Leases Leases (Schedule of Rent Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leases, Rent Expense, Net	$ 47.8	$ 53.1	$ 44.4
Entergy Arkansas [Member]
Operating Leases, Rent Expense, Net	6.2	7.5	8.0
Entergy Louisiana [Member]
Operating Leases, Rent Expense, Net	20.2	23.0	17.8
Entergy Mississippi [Member]
Operating Leases, Rent Expense, Net	4.6	5.6	4.0
Entergy New Orleans [Member]
Operating Leases, Rent Expense, Net	2.5	2.5	0.9
Entergy Texas [Member]
Operating Leases, Rent Expense, Net	3.1	3.4	2.8
System Energy [Member]
Operating Leases, Rent Expense, Net	$ 1.9	$ 2.2	$ 1.6