Equity Compensation (Details 2) (Stock Options, USD $)
3 Months Ended
Mar. 31, 2014
Options Outstanding  
Number of Underlying Shares 4,894,474
Options Exercisable  
Number of Underlying Shares 2,668,667
0.26-1.30
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 0.26
Range of Exercise Price, high end of range (in dollars per share) $ 1.30
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 0.64
Number of Underlying Shares 63,440
Weighted-Average Remaining Contractual Life 1 year
Options Exercisable  
Number of Underlying Shares 63,440
Weighted-Average Remaining Contractual Life 1 year
1.35-2.60
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 1.35
Range of Exercise Price, high end of range (in dollars per share) $ 2.60
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 2.22
Number of Underlying Shares 299,241
Weighted-Average Remaining Contractual Life 1 year 9 months 18 days
Options Exercisable  
Number of Underlying Shares 299,241
Weighted-Average Remaining Contractual Life 1 year 9 months 18 days
2.65-3.90
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 2.65
Range of Exercise Price, high end of range (in dollars per share) $ 3.90
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 3.17
Number of Underlying Shares 252,213
Weighted-Average Remaining Contractual Life 2 years 7 months 6 days
Options Exercisable  
Number of Underlying Shares 252,213
Weighted-Average Remaining Contractual Life 2 years 7 months 6 days
3.95-5.20
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 3.95
Range of Exercise Price, high end of range (in dollars per share) $ 5.20
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 4.87
Number of Underlying Shares 765,480
Weighted-Average Remaining Contractual Life 3 years 10 months 24 days
Options Exercisable  
Number of Underlying Shares 765,480
Weighted-Average Remaining Contractual Life 3 years 10 months 24 days
5.25-6.50
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 5.25
Range of Exercise Price, high end of range (in dollars per share) $ 6.50
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 6.18
Number of Underlying Shares 1,510,915
Weighted-Average Remaining Contractual Life 7 years 1 month 6 days
Options Exercisable  
Number of Underlying Shares 960,056
Weighted-Average Remaining Contractual Life 6 years 10 months 24 days
6.55-7.80
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 6.55
Range of Exercise Price, high end of range (in dollars per share) $ 7.80
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 7.49
Number of Underlying Shares 108,979
Weighted-Average Remaining Contractual Life 6 years 3 months 18 days
Options Exercisable  
Number of Underlying Shares 96,014
Weighted-Average Remaining Contractual Life 6 years 3 months 18 days
7.85-9.10
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 7.85
Range of Exercise Price, high end of range (in dollars per share) $ 9.10
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 8.84
Number of Underlying Shares 230,734
Weighted-Average Remaining Contractual Life 8 years 2 months 12 days
Options Exercisable  
Number of Underlying Shares 101,721
Weighted-Average Remaining Contractual Life 8 years 2 months 12 days
9.15-22.92
 
Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)  
Range of Exercise Price, low end of range (in dollars per share) $ 9.15
Range of Exercise Price, high end of range (in dollars per share) $ 22.92
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 15.89
Number of Underlying Shares 1,663,472
Weighted-Average Remaining Contractual Life 9 years 1 month 6 days
Options Exercisable  
Number of Underlying Shares 130,502
Weighted-Average Remaining Contractual Life 8 years 8 months 12 days