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	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of changes in the net assets (liabilities) for the fair value of derivatives classified as Level 3 in the fair value hierarchy [Roll Forward]
Included in earnings	$ (9.2)	$ (3.5)	$ 0.9
Issuances of financial transmission rights	0.0	0.0	0.0
Financial Transmission Rights (FTRs) [Member]
Reconciliation of changes in the net assets (liabilities) for the fair value of derivatives classified as Level 3 in the fair value hierarchy [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	0.0	0.0	0.0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included as Regulatory Liability/Asset	54.0	80.0	76.0
Issuances of financial transmission rights	35.0	46.0	62.0
Gains (losses) included as a regulatory liability/asset	0.0		1.0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		(1.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(94.0)	(131.0)	(139.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	10.0	15.0	21.0	$ 21.0
Electricity Futures Forwards Swaps And Options [Member]
Reconciliation of changes in the net assets (liabilities) for the fair value of derivatives classified as Level 3 in the fair value hierarchy [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	232.0		44.0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		(40.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included as Regulatory Liability/Asset	0.0	0.0	0.0
Gains (losses) included as a regulatory liability/asset	12.0	2.0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings			(3.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(95.0)		(111.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements		(72.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	118.0			$ 5.0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value		(31.0)	(65.0)
Entergy Arkansas [Member]
Reconciliation of changes in the net assets (liabilities) for the fair value of derivatives classified as Level 3 in the fair value hierarchy [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included as Regulatory Liability/Asset	12.6	13.9
Issuances of financial transmission rights	9.6	11.8
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(22.3)	(25.3)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	3.3	3.4	3.0
Entergy Louisiana [Member]
Reconciliation of changes in the net assets (liabilities) for the fair value of derivatives classified as Level 3 in the fair value hierarchy [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included as Regulatory Liability/Asset	24.2	50.8
Issuances of financial transmission rights	18.7	20.0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(46.7)	(72.7)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	4.5	8.3	10.2
Entergy Mississippi [Member]
Reconciliation of changes in the net assets (liabilities) for the fair value of derivatives classified as Level 3 in the fair value hierarchy [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included as Regulatory Liability/Asset	1.5	21.9
Issuances of financial transmission rights	3.9	4.5
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(6.8)	(26.3)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0.8	2.2	2.1
Entergy New Orleans [Member]
Reconciliation of changes in the net assets (liabilities) for the fair value of derivatives classified as Level 3 in the fair value hierarchy [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included as Regulatory Liability/Asset	(1.0)	9.2
Issuances of financial transmission rights	2.7	3.7
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(2.7)	(13.8)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0.3	1.3	2.2
Entergy Texas [Member]
Reconciliation of changes in the net assets (liabilities) for the fair value of derivatives classified as Level 3 in the fair value hierarchy [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included as Regulatory Liability/Asset	17.0	(16.0)
Issuances of financial transmission rights	0.1	6.1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(15.7)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements		(6.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 0.9		$ 3.4
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value		$ (0.5)