Principal Accounting Policies (Intangible assets, net) (Details)	12 Months Ended
Dec. 31, 2012
Computer software [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	5 years
Internet domain name [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	10 years

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration