Income Taxes (Summary Of Accrued Interest And Penalties Related To Unrecognized Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accrued income tax interest and penalties	$ 146.3	$ 99.0	$ 45.0
Entergy Arkansas [Member]
Accrued income tax interest and penalties	21.8	11.4
Entergy Gulf States Louisiana [Member]
Accrued income tax interest and penalties	33.1	14.4	9.7
Entergy Louisiana [Member]
Accrued income tax interest and penalties	0.9	0.8	3.3
Entergy Mississippi [Member]
Accrued income tax interest and penalties	2.4	1.7	1.6
Entergy New Orleans [Member]
Accrued income tax interest and penalties	0.1	2.4
Entergy Texas [Member]
Accrued income tax interest and penalties	0.7	0.1	0.1
System Energy [Member]
Accrued income tax interest and penalties	$ 33.2	$ 18.5	$ 8.2