Equity Compensation (Details 2) (Stock Options, USD $)
6 Months Ended
Jun. 30, 2014
Options Outstanding  
Number of Underlying Shares 4,697,807
Options Exercisable  
Number of Underlying Shares 2,694,980
$0.52-1.72
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 0.52
Range of Exercise Price, high end of range (in dollars per share) $ 1.72
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 0.98
Number of Underlying Shares 52,971
Weighted-Average Remaining Contractual Life 1 year 2 months 12 days
Options Exercisable  
Number of Underlying Shares 52,971
Weighted-Average Remaining Contractual Life 1 year 2 months 12 days
$1.97-3.38
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 1.97
Range of Exercise Price, high end of range (in dollars per share) $ 3.38
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 2.43
Number of Underlying Shares 410,623
Weighted-Average Remaining Contractual Life 1 year 10 months 24 days
Options Exercisable  
Number of Underlying Shares 410,623
Weighted-Average Remaining Contractual Life 1 year 10 months 24 days
$3.58-6.14
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 3.58
Range of Exercise Price, high end of range (in dollars per share) $ 6.14
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 5.54
Number of Underlying Shares 1,897,260
Weighted-Average Remaining Contractual Life 5 years 6 months
Options Exercisable  
Number of Underlying Shares 1,600,058
Weighted-Average Remaining Contractual Life 5 years 2 months 12 days
$6.34-9.94
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 6.34
Range of Exercise Price, high end of range (in dollars per share) $ 9.94
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 8.27
Number of Underlying Shares 1,062,937
Weighted-Average Remaining Contractual Life 7 years 9 months 18 days
Options Exercisable  
Number of Underlying Shares 527,829
Weighted-Average Remaining Contractual Life 7 years 7 months 6 days
$11.28-16.97
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 11.28
Range of Exercise Price, high end of range (in dollars per share) $ 16.97
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 11.99
Number of Underlying Shares 442,984
Weighted-Average Remaining Contractual Life 7 years 10 months 24 days
Options Exercisable  
Number of Underlying Shares 101,799
Weighted-Average Remaining Contractual Life 6 years 7 months 6 days
$17.66-22.92
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 17.66
Range of Exercise Price, high end of range (in dollars per share) $ 22.92
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 21.01
Number of Underlying Shares 831,032
Weighted-Average Remaining Contractual Life 9 years 7 months 6 days
Options Exercisable  
Number of Underlying Shares 1,700
Weighted-Average Remaining Contractual Life 9 years 1 month 6 days