Immaterial Corrections - Additional Information (Detail) (Adjustments [Member], USD $)	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2011
Adjustments [Member]
Basic and diluted earnings per share	$ 0.33	$ 0.32
Basic and diluted earnings per share related to discontinued operations	$ 0.20	$ 0.20

The amount of income (loss) derived from discontinued operations during the period, net of related tax effect, per each basic and diluted share of common stock or unit when the per share amount is the same for both basic and diluted shares.

No definition available.

Name:	us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicAndDilutedShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration