Equity and Noncontrolling Interests (Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Mar. 11, 2011	Dec. 31, 2010
Variable Interest Entity [Line Items]
Preferred stock of subsidiaries	$ 0			$ 698,000,000
Equity and Preferred Stock of Subsidiaries (Narrative) (Details) [Abstract]
Convertible perpetual preferred stock outstanding	0		750,000,000	750,000,000
Approximate number of shares received by convertible preferred stockholders upon conversion			57,900,000
Number of common shares received upon conversion of one preferred share			77.2295
Percentage of general partner interest owned by El Paso in EPB	2.00%
El Paso's total ownership in EPB	44.00%
Percentage of limited partner interest owned by El Paso in EPB	42.00%
Remaining Ownership interest in Southern Natural Gas Company (SNG)	40.00%
Additional Ownership Interest in Colorado Interstate	28.00%
Payment to acquire additional ownership interest	1,400,000,000
Proceeds from issuance of common stock - EPB	948,000,000
Number of common stock issued during the period - EPB	28,500,000
Borrowings under revolving credit facility - EPB	444,000,000
Issuances of noncontrolling interests (Note 12)	(948,000,000)	(956,000,000)
Net income including additional paid in capital	294,000,000
Additional Paid In Capital [Member]
Equity and Preferred Stock of Subsidiaries (Narrative) (Details) [Abstract]
Issuances of noncontrolling interests (Note 12)	338,000,000
Noncontrolling Interest [Member]
Equity and Preferred Stock of Subsidiaries (Narrative) (Details) [Abstract]
Issuances of noncontrolling interests (Note 12)	$ 610,000,000	$ 956,000,000