Derivative Instruments (Details 4) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Loss) Recognized in OCI (Effective Portion)	$ (81)		$ (94)
Gain (Loss) Reclassified from AOCI into Income (EffectivePortion)	20	[1]	25	[1]
Gain (Loss) Reclassified from AOCI into Income (IneffectivePortion)	2		(3)
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Loss) Recognized in OCI (Effective Portion)	(43)		(23)
Gain (Loss) Reclassified from AOCI into Income (EffectivePortion)	(32)	[1],[2]	(138)	[1],[2]
Gain (Loss) Reclassified from AOCI into Income (IneffectivePortion)	0		(1)
Commodity Option [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Loss) Recognized in OCI (Effective Portion)	(38)		(71)
Gain (Loss) Reclassified from AOCI into Income (EffectivePortion)	52	[1],[3]	163	[1],[3]
Gain (Loss) Reclassified from AOCI into Income (IneffectivePortion)	$ 2		$ (2)

[1] Cumulative cash flow hedge losses, net of tax, remaining in AOCI were $242 million and $172 million at December 31, 2012 and 2011, respectively.

[2] Reclassification of losses from OCI to earnings consisted of $32 million from the reclassification of interest rate contracts due to settlement for each of the years ended December 31, 2012 and 2011, $15 million in losses from terminated interest rate contracts due to the repayment of project debt in 2011, and $91 million in losses from existing interest rate contracts reclassified from OCI into earnings due to the refinancing of variable rate First Lien Credit Facility term loans for the year ended December 31, 2011.

[3] Included in Commodity revenue and Commodity expense on our Consolidated Statements of Operations.