Property, Plant, And Equipment (Narrative) (USD $) In Millions, unless otherwise specified	3 Months Ended									1 Months Ended
	Mar. 31, 2012	Jun. 30, 2012	Jun. 30, 2012 Entergy Arkansas [Member]	Jun. 30, 2012 Entergy Gulf States Louisiana [Member]	Jun. 30, 2012 Entergy Louisiana [Member]	Jun. 30, 2012 Entergy Mississippi [Member]	Jun. 30, 2012 Entergy New Orleans	Jun. 30, 2012 Entergy Texas [Member]	Jun. 30, 2012 System Energy [Member]	Mar. 31, 2011 Vermont Yankee [Member]
Construction expenditures in accounts payable		$ 159.7	$ 7.2	$ 15.9	$ 28.0	$ 1.2	$ 0.2	$ 0.6	$ 76.7
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