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	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
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 [Line Items]
Amount of gain (loss) recognized in AOCI	$ (2.0)	$ (9.0)	$ 2.0	$ 6.0
Amount of gain (loss) recorded in income	0.0	0.0	0.0	(9.0)
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 [Line Items]
Amount of gain (loss) recognized in AOCI	0.0	0.0	0.0	0.0
Amount of gain (loss) recorded in income	(3.0)	25.0	(20.0)	(5.0)
Purchased Power Expense [Member] | Fixed Transmission Rights (FTRs) [Member]
Effect Of Derivative Instruments Not Designated As Hedging Instruments On The Consolidated Statements Of Income [Line Items]
Amount of gain (loss) recognized in AOCI	0.0	0.0	0.0	0.0
Amount of gain (loss) recorded in income	28.0	37.0	103.0	96.0
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 [Line Items]
Amount of gain (loss) recorded in income	4.2	7.1	19.3	20.3
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 [Line Items]
Amount of gain (loss) recorded in income	(2.6)	19.5	(16.3)	(4.6)
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 [Line Items]
Amount of gain (loss) recorded in income	9.4	20.4	38.9	52.5
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 [Line Items]
Amount of gain (loss) recorded in income	(0.6)	5.3	(3.1)	0.3
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 [Line Items]
Amount of gain (loss) recorded in income	4.7	6.7	16.3	11.1
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 [Line Items]
Amount of gain (loss) recorded in income			(0.1)	(0.5)
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 [Line Items]
Amount of gain (loss) recorded in income	1.9	0.9	7.7	2.8
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 [Line Items]
Amount of gain (loss) recorded in income	$ 7.0	$ 1.8	$ 19.2	$ 8.7