Annual report pursuant to Section 13 and 15(d)

Stock-based Compensation Plans and Awards - Schedule of stock option activity (Details)

v3.6.0.2
Stock-based Compensation Plans and Awards - Schedule of stock option activity (Details) - Stock options - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Outstanding Stock Options    
Balance at the beginning of the period (in shares) 12,815,891  
Granted (in shares) 0  
Exercised (in shares) (1,588,781)  
Forfeited (in shares) (1,790,730)  
Balance at the end of the period (in shares) 9,436,380 12,815,891
Vested and exercisable at the end of the period (in shares) 8,108,519  
Expected to vest at the end of the period (in shares) 1,241,887  
Weighted-Average Exercise Price    
Balance at the beginning of the period (in dollars per share) $ 7.15  
Granted (in dollars per share) 0  
Exercised (in dollars per share) 2.18  
Forfeited (in dollars per share) 19.02  
Balance at the end of the period (in dollars per share) 5.74 $ 7.15
Vested and exercisable at the end of the period (in dollars per share) 5.40  
Expected to vest at the end of the period (in dollars per share) $ 7.94  
Weighted-Average Remaining Contractual Term (in years)    
Outstanding at the beginning of the period 14 days 1 year 1 month 2 days
Outstanding at the end of the period 14 days 1 year 1 month 2 days
Vested and exercisable at the end of the period 9 days  
Expected to vest at the end of the period 1 year 6 months  
Aggregate Intrinsic Value    
Aggregate intrinsic value beginning of the period $ 77,752 $ 101,151
Aggregate intrinsic value end of the period 77,752 $ 101,151
Vested and exercisable at the end of the period 68,656  
Expected to vest at the end of the period $ 8,403  
Fair value per share of common stock (in dollars per share) $ 13.04 $ 13.41