Property, Plant, And Equipment (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended																	1 Months Ended
	Mar. 31, 2012	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Entergy Arkansas [Member]	Dec. 31, 2011 Entergy Arkansas [Member]	Sep. 30, 2012 Entergy Gulf States Louisiana [Member]	Dec. 31, 2011 Entergy Gulf States Louisiana [Member]	Sep. 30, 2012 Entergy Louisiana [Member]	Dec. 31, 2011 Entergy Louisiana [Member]	Sep. 30, 2012 Entergy Mississippi [Member]	Dec. 31, 2011 Entergy Mississippi [Member]	Sep. 30, 2012 Entergy New Orleans	Dec. 31, 2011 Entergy New Orleans	Sep. 30, 2012 Entergy Texas [Member]	Dec. 31, 2011 Entergy Texas [Member]	Sep. 30, 2012 System Energy [Member]	Dec. 31, 2011 System Energy [Member]	Mar. 31, 2011 Vermont Yankee [Member]
Construction expenditures in accounts payable		$ 315.1	$ 171.2	$ 12.4	$ 14.1	$ 47.2	$ 13.7	$ 159.5	$ 27.0	$ 15.0	$ 4.3	$ 15.3	$ 3.6	$ 3.5	$ 4.3	$ 24.8	$ 32.9
Operating license renewal, years																		20
Estimated Fair Value of Nuclear Plant	162.0
Carrying Value of Nuclear Plant	517.5
Asset Impairment Charges	355.5
After-Tax Asset Impairment Charge	$ 223.5