Net Loss per Common Share - Antidilutive Securities Excluded From Computation of Diluted Net Loss per Common Share (Detail) - shares |
6 Months Ended | |
|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
|
| Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | ||
| Antidilutive securities excluded from computation of earnings per share | 7,525,982 | 6,295,579 |
| Unvested RSUs | ||
| Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | ||
| Antidilutive securities excluded from computation of earnings per share | 1,797,702 | 1,801,397 |
| Vested and Unvested Options | ||
| Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | ||
| Antidilutive securities excluded from computation of earnings per share | 5,718,914 | 4,482,620 |
| ESPP Share Purchase Rights | ||
| Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | ||
| Antidilutive securities excluded from computation of earnings per share | 9,366 | 11,562 |