Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Summary of RSU Activity (Detail)

v3.19.1
Stockholders' Equity - Summary of RSU Activity (Detail) - Unvested RSUs - $ / shares
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Shares, Unvested as of December 31, 2018 1,405,460  
Shares, Granted 814,493  
Shares, Forfeited (45,206)  
Shares, Vested (314,373)  
Shares, Unvested as of March 31, 2019 1,860,374  
Shares, Vested and unreleased 0  
Shares, Outstanding as of March 31, 2019 1,860,374  
Weighted Average Grant Date Fair Value, Unvested as of December 31, 2018 $ 26.94  
Weighted Average Grant Date Fair Value, Granted 38.42 $ 35.80
Weighted Average Grant Date Fair Value, Forfeited 33.82  
Weighted Average Grant Date Fair Value, Vested 23.59  
Weighted Average Grant Date Fair Value, Unvested as of March 31, 2019 $ 32.36