Risk Management and Fair Values (Reconciliation Of Changes In The Net Assets (Liabilities) For The Fair Value Of Derivatives Classified As Level 3 In The Fair Value Hierarchy) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of Fixed Transmission Rights			$ 0.0	$ 0.0
Electricity Swaps And Options [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset and Liability, Realized Gain (Loss) Included In Earnings	$ 2.0	$ 6.0	6.0	(3.0)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	38.0	66.0	5.0	189.0
Unrealized losses included in OCI	43.0	70.0	136.0	156.0
Included as a regulatory liability/asset	0.0	0.0	0.0	0.0
Settlements	(23.0)	(47.0)	(87.0)	(247.0)
Balance as of September 30,	60.0	95.0	60.0	95.0
Fixed Transmission Rights (FTRs) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset and Liability, Realized Gain (Loss) Included In Earnings	0.0	0.0	1.0	0.0
Issuance of Fixed Transmission Rights			62.0	55.0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	57.0	46.0	21.0	23.0
Unrealized losses included in OCI	0.0	0.0	0.0	0.0
Included as a regulatory liability/asset	8.0	22.0	56.0	49.0
Settlements	(28.0)	(37.0)	(103.0)	(96.0)
Balance as of September 30,	37.0	31.0	37.0	31.0
Fixed Transmission Rights (FTRs) [Member] | Entergy Arkansas [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of Fixed Transmission Rights			8.9	18.8
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	8.3	14.0	5.4	7.9
Unrealized gains included as a regulatory liability/asset	0.3	1.2	9.4	1.7
Settlements	(4.2)	(7.1)	(19.3)	(20.3)
Balance as of September 30,	4.4	8.1	4.4	8.1
Fixed Transmission Rights (FTRs) [Member] | Entergy Louisiana [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of Fixed Transmission Rights			31.0	18.1
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	28.3	16.2	8.5	8.5
Unrealized gains included as a regulatory liability/asset	(0.1)	16.6	18.2	38.3
Settlements	(9.4)	(20.4)	(38.9)	(52.5)
Balance as of September 30,	18.8	12.4	18.8	12.4
Fixed Transmission Rights (FTRs) [Member] | Entergy Mississippi [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of Fixed Transmission Rights			9.6	5.9
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	9.1	5.6	3.2	2.4
Unrealized gains included as a regulatory liability/asset	1.1	5.1	9.0	6.8
Settlements	(4.7)	(6.7)	(16.3)	(11.1)
Balance as of September 30,	5.5	4.0	5.5	4.0
Fixed Transmission Rights (FTRs) [Member] | Entergy New Orleans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of Fixed Transmission Rights			5.0	2.8
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	5.2	2.0	1.1	1.5
Unrealized gains included as a regulatory liability/asset	0.2	0.5	5.1	0.1
Settlements	(1.9)	(0.9)	(7.7)	(2.8)
Balance as of September 30,	3.5	1.6	3.5	1.6
Fixed Transmission Rights (FTRs) [Member] | Entergy Texas [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of Fixed Transmission Rights			7.1	9.3
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at Beginning of Period	5.5	8.0	3.1	2.2
Unrealized gains included as a regulatory liability/asset	6.5	(1.1)	14.0	2.3
Settlements	(7.0)	(1.8)	(19.2)	(8.7)
Balance as of September 30,	$ 5.0	$ 5.1	$ 5.0	$ 5.1