Leases (Rent Expenses) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Rent Expense	$ 69.9	$ 75.3	$ 80.8
Entergy Arkansas [Member]
Rent Expense	12.6	13.4	13.0
Entergy Gulf States Louisiana [Member]
Rent Expense	11.9	12.2	12.5
Entergy Louisiana [Member]
Rent Expense	11.2	12.2	11.7
Entergy Mississippi [Member]
Rent Expense	5.5	5.2	5.5
Entergy New Orleans [Member]
Rent Expense	1.5	1.7	1.7
Entergy Texas [Member]
Rent Expense	6.4	8.4	7.4
System Energy [Member]
Rent Expense	$ 1.5	$ 1.6	$ 1.4