Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements and Marketable Securities - Summary of Company's Available-for-Sale Securities (Detail)

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Fair Value Measurements and Marketable Securities - Summary of Company's Available-for-Sale Securities (Detail) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]    
Cost Basis $ 74,726 $ 59,808
Unrealized Gain 38 18
Unrealized Loss (10) (7)
Fair Value 74,754 59,819
Money market funds [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Cost Basis 4,285 5,886
Unrealized Gain      
Unrealized Loss      
Fair Value 4,285 5,886
Certificates of deposit [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Cost Basis 1,584 1,185
Unrealized Gain      
Unrealized Loss      
Fair Value 1,584 1,185
Corporate debt securities [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Cost Basis 49,001 20,237
Unrealized Gain 25 6
Unrealized Loss (7) (1)
Fair Value 49,019 20,242
Government securities [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Cost Basis 21,722 27,893
Unrealized Gain 12 12
Unrealized Loss (3) (6)
Fair Value 21,731 27,899
Municipal securities [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Cost Basis 2,814  
Unrealized Gain 1  
Unrealized Loss     
Fair Value 2,815  
Commercial paper [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Cost Basis 2,599 15,613
Unrealized Gain      
Unrealized Loss      
Fair Value 2,599 15,613
Marketable securities including cash equivalents [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Cost Basis 82,005 70,814
Unrealized Gain 38 18
Unrealized Loss (10) (7)
Fair Value 82,033 70,825
Less cash equivalents [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Cost Basis 7,279 11,006
Unrealized Gain      
Unrealized Loss      
Fair Value $ 7,279 $ 11,006