Acquisitions and Dispositions Acquisitions and Dispositions (Details) (USD $) In Millions, unless otherwise specified	May 01, 2013
Business Combinations [Abstract]
Sale proceeds from disposal of properties	$ 5.8
Reduction of asset retirement obligation due to sale of properties	$ 11.3

The value of all consideration given or received by the Entity in the significant acquisition or disposal.

No definition available.

Name:	us-gaap_SignificantAcquisitionsAndDisposalsAcquisitionCostsOrSaleProceeds
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant