Reclassifications Additional Information (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012
Reclassifications [Line Items]
Increase in total assets and liabilities due to prior period reclassification adjustment	$ 57.9

The amount of a reclassification adjustment made to prior period financial statement amounts.

No definition available.

Name:	us-gaap_PriorPeriodReclassificationAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration