Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2012

Fair Value Measurements

Assets and liabilities measured at fair value on a recurring basis (in millions)

	Fair Value Measurements at September 30, 2012 Using
Description	Level 1		Level 2		Level 3		Netting and Collateral (a)			Total Fair Value
Assets:
Commodity derivatives	$	151	$	438	$	—	$	(432	)	$	157
Liabilities:
Commodity derivatives	$	138	$	518	$	—	$	(515	)	$	141

	Fair Value Measurements at December 31, 2011 Using
Description	Level 1		Level 2		Level 3		Netting and Collateral (a)			Total Fair Value
Assets:
Commodity derivatives	$	310	$	640	$	—	$	(758	)	$	192
Liabilities:
Commodity derivatives	$	311	$	652	$	—	$	(782	)	$	181

(a)Represents the impact of netting assets, liabilities and collateral when a legal right of offset exists.