Quarterly report pursuant to Section 13 or 15(d)

Accounting for Shared-based Payments - Schedule of Stock Option Activity (Details)

v3.10.0.1
Accounting for Shared-based Payments - Schedule of Stock Option Activity (Details) - Stock Options - USD ($)
$ / shares in Units, $ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2017
Number of Options    
Balance outstanding at the beginning of period (in shares) 29,868,291  
Granted (in shares) 7,917,700  
Exercised (in shares) (1,805,081)  
Forfeited (in shares) (2,680,222)  
Balance outstanding at the end of period (in shares) 33,300,688 29,868,291
Exercisable at the end of the period (in shares) 22,056,762  
Weighted Average Exercise Price Per Share    
Balance outstanding at the beginning of period (in dollars per share) $ 3.83  
Granted (in dollars per share) 2.12  
Exercised (in dollars per share) 0.56  
Forfeited (in dollars per share) 2.78  
Balance outstanding at the end of period (in dollars per share) 3.61 $ 3.83
Exercisable at the end of the period (in dollars per share) $ 4.00  
Intrinsic Value    
Balance outstanding $ 714 $ 5,346
Exercised 2,153  
Exercisable at the end of the period $ 692  
Weighted Average Remaining Contractual Term    
Balance outstanding 6 years 7 months 6 days 6 years 1 month 2 days
Exercisable at the end of the period 5 years 4 months 28 days  
Withheld in period (in shares) 428,147  
Minimum    
Weighted Average Exercise Price Per Share    
Balance outstanding at the beginning of period (in dollars per share) $ 0.44  
Granted (in dollars per share) 1.56  
Exercised (in dollars per share) 0.50  
Forfeited (in dollars per share) 0.50  
Balance outstanding at the end of period (in dollars per share) 0.44 $ 0.44
Maximum    
Weighted Average Exercise Price Per Share    
Balance outstanding at the beginning of period (in dollars per share) 9.12  
Granted (in dollars per share) 2.40  
Exercised (in dollars per share) 1.20  
Forfeited (in dollars per share) 7.91  
Balance outstanding at the end of period (in dollars per share) $ 9.12 $ 9.12