Summary of Significant Accounting Policies - Net Income per Share Schedule of Weighted Average Number of Shares (Details) - shares
shares in Thousands |
3 Months Ended |
Mar. 31, 2018 |
Mar. 31, 2017 |
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
| Weighted average shares outstanding (in shares) |
34,085
|
33,747
|
| Less: Weighted average unvested restricted shares subject to repurchase (in shares) |
15
|
41
|
| Weighted average common shares outstanding; basic (in shares) |
34,070
|
33,706
|
| Weighted average common shares outstanding; basic (in shares) |
34,070
|
33,706
|
| Plus: Weighted average options, restricted stock units and restricted shares used to compute diluted net income per share (in shares) |
1,230
|
1,059
|
| Weighted average common shares outstanding; diluted (in shares) |
35,300
|
34,765
|
| Shares excluded from net loss per share attributable to common stockholders (in shares) |
22
|
33
|
| PSUs and PSOs |
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
| Shares excluded from net loss per share attributable to common stockholders (in shares) |
607
|
784
|