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, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
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	$ (0.3)	$ (9.2)	$ (3.5)
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	67.0	54.0	80.0
Issuances of financial transmission rights	23.0	35.0	46.0
Gains (losses) included as a regulatory liability/asset	1.0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0.0	(1.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(92.0)	(94.0)	(131.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	9.0	10.0	15.0	$ 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)	77.0	232.0
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
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements			72.0
Gains (losses) included as a regulatory liability/asset	1.0	12.0	2.0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(158.0)	(95.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	38.0	118.0
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	19.6	12.6
Issuances of financial transmission rights	6.5	9.6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(26.7)	(22.3)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	2.7	3.3	3.4
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	6.1	24.2
Issuances of financial transmission rights	13.2	18.7
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(19.6)	(46.7)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	4.2	4.5	8.3
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	1.4	1.5
Issuances of financial transmission rights	1.4	3.9
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(3.0)	(6.8)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0.6	0.8	2.2
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	1.3
Issuances of financial transmission rights	(0.1)	2.7
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included as Regulatory Liability/Asset		(1.0)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(1.4)	(2.7)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0.1	0.3	1.3
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	38.7	17.0
Issuances of financial transmission rights	2.4	0.1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(40.4)	(15.7)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 1.6	$ 0.9
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value			$ (0.5)