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Short-Term and Long-Term Investments - Additional Information (Detail) (USD $)
 12 Months Ended 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2013
Failed Auction Securities [Member]
Dec. 31, 2012
Failed Auction Securities [Member]
Dec. 31, 2013
Failed Auction Securities [Member]
Minimum [Member]
Dec. 31, 2013
Failed Auction Securities [Member]
Maximum [Member]
Unrealized Losses On Short Term And Long Term Investments [Line Items]                
Auction rate securities, par value $ 6,820,000 $ 7,845,000     $ 6,000,000 $ 6,100,000    
Interest rates auction time             7 days 28 days
Period for which Failed Auction Securities been in unrealized loss position         Exceeds 12 months      
Minimum Period for which failed Auction Securities been in unrealized loss position 12 months              
Fair value of Failed Auction Securities 5,651,000 6,736,000     4,825,000 4,979,000    
Decrease in fair value           54,000    
Redemption, net           100,000    
Gross Unrealized Losses 1,175,000 1,121,000     1,175,000 1,121,000    
Aggregate credit loss 395,000 317,000 308,000 610,000 395,000      
Aggregate temporary impairment loss         780,000      
Increased aggregate credit (losses) gains on Failed Auction Securities         $ 78,000