Supplemental Guarantor Condensed Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	$ (121)	$ 329
Cash flows – financing activities:
Notes/advances due to affiliates	4	0
Repayments/repurchases of long-term debt	(94)	(30)
Net short-term borrowings under accounts receivable securitization program	90	80
Contributions from noncontrolling interests	3	6
Sale/leaseback of equipment	0	15
Other, net	(10)	0
Cash used in financing activities	(7)	(493)
Cash flows – investing activities:
Capital expenditures	(353)	(498)
Nuclear fuel purchases	(59)	(155)
Notes due from affiliates	698	922
Purchase of right to use certain computer-related assets from parent	(6)	0
Proceeds from sales of assets	3	1
Acquisition of combustion turbine trust interest	(40)
Purchases of environmental allowances and credits	(13)	(19)
Proceeds from sales of nuclear decommissioning trust fund securities	128	56
Investments in nuclear decommissioning trust fund securities	(140)	(68)
Other, net	3	(2)
Cash provided by (used in) investing activities	215	353
Net change in cash and cash equivalents	87	189
Cash and cash equivalents – beginning balance	1,175	120
Cash and cash equivalents – ending balance	1,262	309
Proceeds from (Repayments of) Short-term Debt	0	(385)
Decrease In Income Tax Related Note Payable To Related Parties	0	(20)
Settlement of reimbursement agreements with Oncor (Note 11)	0	(159)
Increase Decrease In Other Restricted Cash	0	(112)
Parent/ Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	(8)	(7)
Cash flows – financing activities:
Notes/advances due to affiliates	11	11
Repayments/repurchases of long-term debt	(3)	(4)
Net short-term borrowings under accounts receivable securitization program	0	0
Contributions from noncontrolling interests	0	0
Sale/leaseback of equipment		0
Other, net	0
Cash used in financing activities	8	7
Cash flows – investing activities:
Capital expenditures	0	0
Nuclear fuel purchases	0	0
Notes due from affiliates	0	0
Purchase of right to use certain computer-related assets from parent	0
Proceeds from sales of assets	0	0
Acquisition of combustion turbine trust interest	0
Purchases of environmental allowances and credits	0	0
Proceeds from sales of nuclear decommissioning trust fund securities	0	0
Investments in nuclear decommissioning trust fund securities	0	0
Other, net	0	0
Cash provided by (used in) investing activities	0	0
Net change in cash and cash equivalents	0	0
Cash and cash equivalents – beginning balance	0	0
Cash and cash equivalents – ending balance	0	0
Proceeds from (Repayments of) Short-term Debt		0
Decrease In Income Tax Related Note Payable To Related Parties		0
Settlement of reimbursement agreements with Oncor (Note 11)		0
Increase Decrease In Other Restricted Cash		0
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	(1,764)	(471)
Cash flows – financing activities:
Notes/advances due to affiliates	1,913	1,029
Repayments/repurchases of long-term debt	(64)	0
Net short-term borrowings under accounts receivable securitization program	0	0
Contributions from noncontrolling interests	0	0
Sale/leaseback of equipment		0
Other, net	0
Cash used in financing activities	1,849	644
Cash flows – investing activities:
Capital expenditures	0	0
Nuclear fuel purchases	0	0
Notes due from affiliates	0	0
Purchase of right to use certain computer-related assets from parent	0
Proceeds from sales of assets	0	0
Acquisition of combustion turbine trust interest	0
Purchases of environmental allowances and credits	0	0
Proceeds from sales of nuclear decommissioning trust fund securities	0	0
Investments in nuclear decommissioning trust fund securities	0	0
Other, net	0	0
Cash provided by (used in) investing activities	0	0
Net change in cash and cash equivalents	85	173
Cash and cash equivalents – beginning balance	1,115	87
Cash and cash equivalents – ending balance	1,200	260
Proceeds from (Repayments of) Short-term Debt		(385)
Decrease In Income Tax Related Note Payable To Related Parties		0
Settlement of reimbursement agreements with Oncor (Note 11)		0
Increase Decrease In Other Restricted Cash		0
Other Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	1,736	885
Cash flows – financing activities:
Notes/advances due to affiliates	0	0
Repayments/repurchases of long-term debt	(27)	(26)
Net short-term borrowings under accounts receivable securitization program	0	0
Contributions from noncontrolling interests	0	0
Sale/leaseback of equipment		15
Other, net	0
Cash used in financing activities	(27)	(190)
Cash flows – investing activities:
Capital expenditures	(349)	(491)
Nuclear fuel purchases	(59)	(155)
Notes due from affiliates	(1,222)	(118)
Purchase of right to use certain computer-related assets from parent	(6)
Proceeds from sales of assets	3	1
Acquisition of combustion turbine trust interest	(40)
Purchases of environmental allowances and credits	(13)	(19)
Proceeds from sales of nuclear decommissioning trust fund securities	128	56
Investments in nuclear decommissioning trust fund securities	(140)	(68)
Other, net	3	(2)
Cash provided by (used in) investing activities	(1,701)	(680)
Net change in cash and cash equivalents	8	15
Cash and cash equivalents – beginning balance	15	23
Cash and cash equivalents – ending balance	23	38
Proceeds from (Repayments of) Short-term Debt		0
Decrease In Income Tax Related Note Payable To Related Parties		(20)
Settlement of reimbursement agreements with Oncor (Note 11)		(159)
Increase Decrease In Other Restricted Cash		(112)
Non-guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	(85)	(78)
Cash flows – financing activities:
Notes/advances due to affiliates	0	0
Repayments/repurchases of long-term debt	0	0
Net short-term borrowings under accounts receivable securitization program	90	80
Contributions from noncontrolling interests	3	6
Sale/leaseback of equipment		0
Other, net	(10)
Cash used in financing activities	83	86
Cash flows – investing activities:
Capital expenditures	(4)	(7)
Nuclear fuel purchases	0	0
Notes due from affiliates	0	0
Purchase of right to use certain computer-related assets from parent	0
Proceeds from sales of assets	0	0
Acquisition of combustion turbine trust interest	0
Purchases of environmental allowances and credits	0	0
Proceeds from sales of nuclear decommissioning trust fund securities	0	0
Investments in nuclear decommissioning trust fund securities	0	0
Other, net	0	0
Cash provided by (used in) investing activities	(4)	(7)
Net change in cash and cash equivalents	(6)	1
Cash and cash equivalents – beginning balance	45	10
Cash and cash equivalents – ending balance	39	11
Proceeds from (Repayments of) Short-term Debt		0
Decrease In Income Tax Related Note Payable To Related Parties		0
Settlement of reimbursement agreements with Oncor (Note 11)		0
Increase Decrease In Other Restricted Cash		0
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash provided by (used in) operating activities	0	0
Cash flows – financing activities:
Notes/advances due to affiliates	(1,920)	(1,040)
Repayments/repurchases of long-term debt	0	0
Net short-term borrowings under accounts receivable securitization program	0	0
Contributions from noncontrolling interests	0	0
Sale/leaseback of equipment		0
Other, net	0
Cash used in financing activities	(1,920)	(1,040)
Cash flows – investing activities:
Capital expenditures	0	0
Nuclear fuel purchases	0	0
Notes due from affiliates	1,920	1,040
Purchase of right to use certain computer-related assets from parent	0
Proceeds from sales of assets	0	0
Acquisition of combustion turbine trust interest	0
Purchases of environmental allowances and credits	0	0
Proceeds from sales of nuclear decommissioning trust fund securities	0	0
Investments in nuclear decommissioning trust fund securities	0	0
Other, net	0	0
Cash provided by (used in) investing activities	1,920	1,040
Net change in cash and cash equivalents	0	0
Cash and cash equivalents – beginning balance	0	0
Cash and cash equivalents – ending balance	0	0
Proceeds from (Repayments of) Short-term Debt		0
Decrease In Income Tax Related Note Payable To Related Parties		0
Settlement of reimbursement agreements with Oncor (Note 11)		0
Increase Decrease In Other Restricted Cash		$ 0