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Stock-Based Compensation - Stock Based Compensation Expenses Related to Statement of Operations (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2015 | Sep. 30, 2014 | Sep. 30, 2015 | Sep. 30, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |  |
Stock-based compensation expense | $ 36,103 | $ 29 | $ 140,667 | $ 196
Director Related to Inex Bio, Inc | Warrants for Class A Common Stock to an Officer |  |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |  |
Stock-based compensation expense |  |  | 22,747 |
Officer | Warrants for Class A Common Stock to an Officer |  |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |  |
Stock-based compensation expense | 4,745 |  | 80,663 |
Employee Stock Option |  |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |  |
Stock-based compensation expense | 16,424 | 26 | 20,033 | 190
Non Employee Stock Options |  |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |  |
Stock-based compensation expense | 784 | 3 | 3,074 | 6
Outstanding Restricted Stock Units |  |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |  |
Stock-based compensation expense | 14,150 |  | 14,150 |
Research and Development |  |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |  |
Stock-based compensation expense | 364 |  | 1,140 |
Selling, General and Administrative |  |  |  |
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] |  |  |  |
Stock-based compensation expense | $ 35,739 | $ 29 | $ 139,527 | $ 196

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- Definition The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 + Details
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