Regulatory Matters (Schedule Of Regulatory Assets And Regulatory Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	$ 2,196		$ 1,915
Regulatory Liabilities	526		528
Pension And OPEB Costs [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	1,037	[1]	848	[1]
Securitized Stranded Costs [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	481	[1]	559	[1]
Deferred Income Taxes [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	145		139
Deferred Energy Supply Costs [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	124	[1]	61	[1]
Recoverable Meter-Related Costs [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	112	[1]	44	[1]
Deferred Debt Extinguishment Costs [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	57	[1]	61	[1]
Recoverable Workers Compensation And Long-Term Disability Costs [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	34		28
Blueprint For The Future [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	30		16
Deferred Losses On Gas Derivatives [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	17		31
Other Regulatory Assets [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Assets	159		128
Asset Removal Costs [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Liabilities	388		361
Deferred Income Taxes [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Liabilities	48		50
Deferred Energy Supply Costs [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Liabilities	33		35
Excess Depreciation Reserve [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Liabilities	26		42
Other Regulatory Liabilities [Member]
Regulatory Assets and Regulatory Liabilities [Line Items]
Regulatory Liabilities	$ 31		$ 40

[1] A return is generally earned on these deferrals.