Income Taxes (Summary Of Accrued Interest And Penalties Related To Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accrued income tax interest and penalties	$ 44.0	$ 48.0	$ 44.0
Entergy Arkansas [Member]
Accrued income tax interest and penalties	2.3	3.1	1.7
Entergy Louisiana [Member]
Accrued income tax interest and penalties	3.4	14.2	17.9
Entergy Mississippi [Member]
Accrued income tax interest and penalties	1.9	1.7	1.2
Entergy New Orleans [Member]
Accrued income tax interest and penalties	3.9	4.7	2.7
Entergy Texas [Member]
Accrued income tax interest and penalties	0.9	1.1	0.9
System Energy [Member]
Accrued income tax interest and penalties	$ 11.9	$ 14.5	$ 13.2