Leases (Rent Expenses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Rent Expense	$ 63.9	$ 59.0	$ 63.7
Entergy Arkansas [Member]
Rent Expense	13.6	12.0	12.0
Entergy Louisiana [Member]
Rent Expense	21.8	20.7	21.0
Entergy Mississippi [Member]
Rent Expense	5.4	4.3	4.6
Entergy New Orleans [Member]
Rent Expense	1.6	1.2	1.3
Entergy Texas [Member]
Rent Expense	4.0	3.8	4.1
System Energy [Member]
Rent Expense	$ 2.9	$ 2.0	$ 2.5