Sale-Leaseback Transaction (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013
Sale-Leaseback Transactions [Abstract]
Proceeds from sale-leaseback transactions	$ 328	$ 156

The gross proceeds received from the asset(s) sold in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller less the costs incurred in connection with the transaction, such as closing and deferred financing costs.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 40

-Section 55

-Paragraph 51

-URI http://asc.fasb.org/extlink&oid=28365400&loc=d3e51840-112757

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 40

-Section 55

-Paragraph 52

-URI http://asc.fasb.org/extlink&oid=28365400&loc=d3e51843-112757

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 40

-Section 55

-Paragraph 50

-URI http://asc.fasb.org/extlink&oid=28365400&loc=d3e51831-112757

Name:	us-gaap_SaleLeasebackTransactionNetProceeds
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration