Risk Management and Fair Values (Schedules Of Valuation Techniques) (Details) - Parent Company [Member] $ in Millions	Mar. 31, 2016 USD ($)
Range From Average Percentage for Electricity Options	30.00%
Range from Average Percentage for Fair Value of Electricity Swaps	3.00%
Effect of Significant Unobservable Inputs on Fair Value of Electricity Swaps	$ 7
Effect of Significant Unobservable Inputs on Fair Value of Electricity Options	10
Fair Value of Electricity Options	34
Fair Value of Electricity Swaps	$ 149

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

No definition available.

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

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

Name:	dei_LegalEntityAxis=us-gaap_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: