Fair Value Measurements (Details) (USD $)	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Dec. 31, 2011
Book Values and Fair Values of Long - term Debt
Total Long-term Debt Outstanding	$ 17,320,000,000				$ 16,516,000,000
Long Term Debt, Fair Value	19,533,000,000				19,259,000,000
Other Temporary Investments
Estimated Fair Value	217,000,000				294,000,000
Debt And Equity Securities Within Other Temporary Investments [Abstract]
Proceeds from Investment Sales	0		196,000,000
Purchases of Investments	0		148,000,000
Gross Realized Gains on Investment Sales	0		0
Gross Realized Losses on Investment Sales	0		0
Accumulated Other Comprehesive Income Loss Activity for Other Temporary Investments
Balance in AOCI	2,000,000
Change in Fair Value Recognized in AOCI	2,000,000
Amount of (Gain) or Loss Reclassified from AOCI to Statement of Income: Interst Income	0
Balance in AOCI	4,000,000
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	1,662,000,000				1,592,000,000
Gross Unrealized Gains	340,000,000				281,000,000
Other-Than-Temporary Impairments	(83,000,000)				(85,000,000)
Securities Activity Within Decommissioning And SNF Trusts [Abstract]
Proceeds from Investment Sales	334,000,000		288,000,000
Purchases of Investments	353,000,000		306,000,000
Gross Realized Gains on Investment Sales	2,000,000		5,000,000
Gross Realized Losses on Investment Sales	1,000,000		5,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	1,662,000,000				1,592,000,000
Assets:
Cash and Cash Equivalents	286,000,000	[1]			221,000,000	[1]
Total Other Temporary Investments	217,000,000				294,000,000
Risk Management Assets
Risk Management Assets	671,000,000				596,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	1,662,000,000				1,592,000,000
Total Assets	2,836,000,000				2,703,000,000
Liabilities:
Risk Management Liabilities	424,000,000				345,000,000
Changes in the fair value of net trading derivatives and other investments
Beginning Balance	69,000,000		85,000,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets)	(12,000,000)	[2],[3]	(2,000,000)	[2],[3]
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date	3,000,000	[2]	(4,000,000)	[2]
Realized and Unrealized Gains (Losses) Included in Other Comprehensive Income	1,000,000		0
Purchases, Issuances and Settlements	16,000,000	[4]	(8,000,000)	[4]
Transfers into Level 3	17,000,000	[5],[6]	0	[5],[6]
Transfers out of Level 3	(12,000,000)	[6],[7]	8,000,000	[6],[7]
Changes in Fair Value Allocated to Regulated Jurisdictions	10,000,000	[8]	10,000,000	[8]
Ending Balance	92,000,000		73,000,000
Fair Value Measurements (Textuals) [Abstract]
Adjusted Cost of Debt Securities	869,000,000				862,000,000
Adjusted Cost of Domestic Equity Securities	434,000,000				431,000,000
Level 1 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	720,000,000				646,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	720,000,000				646,000,000
Assets:
Cash and Cash Equivalents	24,000,000	[1]			6,000,000	[1]
Total Other Temporary Investments	189,000,000				269,000,000
Risk Management Assets
Risk Management Assets	78,000,000				62,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	720,000,000				646,000,000
Total Assets	1,011,000,000				983,000,000
Liabilities:
Risk Management Liabilities	53,000,000				43,000,000
Level 2 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	933,000,000				933,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	933,000,000				933,000,000
Assets:
Cash and Cash Equivalents	0	[1]			0	[1]
Total Other Temporary Investments	0				0
Risk Management Assets
Risk Management Assets	1,865,000,000				1,322,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	933,000,000				933,000,000
Total Assets	2,798,000,000				2,255,000,000
Liabilities:
Risk Management Liabilities	1,845,000,000				1,294,000,000
Level 3 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Assets:
Cash and Cash Equivalents	0	[1]			0	[1]
Total Other Temporary Investments	0				0
Risk Management Assets
Risk Management Assets	170,000,000				147,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
Total Assets	170,000,000				147,000,000
Liabilities:
Risk Management Liabilities	78,000,000				78,000,000
Fair Value Inputs Other [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	9,000,000				13,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	9,000,000				13,000,000
Assets:
Cash and Cash Equivalents	262,000,000	[1]			215,000,000	[1]
Total Other Temporary Investments	28,000,000				25,000,000
Risk Management Assets
Risk Management Assets	(1,442,000,000)				(935,000,000)
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	9,000,000				13,000,000
Total Assets	(1,143,000,000)				(682,000,000)
Liabilities:
Risk Management Liabilities	(1,552,000,000)				(1,070,000,000)
Cash [Member]
Other Temporary Investments
Cost	137,000,000	[9]			216,000,000	[9]
Gross Unrealized Gains	0				0
Gross Unrealized Losses	0				0
Assets:
Total Other Temporary Investments	137,000,000	[1]			216,000,000	[1]
Cash [Member] | Level 1 [Member]
Assets:
Total Other Temporary Investments	109,000,000	[1]			191,000,000	[1]
Cash [Member] | Level 2 [Member]
Assets:
Total Other Temporary Investments	0	[1]			0	[1]
Cash [Member] | Level 3 [Member]
Assets:
Total Other Temporary Investments	0	[1]			0	[1]
Cash [Member] | Fair Value Inputs Other [Member]
Assets:
Total Other Temporary Investments	28,000,000	[1]			25,000,000	[1]
Fixed Income Funds [Member]
Nuclear Trust Fund Investments [Abstract]
Gross Unrealized Gains	54,000,000				66,000,000
Other-Than-Temporary Impairments	(3,000,000)				(5,000,000)
Mutual Funds Fixed Income [Member]
Other Temporary Investments
Cost	64,000,000				64,000,000
Gross Unrealized Gains	0				0
Gross Unrealized Losses	0				0
Assets:
Total Other Temporary Investments	64,000,000				64,000,000
Mutual Funds Fixed Income [Member] | Level 1 [Member]
Assets:
Total Other Temporary Investments	64,000,000				64,000,000
Mutual Funds Fixed Income [Member] | Level 2 [Member]
Assets:
Total Other Temporary Investments	0				0
Mutual Funds Fixed Income [Member] | Level 3 [Member]
Assets:
Total Other Temporary Investments	0				0
Mutual Funds Fixed Income [Member] | Fair Value Inputs Other [Member]
Assets:
Total Other Temporary Investments	0				0
Variable Rate Demand Notes [Member]
Other Temporary Investments
Cost	0				0
Gross Unrealized Gains	0				0
Gross Unrealized Losses	0				0
Equity Securities - Domestic [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value					646,000,000	[10]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities					646,000,000	[10]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts					646,000,000	[10]
Equity Securities - Domestic [Member] | Level 1 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value					646,000,000	[10]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities					646,000,000	[10]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts					646,000,000	[10]
Domestic [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	720,000,000	[10]
Gross Unrealized Gains	286,000,000				215,000,000
Other-Than-Temporary Impairments	(80,000,000)				(80,000,000)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	720,000,000	[10]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	720,000,000	[10]
Domestic [Member] | Level 1 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	720,000,000	[10]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	720,000,000	[10]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	720,000,000	[10]
Domestic [Member] | Level 2 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0	[10]			0	[10]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0	[10]			0	[10]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0	[10]			0	[10]
Domestic [Member] | Level 3 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0	[10]			0	[10]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0	[10]			0	[10]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0	[10]			0	[10]
Domestic [Member] | Fair Value Inputs Other [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0	[10]			0	[10]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0	[10]			0	[10]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0	[10]			0	[10]
Mutual Funds Equity [Member]
Other Temporary Investments
Cost	11,000,000				11,000,000
Gross Unrealized Gains	5,000,000				3,000,000
Gross Unrealized Losses	0				0
Assets:
Total Other Temporary Investments	16,000,000	[10]			14,000,000	[10]
Mutual Funds Equity [Member] | Level 1 [Member]
Assets:
Total Other Temporary Investments	16,000,000	[10]			14,000,000	[10]
Mutual Funds Equity [Member] | Level 2 [Member]
Assets:
Total Other Temporary Investments	0	[10]			0	[10]
Mutual Funds Equity [Member] | Level 3 [Member]
Assets:
Total Other Temporary Investments	0	[10]			0	[10]
Mutual Funds Equity [Member] | Fair Value Inputs Other [Member]
Assets:
Total Other Temporary Investments	0	[10]			0	[10]
Cash and Cash Equivalents [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	19,000,000	[11]			18,000,000	[11]
Gross Unrealized Gains	0				0
Other-Than-Temporary Impairments	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	19,000,000	[11]			18,000,000	[11]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	19,000,000	[11]			18,000,000	[11]
Cash and Cash Equivalents [Member] | Level 1 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0	[11]			0	[11]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0	[11]			0	[11]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0	[11]			0	[11]
Cash and Cash Equivalents [Member] | Level 2 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	10,000,000	[11]			5,000,000	[11]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	10,000,000	[11]			5,000,000	[11]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	10,000,000	[11]			5,000,000	[11]
Cash and Cash Equivalents [Member] | Level 3 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0	[11]			0	[11]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0	[11]			0	[11]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0	[11]			0	[11]
Cash and Cash Equivalents [Member] | Fair Value Inputs Other [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	9,000,000	[11]			13,000,000	[11]
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	9,000,000	[11]			13,000,000	[11]
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	9,000,000	[11]			13,000,000	[11]
US Government Agencies Debt Securities [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	548,000,000				544,000,000
Gross Unrealized Gains	49,000,000				61,000,000
Other-Than-Temporary Impairments	(1,000,000)				(1,000,000)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	548,000,000				544,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	548,000,000				544,000,000
US Government Agencies Debt Securities [Member] | Level 1 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
US Government Agencies Debt Securities [Member] | Level 2 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	548,000,000				544,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	548,000,000				544,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	548,000,000				544,000,000
US Government Agencies Debt Securities [Member] | Level 3 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
US Government Agencies Debt Securities [Member] | Fair Value Inputs Other [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
Corporate Debt [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	52,000,000				54,000,000
Gross Unrealized Gains	5,000,000				5,000,000
Other-Than-Temporary Impairments	(1,000,000)				(2,000,000)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	52,000,000				54,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	52,000,000				54,000,000
Corporate Debt [Member] | Level 1 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
Corporate Debt [Member] | Level 2 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	52,000,000				54,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	52,000,000				54,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	52,000,000				54,000,000
Corporate Debt [Member] | Level 3 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
Corporate Debt [Member] | Fair Value Inputs Other [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
State and Local Jurisdiction [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	323,000,000				330,000,000
Gross Unrealized Gains	0				0
Other-Than-Temporary Impairments	(1,000,000)				(2,000,000)
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	323,000,000				330,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	323,000,000				330,000,000
State and Local Jurisdiction [Member] | Level 1 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
State and Local Jurisdiction [Member] | Level 2 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	323,000,000				330,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	323,000,000				330,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	323,000,000				330,000,000
State and Local Jurisdiction [Member] | Level 3 [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
State and Local Jurisdiction [Member] | Fair Value Inputs Other [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	0				0
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	0				0
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	0				0
Dedesignated Risk Management Contracts [Member]
Risk Management Assets
Risk Management Assets	25,000,000	[12]			28,000,000	[12]
Dedesignated Risk Management Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	0	[12]			0	[12]
Dedesignated Risk Management Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	0	[12]			0	[12]
Dedesignated Risk Management Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	0	[12]			0	[12]
Dedesignated Risk Management Contracts [Member] | Fair Value Inputs Other [Member]
Risk Management Assets
Risk Management Assets	25,000,000	[12]			28,000,000	[12]
Other Temporary Investments [Member]
Other Temporary Investments
Cost	212,000,000				291,000,000
Gross Unrealized Gains	5,000,000				3,000,000
Gross Unrealized Losses	0				0
2012 [Member] | Level 1 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	3,000,000				3,000,000
2012 [Member] | Level 2 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	4,000,000				21,000,000
2012 [Member] | Level 3 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	3,000,000				(19,000,000)
2013 - 2015 [Member] | Level 1 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	12,000,000				7,000,000
2013 - 2015 [Member] | Level 2 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	49,000,000				50,000,000
2013 - 2015 [Member] | Level 3 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	46,000,000				44,000,000
2016 - 2017 [Member] | Level 2 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	18,000,000				11,000,000
2016 - 2017 [Member] | Level 3 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	18,000,000				18,000,000
2016 - 2018 [Member] | Level 1 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	(7,000,000)				(6,000,000)
2018 - 2030 [Member] | Level 2 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	7,000,000				8,000,000
2018 - 2030 [Member] | Level 3 [Member]
Fair Value Measurements (Textuals) [Abstract]
Maturity of Net Fair Value of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities	24,000,000				26,000,000
Within 1 Year [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	39,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	39,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	39,000,000
1 year - 5 years [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	322,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	322,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	322,000,000
5 years - 10 years [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	341,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	341,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	341,000,000
After 10 years [Member]
Nuclear Trust Fund Investments [Abstract]
Estimated Fair Value	221,000,000
Contractual Maturities, Fair Value of Debt Securities
Contractual Maturities, Fair Value of Debt Securities	221,000,000
Spent Nuclear Fuel and Decommissioning Trusts
Spent Nuclear Fuel and Decommissioning Trusts	221,000,000
Risk Management Commodity Contracts [Member]
Risk Management Assets
Risk Management Assets	616,000,000	[13],[14]			548,000,000	[13],[15]
Liabilities:
Risk Management Liabilities	354,000,000	[13],[14]			278,000,000	[13],[15]
Risk Management Commodity Contracts [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	61,000,000	[13],[14]			47,000,000	[13],[15]
Liabilities:
Risk Management Liabilities	53,000,000	[13],[14]			43,000,000	[13],[15]
Risk Management Commodity Contracts [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	1,821,000,000	[13],[14]			1,299,000,000	[13],[15]
Liabilities:
Risk Management Liabilities	1,743,000,000	[13],[14]			1,209,000,000	[13],[15]
Risk Management Commodity Contracts [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	169,000,000	[13],[14]			147,000,000	[13],[15]
Liabilities:
Risk Management Liabilities	78,000,000	[13],[14]			78,000,000	[13],[15]
Risk Management Commodity Contracts [Member] | Fair Value Inputs Other [Member]
Risk Management Assets
Risk Management Assets	(1,435,000,000)	[13],[14]			(945,000,000)	[13],[15]
Liabilities:
Risk Management Liabilities	(1,520,000,000)	[13],[14]			(1,052,000,000)	[13],[15]
Commodity Hedges [Member]
Risk Management Assets
Risk Management Assets	29,000,000	[13]			20,000,000	[13]
Liabilities:
Risk Management Liabilities	55,000,000	[13]			25,000,000	[13]
Commodity Hedges [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	17,000,000	[13]			15,000,000	[13]
Liabilities:
Risk Management Liabilities	0	[13]			0	[13]
Commodity Hedges [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	43,000,000	[13]			23,000,000	[13]
Liabilities:
Risk Management Liabilities	87,000,000	[13]			43,000,000	[13]
Commodity Hedges [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	1,000,000	[13]			0	[13]
Liabilities:
Risk Management Liabilities	0	[13]			0	[13]
Commodity Hedges [Member] | Fair Value Inputs Other [Member]
Risk Management Assets
Risk Management Assets	(32,000,000)	[13]			(18,000,000)	[13]
Liabilities:
Risk Management Liabilities	(32,000,000)	[13]			(18,000,000)	[13]
Interest Rate Foreign Currency Hedges [Member]
Liabilities:
Risk Management Liabilities	15,000,000				42,000,000
Interest Rate Foreign Currency Hedges [Member] | Level 1 [Member]
Liabilities:
Risk Management Liabilities	0				0
Interest Rate Foreign Currency Hedges [Member] | Level 2 [Member]
Liabilities:
Risk Management Liabilities	15,000,000				42,000,000
Interest Rate Foreign Currency Hedges [Member] | Level 3 [Member]
Liabilities:
Risk Management Liabilities	0				0
Interest Rate Foreign Currency Hedges [Member] | Fair Value Inputs Other [Member]
Liabilities:
Risk Management Liabilities	0				0
Fair Value Hedges [Member]
Risk Management Assets
Risk Management Assets	1,000,000
Fair Value Hedges [Member] | Level 1 [Member]
Risk Management Assets
Risk Management Assets	0
Fair Value Hedges [Member] | Level 2 [Member]
Risk Management Assets
Risk Management Assets	1,000,000
Fair Value Hedges [Member] | Level 3 [Member]
Risk Management Assets
Risk Management Assets	0
Fair Value Hedges [Member] | Fair Value Inputs Other [Member]
Risk Management Assets
Risk Management Assets	$ 0

[1] Amounts in ''Other'' column primarily represent cash deposits in bank accounts with financial institutions or with third parties. Level 1 amounts primarily represent investments in money market funds.

[2] Included in revenues on our condensed statements of income.

[3] Represents the change in fair value between the beginning of the reporting period and the settlement of the risk management commodity contract.

[4] Represents the settlement of risk management commodity contracts for the reporting period.

[5] Represents existing assets or liabilities that were previously categorized as Level 2.

[6] Transfers are recognized based on their value at the beginning of the reporting period that the transfer occurred.

[7] Represents existing assets or liabilities that were previously categorized as Level 3.

[8] Relates to the net gains (losses) of those contracts that are not reflected on our condensed statements of income. These net gains (losses) are recorded as regulatory liabilities/assets

[9] Primarily represents amounts held for the repayment of debt.

[10] Amounts represent publicly traded equity securities and equity-based mutual funds.

[11] Amounts in ''Other'' column primarily represent accrued interest receivables from financial institutions. Level 2 amounts primarily represent investments in money market funds.

[12] Represents contracts that were originally MTM but were subsequently elected as normal under the accounting guidance for ''Derivatives and Hedging.'' At the time of the normal election, the MTM value was frozen and no longer fair valued. This MTM value will be amortized into revenues over the remaining life of the contracts.

[13] Amounts in ''Other'' column primarily represent counterparty netting of risk management and hedging contracts and associated cash collateral under the accounting guidance for ''Derivatives and Hedging.''

[14] The March 31, 2012 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), is as follows: Level 1 matures $3 million in 2012, $12 million in periods 2013-2015 and ($7) million in periods 2016-2018; Level 2 matures $4 million in 2012, $49 million in periods 2013-2015, $18 million in periods 2016-2017 and $7 million in periods 2018-2030; Level 3 matures $3 million in 2012, $46 million in periods 2013-2015, $18 million in periods 2016-2017 and $24 million in periods 2018-2030. Risk management commodity contracts are substantially comprised of power contracts.

[15] The December 31, 2011 maturity of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), is as follows: Level 1 matures $3 million in 2012, $7 million in periods 2013-2015 and ($6) million in periods 2016-2018; Level 2 matures $21 million in 2012, $50 million in periods 2013-2015, $11 million in periods 2016-2017 and $8 million in periods 2018-2030; Level 3 matures ($19) million in 2012, $44 million in periods 2013-2015, $18 million in periods 2016-2017 and $26 million in periods 2018-2030. Risk management commodity contracts are substantially comprised of power contracts.