Redeemable Convertible Preferred Stock and Stockholders' Deficit (Details 4) (Stock Options, USD $)
9 Months Ended
Sep. 30, 2013
Options Outstanding  
Number of Underlying Shares 4,949,565
Options Exercisable  
Number of Underlying Shares 3,061,051
0.26-1.30
 
Redeemable Convertible Preferred Stock and Stockholders' 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) $ 0.56
Number of Underlying Shares 190,939
Weighted-Average Remaining Contractual Life 1 year 2 months 12 days
Options Exercisable  
Number of Underlying Shares 190,939
Weighted-Average Remaining Contractual Life 1 year 2 months 12 days
1.35-2.60
 
Redeemable Convertible Preferred Stock and Stockholders' 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) $ 2.18
Number of Underlying Shares 473,347
Weighted-Average Remaining Contractual Life 2 years 8 months 12 days
Options Exercisable  
Number of Underlying Shares 473,347
Weighted-Average Remaining Contractual Life 2 years 8 months 12 days
2.65-3.90
 
Redeemable Convertible Preferred Stock and Stockholders' 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) $ 3.23
Number of Underlying Shares 325,523
Weighted-Average Remaining Contractual Life 3 years 9 months 18 days
Options Exercisable  
Number of Underlying Shares 325,523
Weighted-Average Remaining Contractual Life 3 years 9 months 18 days
3.95-5.20
 
Redeemable Convertible Preferred Stock and Stockholders' 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 954,522
Weighted-Average Remaining Contractual Life 5 years 6 months
Options Exercisable  
Number of Underlying Shares 926,448
Weighted-Average Remaining Contractual Life 5 years 6 months
5.25-6.50
 
Redeemable Convertible Preferred Stock and Stockholders' 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) $ 6.19
Number of Underlying Shares 1,734,885
Weighted-Average Remaining Contractual Life 8 years
Options Exercisable  
Number of Underlying Shares 933,316
Weighted-Average Remaining Contractual Life 7 years 10 months 24 days
6.55-7.80
 
Redeemable Convertible Preferred Stock and Stockholders' 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 118,947
Weighted-Average Remaining Contractual Life 6 years 9 months 18 days
Options Exercisable  
Number of Underlying Shares 95,260
Weighted-Average Remaining Contractual Life 6 years 9 months 18 days
7.85-9.10
 
Redeemable Convertible Preferred Stock and Stockholders' 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 239,893
Weighted-Average Remaining Contractual Life 8 years 8 months 12 days
Options Exercisable  
Number of Underlying Shares 81,075
Weighted-Average Remaining Contractual Life 8 years 8 months 12 days
9.15-22.77
 
Redeemable Convertible Preferred Stock and Stockholders' 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) $ 22.77
Options Outstanding  
Weighted Average Exercise Price (in dollars per share) $ 11.40
Number of Underlying Shares 911,509
Weighted-Average Remaining Contractual Life 8 years 10 months 24 days
Options Exercisable  
Number of Underlying Shares 35,143
Weighted-Average Remaining Contractual Life 9 years 1 month 6 days