Income Taxes (Summary Of Unrecognized Benefits That Would Affect Effective Income Tax Rate) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unrecognized tax benefits that would impact effective income tax rate	$ 2,421.0	$ 2,161.0	$ 1,462.0
Entergy Arkansas [Member]
Unrecognized tax benefits that would impact effective income tax rate	203.3	85.4	2.6
Entergy Louisiana [Member]
Unrecognized tax benefits that would impact effective income tax rate	556.3	594.0	575.8
Entergy Mississippi [Member]
Unrecognized tax benefits that would impact effective income tax rate	1.9	1.5	0.0
Entergy New Orleans [Member]
Unrecognized tax benefits that would impact effective income tax rate	242.7	246.2	31.7
Entergy Texas [Member]
Unrecognized tax benefits that would impact effective income tax rate	5.7	5.1	4.4
System Energy [Member]
Unrecognized tax benefits that would impact effective income tax rate	$ 0.0	$ 0.0	$ 0.0