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Stock-based Compensation - Additional Information (Detail) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of options for every share issued 1.75  
Discount from fair market value on purchase date 85.00%  
Maximum number of shares per employee 2,000  
Employee stock purchase plan offering period 6 months  
Maximum value of shares per employee $ 25,000  
Common stock reserved for issuance 1,000,000  
Shares purchased by employee since inception of ESPP 519,440  
Shares purchased under ESPP 36,921 25,628
Expected dividend yield in option-pricing model 0.00%  
Unrecognized compensation cost $ 6,800,000  
Stock Options [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based payment award vesting period (years) 4 years  
Unrecognized compensation cost, recognized over an estimated weighted-average period (years) 3 years 3 months 22 days  
Stock Options [Member] | Maximum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based payment award expiration period (years) 10 years  
Stock Options [Member] | Minimum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based payment award expiration period (years) 5 years  
Restricted Stock Awards [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based payment award vesting period (years) 1 year  
Unrecognized compensation cost, recognized over an estimated weighted-average period (years) 1 year 6 months 26 days  
Restricted Stock Units [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based payment award vesting period (years) 3 years  
Unrecognized compensation cost, recognized over an estimated weighted-average period (years) 5 months 5 days