Assets and Liabilities with Recurring Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 896	[1]	$ 1,134	[1]
Margin Deposit Assets	96	[2]	261	[2]
Commodity futures contracts	2,134		434
Commodity forward contracts	359	[3]	107	[3]
Interest rate swaps	4		9
Total assets	3,489		1,945
Security Deposit Liability	47	[2],[4]	5	[2],[4]
Commodity futures contracts	1,870		495
Commodity forward contracts	242	[3]	70	[3]
Interest rate swaps	114		129
Total liabilities	2,273		699
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	896	[1]	1,134	[1]
Margin Deposit Assets	96		261
Commodity futures contracts	2,134		434
Commodity forward contracts	0	[3]	0	[3]
Interest rate swaps	0		0
Total assets	3,126		1,829
Security Deposit Liability	47		5
Commodity futures contracts	1,870		495
Commodity forward contracts	0	[3]	0	[3]
Interest rate swaps	0		0
Total liabilities	1,917		500
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	[1]	0	[1]
Margin Deposit Assets	0		0
Commodity futures contracts	0		0
Commodity forward contracts	195	[3]	75	[3]
Interest rate swaps	4		9
Total assets	199		84
Security Deposit Liability	0		0
Commodity futures contracts	0		0
Commodity forward contracts	163	[3]	52	[3]
Interest rate swaps	114		129
Total liabilities	277		181
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	[1]	0	[1]
Margin Deposit Assets	0		0
Commodity futures contracts	0		0
Commodity forward contracts	164	[3]	32	[3]
Interest rate swaps	0		0
Total assets	164		32
Security Deposit Liability	0		0
Commodity futures contracts	0		0
Commodity forward contracts	79	[3]	18	[3]
Interest rate swaps	0		0
Total liabilities	$ 79		$ 18

[1] As of December 31, 2014 and 2013, we had cash equivalents of $679 million and $889 million included in cash and cash equivalents and $217 million and $245 million included in restricted cash, respectively.

[2] Balances are subject to master netting arrangements and presented on a gross basis on our Consolidated Balance Sheets. We do not offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation, and we do not offset amounts recognized for the right to reclaim, or the obligation to return, cash collateral with corresponding derivative instrument fair values. See Note 8 for further discussion of our derivative instruments subject to master netting arrangements.

[3] Includes OTC swaps and options.

[4] Included in other current liabilities on our Consolidated Balance Sheets.