Asset Retirement Obligations (Difference Between Estimated Incurred Removal Costs And Estimated Removal Costs Recovered In Rates) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Entergy Arkansas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 59.0	$ 18.6
Entergy Gulf States Louisiana [Member]
Asset Retirement Obligations [Line Items]
Regulatory Liabilities	(36.9)	(35.3)
Entergy Louisiana [Member]
Asset Retirement Obligations [Line Items]
Regulatory Liabilities	(45.7)	(37.0)
Entergy Mississippi [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	76.3	64.3
Entergy New Orleans [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	35.2	34.9
Entergy Texas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	18.9	15.1
System Energy [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 55.7	$ 56.0