Long-Term Debt (Guarantees and Push Down of EFH Corp. Debt) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Push Down Debt [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 721	$ 709
Energy Future Holdings Corp. [Member] | Push Down Debt [Member]
Debt Instrument [Line Items]
Percentage of principal plus unamortized premium of related party Merger-related debt guaranteed by parent company (as a percent)	50.00%
Financial Guarantee [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes And Demand Notes Payable [Member]
Debt Instrument [Line Items]
Total	7,067	7,777
Financial Guarantee [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	6,378	6,185
Financial Guarantee [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 10% Senior Secured Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	1,061	1,061
Financial Guarantee [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 9.75% Senior Secured Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	115	115
Financial Guarantee [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 10.875% Senior Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	1,787	1,787
Financial Guarantee [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 11.25 / 12.00% Senior Toggle Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	3,415	3,222
Financial Guarantee [Member] | Energy Future Intermediate Holding CO LLC [Member] | Demand Notes Payable [Member] | EFH Corp. P&I and SG&A demand notes payable to TCEH (Note 7) [Member]
Debt Instrument [Line Items]
Intercompany payables	689	1,592
Financial Guarantee [Member] | Held By EFIH [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	4,542	4,375
Financial Guarantee [Member] | Held By EFIH [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 10.875% Senior Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	1,591	1,591
Financial Guarantee [Member] | Held By EFIH [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 11.25 / 12.00% Senior Toggle Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	2,951	2,784
Financial Guarantee [Member] | Subject to Push Down [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	1,436	1,410
Financial Guarantee [Member] | Subject to Push Down [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 10% Senior Secured Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	661	661
Financial Guarantee [Member] | Subject to Push Down [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 9.75% Senior Secured Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	115	115
Financial Guarantee [Member] | Subject to Push Down [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 10.875% Senior Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	196	196
Financial Guarantee [Member] | Subject to Push Down [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 11.25 / 12.00% Senior Toggle Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	464	438
Financial Guarantee [Member] | Not Merger-Related [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	400	400
Financial Guarantee [Member] | Not Merger-Related [Member] | Energy Future Intermediate Holding CO LLC [Member] | Senior Notes [Member] | EFH Corp. 10% Senior Secured Notes [Member]
Debt Instrument [Line Items]
Securities Guaranteed (principal amounts)	$ 400	$ 400