Intangible Assets, Net (Details) (USD $)
12 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Mar. 31, 2014
Intangible Assets, Net          
Intangible assets subject to amortization, gross $ 276,762,319 $ 273,109,420      
Intangible assets subject to amortization, net 119,599,586 140,449,143      
Total intangible assets, net 120,380,671 141,231,750      
Weighted Average Amortization Periods 9 years 6 months 18 days        
Amortization amount 52,922 935,177 1,882,804    
Amortization expense 24,677,508 37,009,330 38,701,651    
Amortization expense expected to be recorded          
2015 16,648,450        
2016 14,183,003        
2017 13,932,242        
2018 12,813,362        
2019 11,936,725        
Advertising agency agreement with SINA          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 106,790,000 106,790,000      
Less: Accumulated amortization (51,286,533) (44,495,832)      
Weighted Average Amortization Periods 9 years 9 months        
License agreements with SINA          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 80,660,000 80,660,000      
Less: Accumulated amortization (39,377,764) (34,280,500)      
Weighted Average Amortization Periods 9 years 9 months        
Exclusive rights with Baidu          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 45,151,494 45,315,329      
Less: Accumulated amortization (43,034,803) (34,693,471)      
Weighted Average Amortization Periods 3 months        
Purchase price of intangible assets       47,612,100  
Fair value of intangible assets       43,847,992  
Difference between fair value and principal amount       3,764,108  
Payment to acquire exclusive rights 9,004,710 15,347,915 14,249,180    
Amortization amount 52,922 935,177 1,882,804    
Customer relationship          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 12,084,676 12,100,847      
Less: Accumulated amortization (8,086,039) (6,464,705)      
Weighted Average Amortization Periods 5 years 1 month 17 days        
Database Rights [Member]          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 8,300,000 8,300,000      
Less: Accumulated amortization (5,126,472) (4,150,001)      
Weighted Average Amortization Periods 3 years 3 months        
Favorable lease term          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 9,541,891 9,541,891      
Less: Accumulated amortization (1,167,905) (637,435)      
Weighted Average Amortization Periods 16 years 11 months 12 days        
Computer software licenses          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 9,534,433 5,708,188      
Less: Accumulated amortization (4,784,950) (3,963,457)      
Weighted Average Amortization Periods 4 years 10 months 17 days        
Non-compete agreements          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 3,415,152 3,420,712      
Less: Accumulated amortization (3,349,230) (3,097,470)      
Weighted Average Amortization Periods 9 months        
Customer contracts          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 1,054,964 1,057,842      
Less: Accumulated amortization (871,174) (832,950)      
Weighted Average Amortization Periods 4 years 11 months 9 days        
Domain name          
Intangible Assets, Net          
Intangible assets subject to amortization, gross 229,709 214,611      
Less: Accumulated amortization (77,863) (44,456)      
Weighted Average Amortization Periods 4 years 8 months 5 days        
SINA | Advertising agency agreement and license agreements          
Intangible Assets, Net          
Additional extension of agreement period         5 years
Percentage of revenue fee on sales         15.00%
Trademark          
Intangible Assets, Net          
Intangible assets not subject to amortization $ 781,085 $ 782,607