Stock-Based Compensation - Narrative (Details) (USD $)
12 Months Ended 12 Months Ended 12 Months Ended
Dec. 31, 2013
Oct. 26, 2011
Dec. 31, 2013
Stock options
Dec. 31, 2012
Stock options
Dec. 31, 2013
RSUs
Dec. 31, 2012
RSUs
Dec. 31, 2013
Less than 10%
Dec. 31, 2013
More than 10%
Dec. 31, 2013
Annual vesting period
Stock-based compensation                  
Number of shares reserved for issuance   4,225,648              
Provision for number of additional shares authorized, maximum shares 2,535,389                
Provision for number of additional shares authorized, percent 4.50%                
Additional shares issued 1,982,113                
Voting power maximum percent 10.00%                
Exercise price fair market value percentage             100.00% 110.00%  
Voting power minimum percent 10.00%                
Vesting rights percentage                 25.00%
Maximum term from date of grant 10 years             5 years  
Weighted average grant date fair value (in usd per share)     $ 4.16 $ 4.50          
Vesting period         4 years        
Aggregate intrinsic value         $ 4,200,000 $ 2,300,000      
Unrecognized compensation 7,298,000                
Unrecognized compensation weighted average period     2 years 8 months 12 days   2 years 10 months 24 days        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value $ 500,000