Property, Plant, And Equipment (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Construction expenditures in accounts payable	$ 161.9	$ 267.0
Entergy Arkansas [Member]
Construction expenditures in accounts payable	12.0	56.3
Entergy Gulf States Louisiana [Member]
Construction expenditures in accounts payable	27.1	9.7
Entergy Louisiana [Member]
Construction expenditures in accounts payable	54.1	110.4
Entergy Mississippi [Member]
Construction expenditures in accounts payable	1.7	4.8
Entergy New Orleans
Construction expenditures in accounts payable	1.6	1.9
Entergy Texas [Member]
Construction expenditures in accounts payable	3.6	8.6
System Energy [Member]
Construction expenditures in accounts payable	$ 6.0	$ 13.5