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, 2012	Dec. 31, 2011
Entergy Arkansas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Liabilities	$ (12.2)	$ (16.4)
Entergy Gulf States Louisiana [Member]
Asset Retirement Obligations [Line Items]
Regulatory Liabilities	(22.0)	(30.3)
Entergy Louisiana [Member]
Asset Retirement Obligations [Line Items]
Regulatory Liabilities	(9.2)	(62.6)
Entergy Mississippi [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	57.4	48.5
Entergy New Orleans [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	29.9	16.3
Entergy Texas [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	11.5	4.5
System Energy [Member]
Asset Retirement Obligations [Line Items]
Regulatory Assets	$ 56.8	$ 11.8