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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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	$ (5.0)	$ (10.0)	$ 4.0	$ 15.0
Amount of gain (loss) recorded in income	0.0	(6.0)	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	(9.0)	(6.0)	(16.0)	(30.0)
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	44.0	38.0	75.0	59.0
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	10.5	5.5	15.1	13.3
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	(7.6)	(4.9)	(13.7)	(24.2)
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 [Line Items]
Amount of gain (loss) recorded in income	14.3	21.6	29.5	32.1
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	(1.4)	(0.9)	(2.5)	(5.0)
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	8.5	3.6	11.6	4.4
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	3.4	1.4	5.7	1.9
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	$ 6.9	$ 5.4	$ 12.1	$ 6.9