Summary of Significant Accounting Policies - Schedule of Common Stock Equivalents, Excluded from Computation of Diluted Net Loss per Share (Detail) - shares
|
12 Months Ended |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total options, restricted stock units exercisable or convertible into common stock |
2,901,964
|
2,201,531
|
15,984,289
|
| Stock Options to Purchase Common Stock [Member] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total options, restricted stock units exercisable or convertible into common stock |
2,861,011
|
2,146,927
|
1,124,116
|
| Restricted Common Stock Units [Member] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total options, restricted stock units exercisable or convertible into common stock |
40,953
|
54,604
|
|
| Series A, B-1, B-2, C,D-1, D-2, D-3 and E Redeemable Convertible Preferred Stock [Member] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total options, restricted stock units exercisable or convertible into common stock |
|
|
14,860,173
|