XML 84 R42.htm IDEA: XBRL DOCUMENT v2.4.0.8
Fair Value Measurement of Assets and Liabilities - Estimated Fair Values of Short-Term and Long-Term Investments (Detail) (USD $)
Jun. 30, 2013
Dec. 31, 2012
Fair Value Disclosures [Abstract]    
One year or less $ 37,286,487  
One year to two years 24,218,350  
Two years to three years 18,575,315  
Three years to four years 9,471,002  
Four years to five years 5,435,462  
More than five years 1,737,456  
Estimated Fair Value $ 96,724,072 $ 115,304,625