Fair Value Of Financial Assets And Liabilities (Fair Value Measurement Amounts For Assets And Liabilities) (Details) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010
Short-term investments	$ 146
Auction Rate Securities [Member]
Investments in available-for-sale securities, fair value	115		149
Securities included in investments and other assets	72
Short-term investments	25
Auction Rate Securities [Member] | Fair Value [Member]
Investments in available-for-sale securities, fair value	97	[1]	118	[2]
Auction Rate Securities [Member] | Level 2 [Member]
Investments in available-for-sale securities, fair value	25	[1]
Auction Rate Securities [Member] | Level 3 [Member]
Investments in available-for-sale securities, fair value	72	[1]	118	[2]
Equity Securities [Member] | Fair Value [Member]
Other long-term trading and available-for-sale securities	62	[3]	164	[2]
Nuclear decommissioning trust fund equity securities	1,206		1,365
Equity Securities [Member] | Level 1 [Member]
Other long-term trading and available-for-sale securities	55	[3]	157	[2]
Nuclear decommissioning trust fund equity securities	1,154		1,313
Equity Securities [Member] | Level 2 [Member]
Other long-term trading and available-for-sale securities	7	[3]	7	[2]
Nuclear decommissioning trust fund equity securities	46		46
Equity Securities [Member] | Level 3 [Member]
Nuclear decommissioning trust fund equity securities	6		6
Debt Securities [Member]
Securities included in investments and other assets	209
Short-term investments	121
Debt Securities [Member] | Fair Value [Member]
Other long-term trading and available-for-sale securities	330	[4]	221	[2]
Nuclear decommissioning trust fund equity securities	718		649
Debt Securities [Member] | Level 1 [Member]
Other long-term trading and available-for-sale securities	27	[4]	10	[2]
Nuclear decommissioning trust fund equity securities	151		35
Debt Securities [Member] | Level 2 [Member]
Other long-term trading and available-for-sale securities	303	[4]	211	[2]
Nuclear decommissioning trust fund equity securities	519		573
Debt Securities [Member] | Level 3 [Member]
Nuclear decommissioning trust fund equity securities	48		41
Fair Value [Member]
Derivative assets	89	[3]	186	[3]
Total Assets	2,502		2,703
Derivative liabilities	(349)	[5]	(132)	[5]
Net Assets	2,153		2,571
Level 1 [Member]
Derivative assets	15	[3]	21	[3]
Total Assets	1,402		1,536
Derivative liabilities	(57)	[5]	(8)	[5]
Net Assets	1,345		1,528
Level 2 [Member]
Derivative assets	9	[3]	81	[3]
Total Assets	909		918
Derivative liabilities	(203)	[5]	(21)	[5]
Net Assets	706		897
Level 3 [Member]
Derivative assets	65	[3]	84	[3]
Total Assets	191		249
Derivative liabilities	(89)	[5]	(103)	[5]
Net Assets	$ 102		$ 146

[1] $72 million of these securities are included in Other within Investments and Other Assets and $25 million are classified as Short-Term Investments on the Condensed Consolidated Balance Sheets.

[2] Included in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.

[3] Included in Other within Current Assets and Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.

[4] $209 million of these securities are included in Other within Investments and Other Assets and $121 million are classified as Short-Term Investments on the Condensed Consolidated Balance Sheets.

[5] Included in Other within Current Liabilities and Other within Deferred Credits and Other Liabilities on the Condensed Consolidated Balance Sheets.