Fair Value of Financial Instruments - Summary of Company's Financial Assets Carried at Fair Value (Detail) (USD $)
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Contingent consideration liability    $ 161,000 $ 212,000
Recurring [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Contingent consideration liability    161,000  
Recurring [Member] | Money Market Funds [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash equivalents 28,210,000 49,209,000  
Recurring [Member] | Bank Deposits [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash equivalents 5,001,000 5,037,000  
Recurring [Member] | U.S. Government Agency Securities [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Short-term marketable securities - U.S. government agency securities 100,299,000 100,161,000  
Quoted Prices in Active Markets for Identical Items (Level 1) [Member] | Recurring [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Contingent consideration liability        
Quoted Prices in Active Markets for Identical Items (Level 1) [Member] | Recurring [Member] | Money Market Funds [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash equivalents 28,210,000 49,209,000  
Quoted Prices in Active Markets for Identical Items (Level 1) [Member] | Recurring [Member] | Bank Deposits [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash equivalents        
Quoted Prices in Active Markets for Identical Items (Level 1) [Member] | Recurring [Member] | U.S. Government Agency Securities [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Short-term marketable securities - U.S. government agency securities 75,288,000 90,138,000  
Significant Other Observable Inputs (Level 2) [Member] | Recurring [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Contingent consideration liability        
Significant Other Observable Inputs (Level 2) [Member] | Recurring [Member] | Money Market Funds [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash equivalents        
Significant Other Observable Inputs (Level 2) [Member] | Recurring [Member] | Bank Deposits [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash equivalents 5,001,000 5,037,000  
Significant Other Observable Inputs (Level 2) [Member] | Recurring [Member] | U.S. Government Agency Securities [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Short-term marketable securities - U.S. government agency securities 25,011,000 10,023,000  
Significant Unobservable Inputs (Level 3) [Member] | Recurring [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Contingent consideration liability    161,000  
Significant Unobservable Inputs (Level 3) [Member] | Recurring [Member] | Money Market Funds [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash equivalents        
Significant Unobservable Inputs (Level 3) [Member] | Recurring [Member] | Bank Deposits [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Cash equivalents        
Significant Unobservable Inputs (Level 3) [Member] | Recurring [Member] | U.S. Government Agency Securities [Member]
     
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Short-term marketable securities - U.S. government agency securities