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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
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	$ 0.0	$ (5.0)	$ 0.0	$ 4.0
Amount of gain (loss) recorded in income	1.0	0.0	1.0	0.0
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	6.0	(9.0)	6.0	(16.0)
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	41.0	44.0	73.0	75.0
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	2.1	10.5	10.1	15.1
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	4.9	(7.6)	4.9	(13.7)
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	25.8	14.3	43.4	29.5
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	0.9	(1.4)	0.7	(2.5)
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	9.8	8.5	17.6	11.6
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)	(0.1)
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	5.2	3.4	8.4	5.7
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 [Line Items]
Amount of gain (loss) recorded in income	$ (1.8)	$ 6.9	$ (5.3)	$ 12.1