Fair Value of Financial Assets and Liabilities (Fair Value Measurement Amounts for Assets and Liabilities) (Details) (USD $) In Millions	Jun. 30, 2011		Dec. 31, 2010
Investments in available-for-sale securities, fair value	$ 2,498		$ 2,401
Securities included in investments and other assets	90
Short-term investments	9
Auction Rate Securities [Member]
Investments in available-for-sale securities, fair value	125		149
Short-term investments	9
Auction Rate Securities [Member] | Fair Value [Member]
Investments in available-for-sale securities, fair value	99	[1]	118	[2]
Auction Rate Securities [Member] | Level 2 [Member]
Investments in available-for-sale securities, fair value	9	[1]
Auction Rate Securities [Member] | Level 3 [Member]
Investments in available-for-sale securities, fair value	90	[1]	118	[2]
Equity Securities [Member] | Fair Value [Member]
Other long-term trading and available-for-sale securities	73	[2]	164	[2]
Nuclear decommissioning trust fund securities	1,452		1,365
Equity Securities [Member] | Level 1 [Member]
Other long-term trading and available-for-sale securities	65	[2]	157	[2]
Nuclear decommissioning trust fund securities	1,400		1,313
Equity Securities [Member] | Level 2 [Member]
Other long-term trading and available-for-sale securities	8	[2]	7	[2]
Nuclear decommissioning trust fund securities	47		46
Equity Securities [Member] | Level 3 [Member]
Nuclear decommissioning trust fund securities	5		6
Debt Securities [Member] | Fair Value [Member]
Other long-term trading and available-for-sale securities	220	[2]	221	[2]
Nuclear decommissioning trust fund securities	685		649
Debt Securities [Member] | Level 1 [Member]
Other long-term trading and available-for-sale securities	27	[2]	10	[2]
Nuclear decommissioning trust fund securities	86		35
Debt Securities [Member] | Level 2 [Member]
Other long-term trading and available-for-sale securities	193	[2]	211	[2]
Nuclear decommissioning trust fund securities	551		573
Debt Securities [Member] | Level 3 [Member]
Nuclear decommissioning trust fund securities	48		41
Fair Value [Member]
Derivative assets	156	[3]	186	[3]
Total Assets	2,685		2,703
Derivative liabilities	(129)	[4]	(132)	[4]
Net Assets	2,556		2,571
Level 1 [Member]
Derivative assets	15	[3]	21	[3]
Total Assets	1,593		1,536
Derivative liabilities	(11)	[4]	(8)	[4]
Net Assets	1,582		1,528
Level 2 [Member]
Derivative assets	65	[3]	81	[3]
Total Assets	873		918
Derivative liabilities	(20)	[4]	(21)	[4]
Net Assets	853		897
Level 3 [Member]
Derivative assets	76	[3]	84	[3]
Total Assets	219		249
Derivative liabilities	(98)	[4]	(103)	[4]
Net Assets	$ 121		$ 146

[1] $90 million of these securities are included in Other within Investments and Other Assets and $9 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] Included in Other within Current Liabilities and Other within Deferred Credits and Other Liabilities on the Condensed Consolidated Balance Sheets.