Asset Retirement Obligations (Details Textuals) (USD $) In Millions	3 Months Ended	9 Months Ended
Jun. 30, 2011	Mar. 31, 2011	Sep. 30, 2011
Asset Retirement Obligations [Line Items]
Asset Retirement Obligation, Revision of Estimate		$ 19	$ (1)
Asset Retirement Obligation, Period Increase (Decrease)	20
Reserve and Impairment of Retirement Obligation	$ 6

Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 22

-Subparagraph c(4)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)(4)

-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Name:	us-gaap_AssetRetirementObligationRevisionOfEstimate
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration