Risk Management Effect of Derivative Contracts on the Income Statement (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Other Comprehensive Income (Loss) [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss)recognized in OCI on derivative(effective portion)	$ 228	[1]	$ 126	[1]	$ 142	[1]	$ (75)	[1]
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss to be reclassified within twelve months					(4)
Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in income on derivative	196	[2]	143	[2]	81	[2]	72	[2]
Interest Rate Swap [Member] | Other Comprehensive Income (Loss) [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss)recognized in OCI on derivative(effective portion)	(3)	[1]	0	[1]	(3)	[1]	0	[1]
Interest Rate Swap [Member] | Interest expense [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in income on derivative	196	[2]	143	[2]	81	[2]	72	[2]
Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss to be reclassified within twelve months					57
Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss)reclassified fromAccumulated OCIinto income(effective portion)	8	[3]	(64)	[3]	(15)	[3]	(102)	[3]
Amount of gain/(loss)recognized in incomeon derivative(ineffective portionand amountexcluded fromeffectiveness testing)	0		(2)		(3)		2
Commodity Contract [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in income on derivative	(196)	[2]	(143)	[2]	(81)	[2]	(72)	[2]
Commodity Contract [Member] | Other Comprehensive Income (Loss) [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss)recognized in OCI on derivative(effective portion)	231	[1]	126	[1]	145	[1]	(75)	[1]
Commodity Contract [Member] | Revenues Natural Gas Sales [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss)reclassified fromAccumulated OCIinto income(effective portion)	1	[3]	0	[3]	2	[3]	0	[3]
Amount of gain/(loss)recognized in incomeon derivative(ineffective portionand amountexcluded fromeffectiveness testing)	0		0
Commodity Contract [Member] | Interest expense [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in income on derivative	(196)	[2]	(143)	[2]	(81)	[2]	(72)	[2]
Commodity Contract [Member] | Revenues-Product sales and other [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss)reclassified fromAccumulated OCIinto income(effective portion)	(2)	[3]	(64)	[3]	(23)	[3]	(109)	[3]
Amount of gain/(loss)recognized in incomeon derivative(ineffective portionand amountexcluded fromeffectiveness testing)	0		(2)		(3)		2
Commodity Contract [Member] | Gas purchases and other costs of sales [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss)reclassified fromAccumulated OCIinto income(effective portion)	9	[3]	0	[3]	6	[3]	7	[3]
Amount of gain/(loss)recognized in incomeon derivative(ineffective portionand amountexcluded fromeffectiveness testing)	$ 0		$ 0		$ 0		$ 0

[1] We expect to reclassify an approximate $57 million gain associated with energy commodity price risk management activities, and included in our accumulated other comprehensive loss and noncontrolling interest balances as of June 30, 2012, into earnings during the next twelve months (when the associated forecast sales and purchases are also expected to occur), however, actual amounts reclassified into earnings could vary materially as a result of changes in market prices.

[2] Amounts reflect the change in the fair value of interest rate swap agreements and the change in the fair value of the associated fixed rate debt which exactly offset each other as a result of no hedge ineffectiveness.

[3] No material amounts were reclassified into earnings as a result of the discontinuance of cash flow hedges because it was probable that the original forecast transactions would no longer occur by the end of the originally specified time period or within an additional two-month period of time thereafter, but rather, the amounts reclassified were the result of the hedged forecast transactions actually affecting earnings (i.e., when the forecast sales and purchase actually occurred).