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Assets and Liabilities with Recurring Fair Value Measurements Fair Value Hierarchy (Details) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2014
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Dec. 31, 2013
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|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||||||||||||
| Cash equivalents | $ 717 | [1] | $ 1,134 | [1] | ||||||||
| Margin deposits | 235 | [2] | 261 | [2] | ||||||||
| Commodity futures contracts | 717 | 434 | ||||||||||
| Commodity forward contracts | 105 | [3] | 107 | [3] | ||||||||
| Interest Rate Swap Assets, Fair Value Disclosure | 7 | 9 | ||||||||||
| Total assets | 1,781 | 1,945 | ||||||||||
| Margin deposits held by us posted by our counterparties | 18 | [2],[4] | 5 | [2],[4] | ||||||||
| Commodity futures contracts | 684 | 495 | ||||||||||
| Commodity forward contracts | 148 | [3] | 70 | [3] | ||||||||
| Interest rate swaps | 126 | 129 | ||||||||||
| Liabilities, Fair Value Disclosure | 976 | 699 | ||||||||||
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Fair Value, Inputs, Level 1 [Member]
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| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||||||||||||
| Cash equivalents | 717 | [1] | 1,134 | [1] | ||||||||
| Margin deposits | 235 | 261 | ||||||||||
| Commodity futures contracts | 717 | 434 | ||||||||||
| Commodity forward contracts | 0 | [3] | 0 | [3] | ||||||||
| Interest Rate Swap Assets, Fair Value Disclosure | 0 | 0 | ||||||||||
| Total assets | 1,669 | 1,829 | ||||||||||
| Margin deposits held by us posted by our counterparties | 18 | 5 | ||||||||||
| Commodity futures contracts | 684 | 495 | ||||||||||
| Commodity forward contracts | 0 | [3] | 0 | [3] | ||||||||
| Interest rate swaps | 0 | 0 | ||||||||||
| Liabilities, Fair Value Disclosure | 702 | 500 | ||||||||||
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Fair Value, Inputs, Level 2 [Member]
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| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||||||||||||
| Cash equivalents | 0 | [1] | 0 | [1] | ||||||||
| Margin deposits | 0 | 0 | ||||||||||
| Commodity futures contracts | 0 | 0 | ||||||||||
| Commodity forward contracts | 69 | [3] | 75 | [3] | ||||||||
| Interest Rate Swap Assets, Fair Value Disclosure | 7 | 9 | ||||||||||
| Total assets | 76 | 84 | ||||||||||
| Margin deposits held by us posted by our counterparties | 0 | 0 | ||||||||||
| Commodity futures contracts | 0 | 0 | ||||||||||
| Commodity forward contracts | 120 | [3] | 52 | [3] | ||||||||
| Interest rate swaps | 126 | 129 | ||||||||||
| Liabilities, Fair Value Disclosure | 246 | 181 | ||||||||||
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Fair Value, Inputs, Level 3 [Member]
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| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||||||||||||
| Cash equivalents | 0 | [1] | 0 | [1] | ||||||||
| Margin deposits | 0 | 0 | ||||||||||
| Commodity futures contracts | 0 | 0 | ||||||||||
| Commodity forward contracts | 36 | [3] | 32 | [3] | ||||||||
| Interest Rate Swap Assets, Fair Value Disclosure | 0 | 0 | ||||||||||
| Total assets | 36 | 32 | ||||||||||
| Margin deposits held by us posted by our counterparties | 0 | 0 | ||||||||||
| Commodity futures contracts | 0 | 0 | ||||||||||
| Commodity forward contracts | 28 | [3] | 18 | [3] | ||||||||
| Interest rate swaps | 0 | 0 | ||||||||||
| Liabilities, Fair Value Disclosure | $ 28 | $ 18 | ||||||||||
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