Segment Information - Additional information (Detail)	6 Months Ended
Jun. 30, 2012 Segment
Segment Reporting Information [Line Items]
Number of reportable segments	3
Retail
Segment Reporting Information [Line Items]
Percentage of ownership in joint venture	51.00%

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration