Asset Retirement Obligations (Difference Between Estimated Incurred Removal Costs And Estimated Removal Costs Recovered In Rates) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Oct. 31, 2015	Dec. 31, 2014
Asset Retirement Obligations [Line Items]
Regulatory Liabilities		$ (107.0)
Entergy Arkansas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 85.7		$ 59.0
Entergy Louisiana [Member]
Asset Retirement Obligations [Line Items]
Regulatory Liabilities	(68.3)		(82.6)
Entergy Mississippi [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	77.5		76.3
Entergy New Orleans [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	29.4		35.2
Entergy Texas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	25.8		18.9
System Energy [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 54.8		$ 55.7