Fair Value Measurements Unobservable Input Or Level 3 Table and Footnote (Details) (USD $) In Millions, unless otherwise specified		6 Months Ended				3 Months Ended	6 Months Ended					3 Months Ended	6 Months Ended
	Jun. 30, 2012 Interest rate contract	Jun. 30, 2013 Fair Value, Inputs, Level 3 [Member] Natural Gas, Oil and NGL sales	Jun. 30, 2012 Fair Value, Inputs, Level 3 [Member] Natural Gas, Oil and NGL sales	Jun. 30, 2013 Fair Value, Inputs, Level 3 [Member] Interest Expense	Jun. 30, 2012 Fair Value, Inputs, Level 3 [Member] Interest Expense	Jun. 29, 2013 Fair Value, Inputs, Level 3 [Member] Commodity contracts	Jun. 29, 2012 Fair Value, Inputs, Level 3 [Member] Commodity contracts	Jun. 30, 2013 Fair Value, Inputs, Level 3 [Member] Commodity contracts	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Commodity contracts	Jun. 30, 2012 Fair Value, Inputs, Level 3 [Member] Commodity contracts	Dec. 31, 2011 Fair Value, Inputs, Level 3 [Member] Commodity contracts	Jun. 29, 2013 Fair Value, Inputs, Level 3 [Member] Interest rate contract	Jun. 29, 2012 Fair Value, Inputs, Level 3 [Member] Interest rate contract	Jun. 30, 2013 Fair Value, Inputs, Level 3 [Member] Interest rate contract	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Interest rate contract	Dec. 31, 2011 Fair Value, Inputs, Level 3 [Member] Interest rate contract
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 0							$ (594)	$ (1,016)	$ (1,064)	$ (1,654)			$ 0	$ 0	$ 0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings Or Change In Net Assets Unrealized		362	548	(1)	2	362	548					(1)	2
Sales						0	0					1	(2)
Settlements						60	42					0	0
Ending balance	0							(594)	(1,016)	(1,064)	(1,654)			0	0	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		$ 353	$ 430	$ 0	$ 0