Income Taxes (Summary Of Unrecognized Benefits That Would Affect Effective Income Tax Rate) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2016
Unrecognized tax benefits that would impact effective income tax rate	$ 2,161.0	$ 1,462.0	$ 1,240.0	$ 63.5
Entergy Arkansas [Member]
Unrecognized tax benefits that would impact effective income tax rate	85.4	2.6	3.6
Entergy Louisiana [Member]
Unrecognized tax benefits that would impact effective income tax rate	594.0	575.8	473.3	$ 61.6
Entergy Mississippi [Member]
Unrecognized tax benefits that would impact effective income tax rate	1.5	0.0	0.0
Entergy New Orleans [Member]
Unrecognized tax benefits that would impact effective income tax rate	246.2	31.7	33.6
Entergy Texas [Member]
Unrecognized tax benefits that would impact effective income tax rate	5.1	4.4	7.0
System Energy [Member]
Unrecognized tax benefits that would impact effective income tax rate	$ 0.0	$ 0.0	$ 0.0