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
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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