Acquisitions and Divestitures (Details) (USD $)	9 Months Ended	12 Months Ended		0 Months Ended	5 Months Ended	12 Months Ended				0 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	May 24, 2012 EP Energy Global LLC	May 24, 2012 EP Energy Global LLC	Dec. 31, 2012 EP Energy Global LLC	Dec. 31, 2012 EP Energy Global LLC Oil and natural gas properties located in the Gulf of Mexico and interest in Egypt	May 24, 2012 EP Energy Global LLC Debt issue costs	May 24, 2012 EP Energy Global LLC Prepaid costs in other assets	May 24, 2012 EP Energy Global LLC Predecessor
Acquisitions
Acquisition price										$ 7,200,000,000
Equity contributions to fund acquisition	3,323,000,000			3,300,000,000
Proceeds from issuance of debt used to fund acquisition				4,250,000,000
Repayment of revolving line of credit										960,000,000
Amount of goodwill associated with acquisitions				0	0
Preliminary allocation of the adjusted purchase to specific assets and liabilities assumed
Current assets				587,000,000	587,000,000
Non-current assets				446,000,000	446,000,000
Property, plant and equipment				6,897,000,000	6,897,000,000
Current liabilities				(420,000,000)	(420,000,000)
Non-current liabilities				(297,000,000)	(297,000,000)
Total purchase price				7,213,000,000	7,213,000,000
Unaudited pro forma information
Operating Revenues		1,659,000,000	1,756,000,000
Net Income		143,000,000	454,000,000
Payment of transaction, advisory and other fees				330,000,000	330,000,000			142,000,000	15,000,000
Transaction costs reflected in general and administrative expense					173,000,000
Transition and restructuring costs						48,000,000
Severance charges						$ 17,000,000	$ 4,000,000