Other Income (Loss), Net (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Other Income (Loss), Net      
Gains on marketable securities, realized portion $ 2,903,786 $ 234,338 $ 734,904
Gains (loss) on marketable securities, unrealized portion     804,621
Foreign exchange gain (loss) 613,227 (862,383) (379,530)
Amortized discounts related to liability for exclusive rights with Baidu (52,922) (935,177) (1,882,804)
Others 393,448 512,007 (10,061)
Total other income (loss) $ 3,857,539 $ (1,051,215) $ (732,870)