v2.4.0.6

Fair Value Fair Value of Derivative Contracts (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Estimate of Fair Value [Member] Commodity Contract [Member]	Dec. 31, 2012 Estimate of Fair Value [Member] Commodity Contract [Member]	Mar. 31, 2013 Estimate of Fair Value [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Estimate of Fair Value [Member] Interest Rate Swap [Member]	Mar. 31, 2013 Quoted prices in active markets for identical assets (Level 1) [Member] Commodity Contract [Member]	Dec. 31, 2012 Quoted prices in active markets for identical assets (Level 1) [Member] Commodity Contract [Member]	Mar. 31, 2013 Quoted prices in active markets for identical assets (Level 1) [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Quoted prices in active markets for identical assets (Level 1) [Member] Interest Rate Swap [Member]	Mar. 31, 2013 Significant other observable inputs (Level 2) [Member] Commodity Contract [Member]	Dec. 31, 2012 Significant other observable inputs (Level 2) [Member] Commodity Contract [Member]	Mar. 31, 2013 Significant other observable inputs (Level 2) [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Significant other observable inputs (Level 2) [Member] Interest Rate Swap [Member]	Mar. 31, 2013 Significantunobservable inputs (Level 3) [Member] Commodity Contract [Member]	Dec. 31, 2012 Significantunobservable inputs (Level 3) [Member] Commodity Contract [Member]	Mar. 31, 2013 Significantunobservable inputs (Level 3) [Member] Interest Rate Swap [Member]	Dec. 31, 2012 Significantunobservable inputs (Level 3) [Member] Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets			$ 78	$ 107	$ 579	$ 665	$ 2	$ 3	$ 0	$ 0	$ 57	$ 76	$ 579	$ 665	$ 19	$ 28	$ 0	$ 0
Fair Value, Assets Liabilites Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning of Period	(155)	7
Total gains (losses), Included in earnings	5	2
Total gains (losses), Included in other comprehensive income	(1)	(22)
Purchases	0	3
Settlements	9	7
End of Period	(142)	(3)
The amount of total gains or (losses) for the period included in earnings attributable to the change in unrealized gains or (losses) relating to assets held at the reporting date	(1)	2
Liability fair value, derivative			$ (217)	$ (212)	$ (3)	$ (1)	$ (17)	$ (3)	$ 0	$ 0	$ (39)	$ (26)	$ (3)	$ (1)	$ (161)	$ (183)	$ 0	$ 0

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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Liability Net, Gain (Loss) Included in Earnings

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Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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Derivative instrument obligations meeting the definition of a liability which the Company is a party to as of the balance sheet date.

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This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income (or changes in net assets) in investment income. Such unrealized (holding) gains or losses relate to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

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