Risk Management and Fair Values (Derivative Instruments Not Designated As Hedging Instruments On The Consolidated Statements Of Income) (Details) (Imported) (Not Designated As Hedging Instrument [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Competitive Businesses Operating Revenues [Member] | Electricity Swaps And Options [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recognized in AOCI	$ (2)	$ (4)		$ 6
Amount of gain (loss) recorded in income	3.0	4.0	1.0	6.0
Fuel, Fuel Related Expenses And Gas Purchased For Resale [Member] | Swap [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recognized in AOCI
Amount of gain (loss) recorded in income	16.0	(9.0)	(35.0)	(12.0)
Entergy Gulf States Louisiana [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recorded in income	4.7	(2.3)	(10.3)	(4.2)
Entergy Louisiana [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recorded in income	6.5	(3.9)	(14.2)	(5.0)
Entergy Mississippi [Member] | Fuel, Fuel Related Expenses And Gas Purchased For Resale [Member] | Natural Gas Swaps [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recorded in income	4.5	(2.8)	(8.9)	(2.5)
Entergy New Orleans | Fuel, Fuel Related Expenses And Gas Purchased For Resale [Member] | Swap [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recorded in income		$ (0.1)	$ (1.5)	$ (0.9)