Annual report pursuant to Section 13 and 15(d)

Stock Incentive Plan - Narrative (Details)

v3.6.0.2
Stock Incentive Plan - Narrative (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2011
Dec. 31, 2013
Dec. 31, 2010
May 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Granted (in shares) 665,000 747,100 145,000        
Total intrinsic value of options exercised $ 575 $ 1,024 $ 2,030        
Exercise of stock options, net (in shares) 320,892 332,600 482,475        
Exercised (in usd per share) $ 3.286 $ 3.467 $ 2.999        
Proceeds from exercises of options $ 1,054 $ 1,153 $ 1,447        
Weighted average exercise price (in usd per share) $ 7.300 $ 7.740 $ 7.721   $ 7.528    
Stock-based compensation expense $ 1,462 $ 1,769 $ 2,493        
Stock Options              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Options vesting period       5 years      
Ratable vesting percentage 33.33%     20.00%      
Exercise term upon termination 90 days            
Weighted average exercise price (in usd per share) $ 2.60 $ 3.03 $ 3.97        
Non-vested stock options unrecognized compensation expense $ 2,990            
Non-vested stock options unrecognized compensation expense, weighted-average period of recognition 2 years 8 months 12 days            
Stock Options | Minimum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Options vesting period 3 years            
Stock Options | Maximum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Options vesting period 5 years            
Stock Options | Tranche One              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Ratable vesting percentage 20.00%            
Stock Options | Tranche Two              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Ratable vesting percentage 5.00%            
Class A Common Stock              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Common stock, par value (in dollars per share) $ 0.0001 $ 0.0001          
2000 Plan              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares reserved for future issuance           28,500,000  
Common stock, par value (in dollars per share)           $ 0.0001  
2000 Plan | Stock Options | Maximum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Options vesting period 10 years            
2010 Plan | Stock Options              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares available for grant (in shares) 7,409,802            
Options vesting period 10 years            
2010 Plan | Class A Common Stock              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares reserved for future issuance             10,000,000
Granted (in shares) 3,119,604