Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Schedule of fair value, assets and liabilities measured on recurring basis

Financial assets and liabilities recognized at fair value in our condensed consolidated balance sheets by level within the fair value hierarchy were as follows (in millions):

	June 30, 2015
	Level 1		Level 2		Level 3		Netting and Collateral (a)			Total
Assets:
Commodity Futures Contracts	$	375	$	13	$	—	$	(327	)	$	61
Commodity OTC Swap Contracts	—		3		—		—			3
Commodity Forward Contracts	—		1		—		—			1
Total Assets	$	375	$	17	$	—	$	(327	)	$	65
Liabilities:
Commodity Futures Contracts	$	391	$	12	$	—	$	(386	)	$	17
Commodity OTC Swap Contracts	—		1		—		—			1
Commodity Forward Contracts	—		1		—		—			1
Environmental Credit Obligations	—		30		—		—			30
Total Liabilities	$	391	$	44	$	—	$	(386	)	$	49

	December 31, 2014
	Level 1		Level 2		Level 3		Netting and Collateral (a)			Total
Assets:
Commodity Futures Contracts	$	1,165	$	36	$	—	$	(1,136	)	$	65
Commodity Forward Contracts	—		3		—		—			3
Total Assets	$	1,165	$	39	$	—	$	(1,136	)	$	68
Liabilities:
Commodity Futures Contracts	$	1,011	$	14	$	—	$	(1,024	)	$	1
Commodity OTC Swap Contracts	—		1		—		—			1
Commodity Forward Contracts	—		1		—		—			1
Environmental Credit Obligations	—		20		—		—			20
Total Liabilities	$	1,011	$	36	$	—	$	(1,024	)	$	23

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(a) Certain of our derivative contracts, under master netting arrangements, include both asset and liability positions. We offset both the fair value amounts and any related cash collateral amounts recognized for multiple derivative instruments executed with the same counterparty when there is a legally enforceable right and an intention to settle net or simultaneously. As of June 30, 2015, we had provided cash collateral amounts of $59 million related to our unrealized derivative positions. At December 31, 2014, our counterparties had provided cash collateral of $112 million related to our unrealized derivative positions.