Risk Management and Fair Values (Derivative Instruments Not Designated As Hedging Instruments On The Consolidated Statements Of Income) (Details) - Not Designated As Hedging Instrument [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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) recognized in AOCI	$ 0.0	$ 0.0	$ 0.0
Amount of gain (loss) recorded in income	(31.0)	11.0	(41.0)
Purchased Power Expense [Member] | Fixed Transmission Rights (FTRs) [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recognized in AOCI	0.0	0.0	0.0
Amount of gain (loss) recorded in income	139.0	125.0	166.0
Competitive Businesses Operating Revenues [Member] | Electricity Futures Forwards 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	0.0	0.0	12.0
Amount of gain (loss) recorded in income	0.0	(11.0)	(19.0)
Entergy Louisiana [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	(25.4)	8.4	(33.2)
Entergy Louisiana [Member] | Purchased Power Expense [Member] | Fixed Transmission Rights (FTRs) [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recorded in income	45.8	69.7	55.4
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	(5.2)	3.1	(6.1)
Entergy Mississippi [Member] | Purchased Power Expense [Member] | Fixed Transmission Rights (FTRs) [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recorded in income	18.9	16.6	16.5
Entergy New Orleans [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	(0.3)	(0.4)	(1.4)
Entergy New Orleans [Member] | Purchased Power Expense [Member] | Fixed Transmission Rights (FTRs) [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recorded in income	9.1	4.1	8.5
Entergy Arkansas [Member] | Purchased Power Expense [Member] | Fixed Transmission Rights (FTRs) [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recorded in income	41.7	23.2	68.7
Entergy Texas [Member] | Purchased Power Expense [Member] | Fixed Transmission Rights (FTRs) [Member]
Effect of Derivative instruments not designated as hedging instruments on the consolidated statements of income
Amount of gain (loss) recorded in income	$ 22.3	$ 10.2	$ 16.8