Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		Jun. 30, 2015		Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		$ 109		$ 94
Total assets		3,452		3,399
Total liabilities		166		166
Amount primarily related to deferred taxes on appreciation of investment value		350		324
Other Investments				33
Nuclear Decommissioning Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		32		17
Total assets		2,854	[1]	2,745	[2]
Fixed-income securities		1,222		1,130
Global equity securities		1,600		1,598
Price Risk Management Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		232		253
Electricity		227		251
Natural Gas		5		2
Electricity		164		163
Natural Gas		2		3
Rabbi Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		114		114
Fixed-income securities		42		42
Life insurance contracts		72		72
Long-Term Disability Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		4		7
Total assets		143		160
Fixed-income securities		117		128
Global equity securities		22		25
Fair Value Measurements, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		109		94
Total assets		2,415		2,478
Total liabilities		47		47
Other Investments				33
Fair Value Measurements, Level 1 [Member] | Nuclear Decommissioning Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		32		17
Total assets		2,300	[1]	2,343	[2]
Fixed-income securities		681		741
Global equity securities		1,587		1,585
Fair Value Measurements, Level 1 [Member] | Price Risk Management Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		2		1
Electricity		1		0
Natural Gas		1		1
Electricity		47		47
Natural Gas		0		0
Fair Value Measurements, Level 1 [Member] | Rabbi Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		0		0
Fixed-income securities		0		0
Life insurance contracts		0		0
Fair Value Measurements, Level 1 [Member] | Long-Term Disability Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		4		7
Total assets		4		7
Fixed-income securities		0		0
Global equity securities		0		0
Fair Value Measurements, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		0		0
Total assets		819		687
Total liabilities		6		8
Other Investments				0
Fair Value Measurements, Level 2 [Member] | Nuclear Decommissioning Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		0		0
Total assets		554	[1]	402	[2]
Fixed-income securities		541		389
Global equity securities		13		13
Fair Value Measurements, Level 2 [Member] | Price Risk Management Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		12		18
Electricity		8		17
Natural Gas		4		1
Electricity		4		5
Natural Gas		2		3
Fair Value Measurements, Level 2 [Member] | Rabbi Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		114		114
Fixed-income securities		42		42
Life insurance contracts		72		72
Fair Value Measurements, Level 2 [Member] | Long-Term Disability Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		0		0
Total assets		139		153
Fixed-income securities		117		128
Global equity securities		22		25
Fair Value Measurements, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		0		0
Total assets		212		232
Total liabilities		164		163
Other Investments				0
Fair Value Measurements, Level 3 [Member] | Nuclear Decommissioning Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		0		0
Total assets		0	[1]	0	[2]
Fixed-income securities		0		0
Global equity securities		0		0
Fair Value Measurements, Level 3 [Member] | Price Risk Management Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		212		232
Electricity		212		232
Natural Gas		0		0
Electricity		164		163
Natural Gas		0		0
Fair Value Measurements, Level 3 [Member] | Rabbi Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		0		0
Fixed-income securities		0		0
Life insurance contracts		0		0
Fair Value Measurements, Level 3 [Member] | Long-Term Disability Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments		0		0
Total assets		0		0
Fixed-income securities		0		0
Global equity securities		0		0
Netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments	[3]	0		0
Total assets	[3]	6		2
Total liabilities	[3]	(51)		(52)
Other Investments	[3]			0
Netting [Member] | Nuclear Decommissioning Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments	[3]	0		0
Total assets		0	[1]	0	[2],[3]
Fixed-income securities	[3]	0		0
Global equity securities	[3]	0		0
Netting [Member] | Price Risk Management Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[3]	6		2
Electricity	[3]	6		2
Natural Gas	[3]	0		0
Electricity	[3]	(51)		(52)
Natural Gas	[3]	0		0
Netting [Member] | Rabbi Trusts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[3]	0		0
Fixed-income securities	[3]	0		0
Life insurance contracts	[3]	0		0
Netting [Member] | Long-Term Disability Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market investments	[3]	0		0
Total assets	[3]	0		0
Fixed-income securities	[3]	0		0
Global equity securities	[3]	$ 0		$ 0

[1] Represents amount before deducting $350 million, primarily related to deferred taxes on appreciation of investment value.

[2] Represents amount before deducting $324 million, primarily related to deferred taxes on appreciation of investment value.

[3] Includes the effect of the contractual ability to settle contracts under master netting agreements and margin cash collateral.