Short-Term and Long-Term Investments - Additional Information (Detail) (USD $)
3 Months Ended 6 Months Ended
Jun. 30, 2014
Jun. 30, 2013
Jun. 30, 2014
Jun. 30, 2013
Schedule of Available-for-sale Securities [Line Items]        
Marketable securities maturity period     1 year  
Realized gains or losses on short-term investments $ 10,000 $ 0 $ 10,000 $ 0
Other-than-temporary impairments recognized 0 0 0 0
Certificates of Deposit [Member]
       
Schedule of Available-for-sale Securities [Line Items]        
Certificates of deposit $ 250,000   $ 250,000