Investment In Long-Term Debt Of Affiliates (Principal Amounts, Coupon Rates, Maturities and Carrying Value) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Investment In Long-Term Debt Of Affiliates [Abstract]
Investment in long-term debt of affiliates (all available-for-sale securities)	$ 4,283		$ 3,632
Available-for-sale securities
Carrying Value	4,283	[1]	3,632	[1]
Cumulative unrealized gains (recorded as other comprehensive income)	(480)	[1],[2]	(61)	[1],[2]
Amortized cost basis	3,803	[1],[3]	3,571	[1],[3]
Impairments	100		94
Debt Securities [Member]
Available-for-sale securities
Principal Amount	4,675		4,508
Carrying Value	4,283	[1]	3,632	[1]
EFH Corp. 10.875% Fixed Senior Notes due November 1, 2017 [Member]
Available-for-sale securities
Principal Amount	1,591		1,591
Carrying Value	1,447	[1]	1,288	[1]
Stated interest rate (as a percent)	10.875%
Unaffliated parties, percentage of debt held (as a percent)	11.00%
EFH Corp. 11.25/12.00% Senior Toggle Notes due November 1, 2017 [Member]
Available-for-sale securities
Principal Amount	2,951		2,784
Carrying Value	2,774	[1]	2,283	[1]
Effective interest rate (as a percent)	11.25%		12.00%
Unaffliated parties, percentage of debt held (as a percent)	14.00%
EFH Corp. 5.55% Fixed Senior Notes Series P due November 15, 2014 [Member]
Available-for-sale securities
Principal Amount	45		45
Carrying Value	36	[1]	30	[1]
Stated interest rate (as a percent)	5.55%
EFH Corp. 6.50% Fixed Senior Notes Series Q due November 15, 2024 [Member]
Available-for-sale securities
Principal Amount	6		6
Carrying Value	3	[1]	2	[1]
Stated interest rate (as a percent)	6.50%
EFH Corp. 6.55% Fixed Senior Notes Series R due November 15, 2034 [Member]
Available-for-sale securities
Principal Amount	3		3
Carrying Value	2	[1]	2	[1]
Stated interest rate (as a percent)	6.55%
TCEH 10.25% Fixed Senior Notes due November 1, 2015 (both periods include $48 million principal amount of Series B Notes) [Member]
Available-for-sale securities
Principal Amount	79		79
Carrying Value	21	[1]	27	[1]
Stated interest rate (as a percent)	10.25%
10.25% Fixed Senior Notes due November 1, 2015, Series B [Member]
Available-for-sale securities
Principal Amount	$ 48		$ 48

[1] Carrying value equals fair value.

[2] 2012 amount reflects unrealized gains on all EFH Corp. securities. 2011 amount reflects unrealized gain on EFH Corp. Toggle Notes.

[3] 2012 amount is net of impairments in 2010 through 2012 totaling $100 million. 2011 amount is net of impairments in 2010 and 2011 totaling $94 million.