Short-Term and Long-Term Investments - Summary of Marketable Securities (Detail) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2014
Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 29,742 $ 25,771
Gross Unrealized Gains 5 3
Gross Unrealized Losses (11) (3)
Fair Value 29,736 25,771
Certificates of Deposit [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 9,923 1,784
Gross Unrealized Gains 1  
Gross Unrealized Losses (11) (1)
Fair Value 9,913 1,783
U.S. Government Agency Notes [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 19,819 23,987
Gross Unrealized Gains 4 3
Gross Unrealized Losses   (2)
Fair Value $ 19,823 $ 23,988