Fair Value Measurements (Details) (Ongoing basis, USD $)
In Thousands, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Total
    
Assets:    
Fair value of assets $ 14,172 $ 16,109
Liabilities:    
Fair value of liabilities   1,750
Total | Contingent consideration
    
Liabilities:    
Fair value of liabilities   1,750 [1]
Total | Money market funds
    
Assets:    
Fair value of assets 6,306 [2] 3,338 [2]
Total | U.S. Treasury bills
    
Assets:    
Fair value of assets   1,000 [3]
Total | Corporate notes and obligations
    
Assets:    
Fair value of assets 6,115 [3] 6,071 [3]
Total | U.S. government and agency obligations
    
Assets:    
Fair value of assets 1,751 [3] 5,700 [3]
Quoted Prices in Active Markets for Identical Assets (Level 1)
    
Assets:    
Fair value of assets 6,306 4,338
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
    
Assets:    
Fair value of assets 6,306 [2] 3,338 [2]
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury bills
    
Assets:    
Fair value of assets   1,000 [3]
Significant Other Observable Inputs (Level 2)
    
Assets:    
Fair value of assets 7,866 11,771
Significant Other Observable Inputs (Level 2) | Corporate notes and obligations
    
Assets:    
Fair value of assets 6,115 [3] 6,071 [3]
Significant Other Observable Inputs (Level 2) | U.S. government and agency obligations
    
Assets:    
Fair value of assets 1,751 [3] 5,700 [3]
Significant Unobservable Inputs (Level 3)
    
Liabilities:    
Fair value of liabilities   1,750
Significant Unobservable Inputs (Level 3) | Contingent consideration
    
Liabilities:    
Fair value of liabilities   $ 1,750 [1]
[1] Included in accrued expenses on the consolidated balance sheet.
[2] Included in cash and cash equivalents on the consolidated balance sheet.
[3] Included in short-term investments on the consolidated balance sheet.