v2.4.0.6
Stock incentive plans (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2012
item
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Dec. 31, 2011
Mar. 31, 2011
Stock incentive plans            
Common stock shares reserved for issuance           5,511,288
Annual percentage increase alternative, increase in common stock reserved for issuance as a percentage of common stock outstanding     4.50%      
Annual fixed increase alternative, increase in shares of common stock reserved for issuance (in shares)     3,000,000      
Weighted average assumptions used for newly issued stock option grants            
Expected term     6 years 2 months 12 days      
Expected volatility (as a percent)     50.00%      
Risk free rate of return (as a percent)     0.95%      
Recognized stock-based compensation expense            
Total stock-based compensation $ 218 $ 1,372 $ 2,163 $ 2,275    
Decrease in stock-based compensation expense 1,154          
Reversal of stock-based compensation expense for unvested options 650          
Number of senior executives left, for which stock-based compensation expense reversed 2          
Number of Options            
Outstanding at the beginning of the period (in shares)     6,601,000      
Granted (in shares)     1,104,000      
Exercised (in shares)     (1,578,000)      
Cancelled/forfeited (in shares)     (743,000)      
Outstanding at the end of the period (in shares) 5,384,000   5,384,000   6,601,000  
Vested and expected to vest at the end of the period (in shares) 5,273,000   5,273,000      
Exercisable at the end of the period (in shares) 2,881,000   2,881,000      
Weighted Average Exercise Price            
Outstanding at the beginning of the period (in dollars per share)     $ 5.50      
Granted (in dollars per share)     $ 8.30      
Exercised (in dollars per share)     $ 1.35      
Cancelled/forfeited (in dollars per share)     $ 11.59      
Outstanding at the end of the period (in dollars per share) $ 6.45   $ 6.45   $ 5.50  
Vested and expected to vest at the end of the period (in dollars per share) $ 6.31   $ 6.31      
Exercisable at the end of the period (in dollars per share) $ 2.69   $ 2.69      
Weighted-Average Remaining Contract Life (years)            
Outstanding at the beginning of the period     6 years 9 months 25 days   7 years  
Outstanding at the end of the period     6 years 9 months 25 days   7 years  
Vested and expected to vest at the end of the period     6 years 9 months 11 days      
Exercisable at the end of the period     5 years 1 month 2 days      
Aggregate Intrinsic Value            
Outstanding at the beginning of the period     30,996      
Outstanding at the end of the period 17,891   17,891   30,996  
Vested and expected to vest at the end of the period 17,871   17,871      
Exercisable at the end of the period 16,666   16,666      
Network operations
            
Recognized stock-based compensation expense            
Total stock-based compensation 117 186 227 297    
Development and technology
            
Recognized stock-based compensation expense            
Total stock-based compensation (253) 228 168 388    
Selling and marketing
            
Recognized stock-based compensation expense            
Total stock-based compensation (36) 264 366 438    
General and administrative
            
Recognized stock-based compensation expense            
Total stock-based compensation $ 390 $ 694 $ 1,402 $ 1,152