Contingent Liabilities (Details Textual) (USD $) In Millions	84 Months Ended								1 Months Ended
	Dec. 31, 2010	Sep. 30, 2011	Sep. 30, 2011 Former Operations	Sep. 30, 2011 Natural gas underground storage facilities	Dec. 31, 2008 Gulf Liquids	Dec. 31, 2006 Gulf Liquids	Jan. 28, 2008 Gulf Liquids Gulsby-Bay	Jan. 28, 2008 Gulf Liquids Gulsby	Feb. 28, 2011 Pending or Threatened Litigation	Sep. 30, 2011 Gas Pipeline
Contingent Liabilities (Textuals) [Abstract]
Accrued environmental loss liabilities		$ 47	$ 28	$ 8						$ 11
Estimated exposure for actual damages						68
Potential interest in addition to actual damages						20
Possible ultimate judgement in excess of accrual						199
Litigation award against Gulf Liquids, Damages							4	11
Loss contingency accrual reduction					43
Loss contingency accrued interest reduction					11
Assertion of Counterclaim									200
Contingent Liabilities Additional (Textuals) [Abstract]
Deductions used in calculation of royalty payments.	$ 55