Income Taxes (Summary Of Accrued Interest And Penalties Related To Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accrued income tax interest and penalties	$ 30.0	$ 27.0	$ 127.0
Entergy Arkansas [Member]
Accrued income tax interest and penalties	1.4	1.3	17.0
Entergy Louisiana [Member]
Accrued income tax interest and penalties	8.4	9.3	22.2
Entergy Mississippi [Member]
Accrued income tax interest and penalties	0.8	0.4	2.8
Entergy New Orleans [Member]
Accrued income tax interest and penalties	1.5	1.8	1.3
Entergy Texas [Member]
Accrued income tax interest and penalties	1.2	1.2	1.0
System Energy [Member]
Accrued income tax interest and penalties	$ 3.7	$ 0.7	$ 23.8