Employee Retirement and Other Termination Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	$ 7	$ 1	$ 140	$ 1
McClendon Benefit Total [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	0	0	64	0
Other Benefit Total [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	1	1	14	1
Cash Salary and Bonus Costs [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	0	0	11	0
Claw-Back Bonus [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	0	0	11	0
Acceleration of Restricted Stock Awards [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	0	0	22	0
Acceleration of Performance Shares [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	0	0	13	0
Other Costs Associated with Retirement [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	0	0	7	0
VSP Program | VSP Benefit Total [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	6	0	62	0
VSP Program | Cash Salary and Bonus Costs [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	3	0	32	0
VSP Program | Acceleration of Restricted Stock Awards [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	3	0	27	0
VSP Program | Other Costs Associated with Retirement [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employee retirement and other termination benefits	$ 0	$ 0	$ 3	$ 0