Income Taxes (Summary Of Unrecognized Benefits That Would Affect Effective Income Tax Rate) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Unrecognized tax benefits that would impact effective income tax rate	$ 516.0	$ 176.0	$ 203.0
Entergy Arkansas [Member]
Unrecognized tax benefits that would impact effective income tax rate	2.6	0.6	0.6
Entergy Gulf States Louisiana [Member]
Unrecognized tax benefits that would impact effective income tax rate	91.9	44.0	44.0
Entergy Louisiana [Member]
Unrecognized tax benefits that would impact effective income tax rate	175.4	87.9	92.4
Entergy Mississippi [Member]
Unrecognized tax benefits that would impact effective income tax rate	3.9	3.9	3.9
Entergy New Orleans [Member]
Unrecognized tax benefits that would impact effective income tax rate	50.7	0	0
Entergy Texas [Member]
Unrecognized tax benefits that would impact effective income tax rate	10.5	10.1	8.6
System Energy [Member]
Unrecognized tax benefits that would impact effective income tax rate	$ 3.7	$ 3.3	$ 3.5