Income Taxes (Summary Of Unrecognized Benefits That Would Affect Effective Income Tax Rate) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrecognized tax benefits that would impact effective income tax rate	$ 2,208.0	$ 2,421.0	$ 2,161.0
Entergy Arkansas [Member]
Unrecognized tax benefits that would impact effective income tax rate	259.3	203.3	85.4
Entergy Louisiana [Member]
Unrecognized tax benefits that would impact effective income tax rate	63.8	556.3	594.0
Entergy Mississippi [Member]
Unrecognized tax benefits that would impact effective income tax rate	50.7	1.9	1.5
Entergy New Orleans [Member]
Unrecognized tax benefits that would impact effective income tax rate	203.5	242.7	246.2
Entergy Texas [Member]
Unrecognized tax benefits that would impact effective income tax rate	6.1	5.7	5.1
System Energy [Member]
Unrecognized tax benefits that would impact effective income tax rate	$ 0.5	$ 0.0	$ 0.0