Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation - Additional Information (Detail)

v2.4.0.8
Stock Based Compensation - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation expense $ 1,266,000 $ 1,053,000
Non-employee stock-based compensation expense 36,000 35,000
Total intrinsic value of stock options exercised 100,000 100,000
Cash received from stock option exercises 55,000 33,000
Amount withheld by plan participants to purchase stock 100,000  
Employee Stock-Based Compensation Expense [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation expense 1,200,000 1,000,000
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans $ 9,800,000  
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans, period for recognition 2 years 3 months 18 days  
2004 Equity Incentive Plan [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Additional shares authorized for issuance 1,250,000  
Shares authorized and available for issuance 1,256,173  
2004 Employee Stock Purchase Plan [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Additional shares authorized for issuance 100,000  
Shares authorized and available for issuance 261,834  
Plan participants purchased shares 74,062  
Average purchase price under 2004 Employee Stock Purchase Plan $ 3.91