Property, Plant, And Equipment (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Construction expenditures in accounts payable	$ 219.0	$ 253.0
Entergy Arkansas [Member]
Construction expenditures in accounts payable	28.6	40.9
Entergy Louisiana [Member]
Construction expenditures in accounts payable	95.5	114.8
Entergy Mississippi [Member]
Construction expenditures in accounts payable	7.2	11.5
Entergy New Orleans [Member]
Construction expenditures in accounts payable	0.6	2.3
Entergy Texas [Member]
Construction expenditures in accounts payable	18.9	9.3
System Energy [Member]
Construction expenditures in accounts payable	$ 26.9	$ 6.2