Summary of Significant Accounting Policies - Share Split (Details) (Parent Company [Member])	12 Months Ended
Dec. 31, 2011
Parent Company [Member]
Entity Information [Line Items]
Stockholders' Equity Note, Stock Split, Conversion Ratio	2

This item represents the conversion ratio used in the calculation of a stock split.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Stock Split

-URI http://asc.fasb.org/extlink&oid=6525746

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 4

-Subparagraph (SAB TOPIC 4.C)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187143-122770

Name:	us-gaap_StockholdersEquityNoteStockSplitConversionRatio
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration