Asset Retirement Obligations (Difference Between Estimated Incurred Removal Costs And Estimated Removal Costs Recovered In Rates) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Entergy Arkansas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 212.6	$ 168.9
Entergy Louisiana [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	302.5
Net regulatory liability related to sale and leaseback transaction		(2.4)
Entergy Mississippi [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	107.3	80.8
Entergy New Orleans [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	63.2	52.9
Entergy Texas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	115.3	42.5
System Energy [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 92.9	$ 75.9