Common Stock and Stock-Based Compensation - Schedule of Stock-Based Compensation Expense Related to Options (Details) - Employees And Nonemployees Stock Option - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] | ||||
Stock-based compensation expense | $ 8,270 | $ 4,744 | $ 19,736 | $ 11,538 |
Research and Development | ||||
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] | ||||
Stock-based compensation expense | 4,399 | 2,146 | 9,842 | 5,602 |
General and Administrative | ||||
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] | ||||
Stock-based compensation expense | $ 3,871 | $ 2,598 | $ 9,894 | $ 5,936 |