Summary of Principal Accounting Policies (Details 5)
12 Months Ended
Dec. 31, 2014
Buildings  
Property and equipment, net  
Estimated useful life 30 years
Motor vehicles  
Property and equipment, net  
Estimated useful life 5 years
Minimum | Furniture, fixtures and equipment  
Property and equipment, net  
Estimated useful life 3 years
Maximum | Furniture, fixtures and equipment  
Property and equipment, net  
Estimated useful life 5 years