Quarterly report pursuant to Section 13 or 15(d)

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

v2.4.0.8
Fair Value Measurements and Marketable Securities - Summary of Company's Available-for-Sale Securities (Detail) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2014
Dec. 31, 2013
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis $ 68,735 $ 74,726
Unrealized Gain 23 38
Unrealized Loss (6) (10)
Fair Value 68,752 74,754
Money Market Funds
    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 6,463 4,285
Unrealized Gain      
Unrealized Loss      
Fair Value 6,463 4,285
Certificates of Deposit
    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 2,844 1,584
Unrealized Gain      
Unrealized Loss      
Fair Value 2,844 1,584
Corporate Debt Securities
    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 40,930 49,001
Unrealized Gain 12 25
Unrealized Loss (5) (7)
Fair Value 40,937 49,019
U. S. Government Securities
    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 20,013 21,722
Unrealized Gain 11 12
Unrealized Loss (1) (3)
Fair Value 20,023 21,731
Municipal Securities
    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 1,450 2,814
Unrealized Gain    1
Unrealized Loss      
Fair Value 1,450 2,815
Commercial Paper
    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 3,498 2,599
Unrealized Gain      
Unrealized Loss      
Fair Value 3,498 2,599
Marketable Securities Including Cash Equivalents
    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 75,198 82,005
Unrealized Gain 23 38
Unrealized Loss (6) (10)
Fair Value 75,215 82,033
Less Cash Equivalents
    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 6,463 7,279
Unrealized Gain      
Unrealized Loss      
Fair Value $ 6,463 $ 7,279