Principal Accounting Policies (Property and equipment, net) (Details)	12 Months Ended
	Dec. 31, 2014
Computer, equipment and furniture [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Motor vehicles [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	Lesser of lease terms or the estimated useful lives of the assets