XML 29 R31.htm IDEA: XBRL DOCUMENT v2.4.0.8
Fair Value Measurements of Cash Equivalents and Available-For-Sale Investment Securities (Detail) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2013
Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments, fair value disclosure $ 204,633 $ 107,598
Money market fund
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents, fair value disclosure 6,692 51,216
U.S. Treasury notes
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale investment securities, fair value disclosure   2,030
Government sponsored enterprise securities
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale investment securities, fair value disclosure 95,477 54,352
Commercial paper
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale investment securities, fair value disclosure 40,583  
Corporate debt securities
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale investment securities, fair value disclosure 61,881  
Quoted Prices in Active Markets for Identical Assets (Level 1)
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments, fair value disclosure 6,692 53,246
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market fund
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents, fair value disclosure 6,692 51,216
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury notes
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale investment securities, fair value disclosure   2,030
Significant Other Observable Inputs (Level 2)
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments, fair value disclosure 197,941 54,352
Significant Other Observable Inputs (Level 2) | Government sponsored enterprise securities
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale investment securities, fair value disclosure 95,477 54,352
Significant Other Observable Inputs (Level 2) | Commercial paper
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale investment securities, fair value disclosure 40,583  
Significant Other Observable Inputs (Level 2) | Corporate debt securities
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale investment securities, fair value disclosure $ 61,881