Debtor-In-Possession Borrowing Facility and Long-Term Debt Not Subject to Compromise - Long-Term Debt Not Subject to Compromise (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities		$ 98	$ 120
Less amounts due currently		(32)	(35)
Long-term debt, less amounts due currently (Note 8)		66	85
Energy Future Competitive Holdings Company [Member]
Debt Instrument [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities		44	47
Unamortized fair value discount (b)	[1]	$ (2)	(3)
Energy Future Competitive Holdings Company [Member] | Notes Payable to Banks [Member] | Fixed 9.58% Notes due in annual installments through December 4, 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		9.58%
Long-term Debt and Capital Lease Obligations, Including Current Maturities	[2]	$ 21	21
Energy Future Competitive Holdings Company [Member] | Notes Payable to Banks [Member] | Fixed 8.254% Notes due in quarterly installments through December 31, 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		8.254%
Long-term Debt and Capital Lease Obligations, Including Current Maturities	[2]	$ 25	29
Texas Competitive Electric Holdings Company LLC
Debt Instrument [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities		54	73
Capital lease obligations		40	44
Other		2	2
Unamortized discount		$ (1)	(2)
Texas Competitive Electric Holdings Company LLC | Fixed Secured Facility Bonds [Member] | Fixed 7.48% Secured Facility Bonds With Amortizing Payments Through January 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		7.48%
Long-term Debt and Capital Lease Obligations, Including Current Maturities	[3]	$ 13	25
Texas Competitive Electric Holdings Company LLC | Fixed Secured Facility Bonds [Member] | Fixed 7.46% Secured Facility Bonds with amortizing payments through January 2015 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		7.46%
Long-term Debt and Capital Lease Obligations, Including Current Maturities	[3]	$ 0	$ 4

[1] Approved by the Bankruptcy Court for repayment.

[2] Amount represents unamortized fair value adjustments recorded under purchase accounting.

[3] Debt issued by trust and secured by assets held by the trust.