Fair Value Of Financial Assets And Liabilities (Fair Value Measurement Amounts For Assets And Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Investments in available-for-sale securities, fair value	$ 71	[1]	$ 118	[1]
Derivative assets	74	[2]	186	[2]
Total Assets	2,655		2,703
Derivative liabilities	(264)	[3]	(132)	[3]
Net Assets	2,391		2,571
Level 1 [Member]
Investments in available-for-sale securities, fair value		[1]		[1]
Derivative assets	43	[2]	21	[2]
Total Assets	1,520		1,536
Derivative liabilities	(36)	[3]	(8)	[3]
Net Assets	1,484		1,528
Level 2 [Member]
Investments in available-for-sale securities, fair value		[1]		[1]
Derivative assets	6	[2]	81	[2]
Total Assets	986		918
Derivative liabilities	(164)	[3]	(21)	[3]
Net Assets	822		897
Level 3 [Member]
Investments in available-for-sale securities, fair value	71	[1]	118	[1]
Derivative assets	25	[2]	84	[2]
Total Assets	149		249
Derivative liabilities	(64)	[3]	(103)	[3]
Net Assets	85		146
Equity Securities [Member]
Nuclear decommissioning trust fund securities	1,337		1,365
Other trading and available-for-sale securities	68		164	[1]
Equity Securities [Member] | Level 1 [Member]
Nuclear decommissioning trust fund securities	1,285		1,313
Other trading and available-for-sale securities	61		157	[1]
Equity Securities [Member] | Level 2 [Member]
Nuclear decommissioning trust fund securities	46		46
Other trading and available-for-sale securities	7		7	[1]
Equity Securities [Member] | Level 3 [Member]
Nuclear decommissioning trust fund securities	6		6
Other trading and available-for-sale securities				[1]
Debt Securities [Member]
Nuclear decommissioning trust fund securities	723		649
Other trading and available-for-sale securities	382	[4]	221	[1]
Debt Securities [Member] | Level 1 [Member]
Nuclear decommissioning trust fund securities	109		35
Other trading and available-for-sale securities	22	[4]	10	[1]
Debt Securities [Member] | Level 2 [Member]
Nuclear decommissioning trust fund securities	567		573
Other trading and available-for-sale securities	360	[4]	211	[1]
Debt Securities [Member] | Level 3 [Member]
Nuclear decommissioning trust fund securities	47		41
Other trading and available-for-sale securities		[4]		[1]

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

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

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

[4] Included in Other within Investments and Other Assets and Short-term Investments on the Consolidated Balance Sheets.