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Warrants issued to acquire shares |  |  |  |  |  |  | 2,609,520 |  |
Common stock exercise price |  |  |  |  | $ 2.00 |  | $ 2.00 |  |
Proceeds from exercise of warrants |  | $ 5,215,000 |  |  |  |  |  |  |
Eragon Ventures, LLC |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Number of shares acquired during period |  |  |  |  |  |  | 220,000 |  |
Percentage of equity owned by partners |  |  |  |  | 50.00% |  | 50.00% |  |
Percentage shares acquired |  |  |  |  | 67.30% |  | 67.30% |  |
Payments to acquire business |  |  |  |  |  |  | $ 1,100,000 |  |
Other Owner Of Inex Bio Inc |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Payments to acquire business |  |  |  |  |  |  | $ 1,482,000 |  |
Stock price of warrants | $ 10.72 |  |  |  |  |  |  |  |
Term of warrants after closing date of the purchase agreement | 15 days |  |  |  |  |  |  |  |
Expected volatility rate | 80.00% |  |  |  |  |  |  |  |
Reacquired rights period |  |  |  |  |  |  | 4 years |  |
Other Owner Of Inex Bio Inc | Common Class A |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Warrants issued to acquire shares |  |  |  |  |  |  | 593,072 |  |
Common stock exercise price |  |  |  |  | $ 2.00 |  | $ 2.00 |  |
Proceeds from exercise of warrants |  | $ 1,185,000 |  |  |  |  |  |  |
Inex license agreement |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Milestone payment amount |  |  |  |  |  |  | $ 0 | $ 0 |
Percentage of royalty on net sales |  |  |  | 5.00% |  |  |  |  |
Inex license agreement | Up front fee |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
License fees received |  |  |  | $ 300,000 |  |  |  |  |
Inex license agreement | Maximum |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Milestone payment amount |  |  |  | $ 775,000 |  |  |  |  |

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