Leases (Rent Expenses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Rent Expense	$ 44.4	$ 63.9	$ 59.0
Entergy Arkansas [Member]
Rent Expense	8.0	13.6	12.0
Entergy Louisiana [Member]
Rent Expense	17.8	21.8	20.7
Entergy Mississippi [Member]
Rent Expense	4.0	5.4	4.3
Entergy New Orleans [Member]
Rent Expense	0.9	1.6	1.2
Entergy Texas [Member]
Rent Expense	2.8	4.0	3.8
System Energy [Member]
Rent Expense	$ 1.6	$ 2.9	$ 2.0