Fair Value Measurements, Recurring (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Assets:
Commodity derivative contracts	$ 1,210	$ 537
Investments of certain benefit plans	111	109
Total gross fair value, assets	1,321	646
Effect of Counterparty Netting	(1,182)	(505)
Effect of Cash Collateral Netting	(5)	(7)
Commodity derivative contracts, net assets	23	25
Net Carrying Value on Balance Sheet, Assets	134	134
Cash Collateral Received Not Offset	0	0
Liabilities:
Commodity derivative contracts	1,292	516
Biofuels blending obligation	77	11
Foreign currency contracts	13	8
Total gross fair value, liabilities	1,393	540
Effect of Counterparty Netting	(1,182)	(505)
Effect of Cash Collateral Netting	(109)	(6)
Commodity derivative contracts, net liabilities	1	5
Net Carrying Value on Balance Sheet, Liabilities	102	29
Cash Collateral Paid Not Offset	(159)	(76)
Physical Purchase Contracts [Member]
Liabilities:
Physical purchase contracts	11	5
Fair Value, Inputs, Level 1 [Member]
Assets:
Commodity derivative contracts	1,182	499
Investments of certain benefit plans	100	98
Total gross fair value, assets	1,282	597
Liabilities:
Commodity derivative contracts	1,260	492
Biofuels blending obligation	0	0
Foreign currency contracts	13	8
Total gross fair value, liabilities	1,273	500
Fair Value, Inputs, Level 1 [Member] | Physical Purchase Contracts [Member]
Liabilities:
Physical purchase contracts	0	0
Fair Value, Inputs, Level 2 [Member]
Assets:
Commodity derivative contracts	28	38
Investments of certain benefit plans	0	0
Total gross fair value, assets	28	38
Liabilities:
Commodity derivative contracts	32	24
Biofuels blending obligation	77	11
Foreign currency contracts	0	0
Total gross fair value, liabilities	120	40
Fair Value, Inputs, Level 2 [Member] | Physical Purchase Contracts [Member]
Liabilities:
Physical purchase contracts	11	5
Fair Value, Inputs, Level 3 [Member]
Assets:
Commodity derivative contracts	0	0
Investments of certain benefit plans	11	11
Total gross fair value, assets	11	11
Liabilities:
Commodity derivative contracts	0	0
Biofuels blending obligation	0	0
Foreign currency contracts	0	0
Total gross fair value, liabilities	0	0
Fair Value, Inputs, Level 3 [Member] | Physical Purchase Contracts [Member]
Liabilities:
Physical purchase contracts	$ 0	$ 0