Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2013

Fair Value Measurements

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

	Fair Value Measurements at
	September 30, 2013 Using
							Netting and			Total Fair
Description	Level 1		Level 2		Level 3		Collateral		(a)	Value
Assets:
Commodity derivatives	$	551	$	314	$	—	$	(750	)	$	115
Liabilities:
Commodity derivatives	$	524	$	344	$	—	$	(784	)	$	84

	Fair Value Measurements at
	December 31, 2012 Using
							Netting and			Total Fair
Description	Level 1		Level 2		Level 3		Collateral		(a)	Value
Assets:
Commodity derivatives	$	107	$	312	$	—	$	(301	)	$	118
Liabilities:
Commodity derivatives	$	99	$	398	$	—	$	(371	)	$	126

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