Net Income (Loss) per Share Attributable to Common Stockholders - Antidilutive Securities (Details) - shares shares in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 29, 2018 |
Sep. 30, 2017 |
Sep. 29, 2018 |
Sep. 30, 2017 |
|
| Stock options | ||||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||||
| Antidilutive securities (shares) | 568 | 1,385 | 843 | 1,334 |
| Restricted stock units | ||||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||||
| Antidilutive securities (shares) | 1,048 | 184 | 808 | 108 |
| Series A Redeemable Convertible Preferred Stock (as converted to common stock) | ||||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||||
| Antidilutive securities (shares) | 4,983 | 5 | 4,983 | 5 |