Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Summary of Stock Option Activity (Details)

v3.8.0.1
Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Stock options, Outstanding, balance 12,897 12,795  
Stock options, Granted 5,266 3,674  
Stock options, Exercised (687) (1,852)  
Stock options, Cancelled (1,208) (1,720)  
Stock options, Outstanding, Balance 16,268 12,897 12,795
Stock options, Options vested and exercisable 8,169    
Stock options, Options vested and expected to vest 14,833    
Weighted-average exercise price, Outstanding, Balance $ 5.94 $ 5.89  
Weighted-average exercise price, Granted 5.17 5.73  
Weighted-average exercise price, Exercised 2.96 2.94  
Weighted-average exercise price, Cancelled 7.62 8.37  
Weighted-average exercise price, Outstanding, Balance 5.70 $ 5.94 $ 5.89
Weighted-average exercise price, Options vested and exercisable 5.56    
Weighted-average exercise price, Options vested and expected to vest $ 5.68    
Weighted-average remaining contractual life, Options outstanding 7 years 4 months 28 days 7 years 5 months 27 days 7 years 9 months 26 days
Weighted-average remaining contractual life, Options vested and exercisable 6 years 18 days    
Weighted-average remaining contractual life, Options vested and expected to vest 7 years 7 days    
Aggregate intrinsic value, Options outstanding $ 14,832 $ 9,625 $ 76
Aggregate intrinsic value, Options vested and exercisable 10    
Aggregate intrinsic value, Options vested and expected to vest $ 14