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, 2017	Dec. 31, 2016	Dec. 31, 2015
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	$ 0.9	$ 0.0	$ 3.0
Fixed 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]
Balance as of Beginning of Period	21.0	23.0	47.0
Total gains (losses) for the period (a)	1.0	0.0	(1.0)
Included in other comprehensive income	0.0	0.0	0.0
Issuances of financial transmission rights	62.0	55.0	80.0
Gains (losses) included as a regulatory liability/asset	76.0	68.0	63.0
Purchases	0.0	0.0	0.0
Settlements	(139.0)	(125.0)	(166.0)
Balance as of End of Period	21.0	21.0	23.0
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]
Balance as of Beginning of Period	5.0	189.0	215.0
Total gains (losses) for the period (a)	(3.0)	(10.0)	(20.0)
Included in other comprehensive income	44.0	135.0	254.0
Issuances of financial transmission rights	0.0	0.0	0.0
Gains (losses) included as a regulatory liability/asset	0.0	0.0	0.0
Purchases	0.0	0.0	15.0
Settlements	(111.0)	(309.0)	(275.0)
Balance as of End of Period	(65.0)	5.0	189.0
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]
Balance as of Beginning of Period	5.4	7.9
Issuances of financial transmission rights	8.9	18.8
Gains (losses) included as a regulatory liability/asset	30.4	1.9
Settlements	(41.7)	(23.2)
Balance as of End of Period	3.0	5.4	7.9
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]
Balance as of Beginning of Period	8.5	8.5
Issuances of financial transmission rights	31.0	18.1
Gains (losses) included as a regulatory liability/asset	16.5	51.6
Settlements	(45.8)	(69.7)
Balance as of End of Period	10.2	8.5	8.5
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]
Balance as of Beginning of Period	3.2	2.4
Issuances of financial transmission rights	9.6	5.9
Gains (losses) included as a regulatory liability/asset	8.2	11.5
Settlements	(18.9)	(16.6)
Balance as of End of Period	2.1	3.2	2.4
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]
Balance as of Beginning of Period	1.1	1.5
Issuances of financial transmission rights	5.0	2.8
Gains (losses) included as a regulatory liability/asset	5.2	0.9
Settlements	(9.1)	(4.1)
Balance as of End of Period	2.2	1.1	1.5
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]
Balance as of Beginning of Period	3.1	2.2
Issuances of financial transmission rights	7.1	9.3
Gains (losses) included as a regulatory liability/asset	15.5	1.8
Settlements	(22.3)	(10.2)
Balance as of End of Period	$ 3.4	$ 3.1	$ 2.2