v2.4.0.8

Fair Value Measurement - FV of Commodity Derivatives (Details 1) (USD $) In Millions, unless otherwise specified | Jun. 30, 2013 | Dec. 31, 2012
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Offsetting Derivative Assets [Abstract] |  |
Assets - gross amounts recognized | $ 1,200 | $ 1,621
Assets - gross amounts offset | 1,064 | 1,403
Assets - net amounts excluding collateral | 136 | 218
Assets - cash collateral | 20 | 29
Asssets - net amounts subject to setoff | 116 | 189
Offsetting Derivative Liabilities [Abstract] |  |
Liabilities - gross amounts recognized | 1,241 | 1,588
Liabilities - gross amounts offset | 1,064 | 1,403
Liabilities - net amounts excluding collateral | 177 | 185
Liabilities - cash collateral | 48 | 16
Liabilities - net amounts subject to setoff | $ 129 | $ 169

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