Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Summary of RSU Activity (Detail)

v3.10.0.1
Stockholders' Equity - Summary of RSU Activity (Detail) - Unvested RSUs - $ / shares
9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Shares, Unvested as of December 31, 2017 1,685,000  
Shares, Granted 836,487  
Shares, Forfeited (469,613)  
Shares, Vested (619,983)  
Shares, Unvested as of June 30, 2018 1,431,891  
Shares, Vested and unreleased 2,617  
Shares, Outstanding as of June 30, 2018 1,434,508  
Weighted Average Grant Date Fair Value, Unvested as of December 31, 2017 $ 16.90  
Weighted Average Grant Date Fair Value, Granted 34.61 $ 15.07
Weighted Average Grant Date Fair Value, Forfeited 20.93  
Weighted Average Grant Date Fair Value, Vested 17.33  
Weighted Average Grant Date Fair Value, Unvested as of June 30, 2018 $ 31.86  
Outstanding as of September 30, 2018 1,434,508