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Risk Management Energy Commodity Price Risk Managment (Details)
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Mar. 31, 2013
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|---|---|
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Crude Oil [Member]
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| Derivative [Line Items] | |
| Net open position long/(short) | (3,600,000) |
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Natural Gas Fixed Price [Member]
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| Derivative [Line Items] | |
| Net open position long/(short) | (33,900,000,000) |
| Net open position long/(short) | (2,000,000,000) |
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Natural Gas Basis [Member]
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| Derivative [Line Items] | |
| Net open position long/(short) | (34,400,000,000) |
| Net open position long/(short) | 13,100,000,000 |
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Crude Oil Fixed Price [Member]
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| Derivative [Line Items] | |
| Net open position long/(short) | (21,400,000) |
| Net open position long/(short) | (100,000) |