Asset Retirement Obligations (Difference Between Estimated Incurred Removal Costs And Estimated Removal Costs Recovered In Rates) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Entergy Arkansas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 168.9	$ 138.3
Entergy Louisiana [Member]
Asset Retirement Obligations [Line Items]
Regulatory Liabilities	(2.4)	(18.8)
Entergy Mississippi [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	80.8	63.5
Entergy New Orleans [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	52.9	49.3
Entergy Texas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	42.5	50.9
System Energy [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 75.9	76.4
Regulatory Liabilities		$ (55.6)