Property, Plant, And Equipment (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Construction expenditures in accounts payable	$ 141.9	$ 267.0
Entergy Arkansas [Member]
Construction expenditures in accounts payable	31.9	56.3
Entergy Gulf States Louisiana [Member]
Construction expenditures in accounts payable	17.3	9.7
Entergy Louisiana [Member]
Construction expenditures in accounts payable	34.5	110.4
Entergy Mississippi [Member]
Construction expenditures in accounts payable	1.8	4.8
Entergy New Orleans
Construction expenditures in accounts payable	2.7	1.9
Entergy Texas [Member]
Construction expenditures in accounts payable	1.1	8.6
System Energy [Member]
Construction expenditures in accounts payable	$ 5.9	$ 13.5