Share-Based Compensation - Total Stock-Based Compensation Expense (Detail) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total share-based compensation expense $ 391,393 $ 295,106
Research and Development [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total share-based compensation expense 132,543 111,206
General and Administrative [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Total share-based compensation expense $ 258,850 $ 183,900