Asset Retirement Obligations (Difference Between Estimated Incurred Removal Costs And Estimated Removal Costs Recovered In Rates) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015	Oct. 31, 2015
Asset Retirement Obligations [Line Items]
Regulatory Liabilities				$ (107.0)
Entergy Arkansas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 128.5		$ 85.7
Entergy Louisiana [Member]
Asset Retirement Obligations [Line Items]
Regulatory Liabilities	(53.9)	$ (16.1)	(68.3)
Entergy Mississippi [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	82.0		77.5
Entergy New Orleans [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	40.1		29.4
Entergy Texas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	33.5		25.8
System Energy [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 69.7		$ 54.8