Risk Management and Fair Values (Schedules Of Valuation Techniques) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Effect of Significant Unobservable Inputs on Fair Value of Electricity Options	$ 39
Effect of Significant Unobservable Inputs on Fair Value of Electricity Swaps	7
Fair Value of Electricity Options	78
Fair Value of Electricity Swaps	$ 140
Maximum [Member]
Range From Average Percentage for Electricity Options	(9.00%)
Range from Average Percentage for Fair Value of Electricity Swaps	(3.00%)

The effect of significant unobservable inputs on the fair value of electricity options.

No definition available.

Name:	etr_EffectOfSignificantUnobservableInputsOnFairValueOfElectricityOptions
Namespace Prefix:	etr_
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The effect of significant unobservable inputs on the fair value of electricity swaps.

No definition available.

Name:	etr_EffectOfSignificantUnobservableInputsOnFairValueOfElectricitySwaps
Namespace Prefix:	etr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The fair value of electricity options classified as Level 3 in the fair value hierarchy.

No definition available.

Name:	etr_FairValueOfElectricityOptions
Namespace Prefix:	etr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The fair value of electricity swaps classified as Level 3 in the fair value hierarchy

No definition available.

Name:	etr_FairValueOfElectricitySwaps
Namespace Prefix:	etr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The range from the average percentage used when calculating the fair value of electricity options classified as Level 3 in the fair value hierarchy

No definition available.

Name:	etr_RangeFromAveragePercentageForElectricityOptions
Namespace Prefix:	etr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The range from the average percentage used when calculating the fair value of electricity swaps classified as Level 3 in the fair value hierarchy

No definition available.

Name:	etr_RangeFromAveragePercentageForFairValueOfElectricitySwaps
Namespace Prefix:	etr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant