Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2011		Dec. 31, 2010
Total assets	$ 293		$ 272
Transfer in	5	[1],[2]	(45)	[1],[2],[3]
Transfer out	(5)	[1],[2]	45	[1],[2],[3]
Derivative liabilities	136	[4]	191	[5]
Total liabilities	146		201
Commodity [Member]
Derivative assets	115	[4]	106	[5]
Derivative liabilities	136		191
Commodity [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative assets	1	[4]	2	[5]
Derivative liabilities	4		4
Commodity [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative assets	56	[4]	72	[5]
Derivative liabilities	144		270
Commodity [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative assets	100	[4]	144	[5]
Derivative liabilities	130		205
Commodity [Member] | Netting Adjustments [Member]
Derivative assets	(42)	[4],[6]	(112)	[5],[6]
Derivative liabilities	(142)	[6]	(288)	[6]
Fair Value Interest Rate Contract [Member]
Derivative liabilities	10	[7]	10	[8]
Fair Value Interest Rate Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative liabilities				[8]
Fair Value Interest Rate Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative liabilities				[8]
Fair Value Interest Rate Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative liabilities	10	[7]	10	[8]
Fair Value Interest Rate Contract [Member] | Netting Adjustments [Member]
Derivative liabilities				[6],[8]
Fair Value Other Assets [Member]
Derivative assets	178	[9]	166	[9]
Fair Value Other Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative assets	72	[9]	65	[9]
Fair Value Other Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative assets				[9]
Fair Value Other Assets [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative assets	106	[9]	101	[9]
Fair Value Other Assets [Member] | Netting Adjustments [Member]
Derivative assets				[6],[9]
Fair Value, Inputs, Level 1 [Member]
Total assets	73		67
Transfer in	0	[1],[2]		[1],[2],[3]
Transfer out	0	[1],[2]		[1],[2],[3]
Derivative liabilities	4	[4]	4	[5]
Total liabilities	4		4
Fair Value, Inputs, Level 2 [Member]
Total assets	56		72
Transfer in	5	[1],[2]	(36)	[1],[2],[3]
Transfer out			9	[1],[2],[3]
Derivative liabilities	149	[4]	243	[5]
Total liabilities	149		243
Fair Value, Inputs, Level 3 [Member]
Total assets	206		245
Transfer in			(9)	[1],[2],[3]
Transfer out	(5)	[1],[2]	36	[1],[2],[3]
Derivative liabilities	125	[4]	232	[5]
Total liabilities	135		242
Netting Adjustments [Member]
Total assets	(42)	[6]	(112)	[6]
Transfer in				[1],[2],[3],[6]
Transfer out				[1],[2],[3],[6]
Derivative liabilities	(142)	[4],[6]	(288)	[5],[6]
Total liabilities	$ (142)	[6]	$ (288)	[6]

[1] The Companies' policy is to recognize transfers into and transfers out of the levels at the end of the reporting period.

[2] Transferred from Level 3 to Level 2 because of availability of observable market data due to decrease in the terms of certain contracts from beyond one year as of December 31, 2010 to less than one year as of June 30, 2011.

[3] Transferred from Level 2 to Level 3 because of reassessment of the levels in the fair value hierarchy within which certain inputs fall.

[4] A significant portion of the commodity derivative contracts categorized in Level 3 is valued using either an industry acceptable model or an internally developed model with observable inputs. The models also include some less readily observable inputs resulting in the classification of the entire contract as Level 3. See Note I.

[5] A significant portion of the commodity derivative contracts categorized in Level 3 is valued using either an industry acceptable model or an internally developed model with observable inputs. The models also include some less readily observable inputs resulting in the classification of the entire contract as Level 3. See Note O to the financial statements in Item 8 of the Form 10-K.

[6] Amounts represent the impact of legally-enforceable master netting agreements that allow the Companies to net gain and loss positions and cash collateral held or placed with the same counterparties.

[7] See Note I.

[8] See Note O to the financial statements in Item 8 of the Form 10-K.

[9] Other assets are comprised of assets such as life insurance contracts within the Deferred Income Plan and Supplemental Retirement Income Plans, held in rabbi trusts.