Risk Management and Fair Values (Fair Values Of Derivative Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets:
Derivative asset as hedging instrument offset	$ (4.0)
Liabilities:
Cash collateral posted	1.0	$ 2.0
Prepayments And Other [Member] | Electricity Futures Forwards Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Designated as Hedging Instrument [Member]
Assets:
Derivative asset, fair value	19.0	25.0
Derivative asset as hedging instrument offset	(19.0)	(14.0)
Derivative asset, net	0.0	11.0
Prepayments And Other [Member] | Electricity Futures Forwards Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, fair value	9.0	18.0
Derivative asset as hedging instrument offset	(9.0)	(13.0)
Derivative asset, net	0.0	5.0
Prepayments And Other [Member] | Natural Gas Swaps [Member] | Utility [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, fair value		13.0
Derivative asset as hedging instrument offset		0.0
Derivative asset, net		13.0
Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Utility and Entergy Wholesale Commodities [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, fair value	22.0	22.0
Derivative asset as hedging instrument offset	(1.0)	(1.0)
Derivative asset, net	21.0	21.0
Other Deferred Debits And Other Assets [Member] | Electricity Futures Forwards Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Designated as Hedging Instrument [Member]
Assets:
Derivative asset, fair value	19.0	6.0
Derivative asset as hedging instrument offset	(14.0)	(6.0)
Derivative asset, net	5.0	0.0
Other Deferred Debits And Other Assets [Member] | Electricity Futures Forwards Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, fair value		5.0
Derivative asset as hedging instrument offset		(5.0)
Derivative asset, net		0.0
Other Non-Current Liabilities [Member] | Electricity Futures Forwards Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Designated as Hedging Instrument [Member]
Liabilities:
Derivative Liability, Fair Value, Gross Liability	17.0	16.0
Derivative liability as hedging instrument offset	(14.0)	(7.0)
Derivative liability, net	3.0	9.0
Derivative Liability, Fair Value, Gross Liability	17.0	16.0
Other Non-Current Liabilities [Member] | Electricity Futures Forwards Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative Liability, Fair Value, Gross Liability		4.0
Derivative liability as hedging instrument offset		(4.0)
Derivative liability, net		0.0
Derivative Liability, Fair Value, Gross Liability		4.0
Other Current Liabilities [Member] | Electricity Futures Forwards Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Designated as Hedging Instrument [Member]
Liabilities:
Derivative Liability, Fair Value, Gross Liability	86.0	11.0
Derivative liability as hedging instrument offset	(20.0)	(10.0)
Derivative liability, net	66.0	1.0
Derivative Liability, Fair Value, Gross Liability	86.0	11.0
Other Current Liabilities [Member] | Electricity Futures Forwards Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative Liability, Fair Value, Gross Liability	9.0	18.0
Derivative liability as hedging instrument offset	(8.0)	(17.0)
Derivative liability, net	1.0	1.0
Derivative Liability, Fair Value, Gross Liability	9.0	18.0
Other Current Liabilities [Member] | Natural Gas Swaps [Member] | Utility [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative Liability, Fair Value, Gross Liability	6.0
Derivative liability as hedging instrument offset	0.0
Derivative liability, net	6.0
Derivative Liability, Fair Value, Gross Liability	6.0
Entergy Louisiana [Member] | Prepayments And Other [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, net		10.9
Entergy Louisiana [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, net	10.2	8.5
Entergy Louisiana [Member] | Other Current Liabilities [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative liability, net	5.0
Entergy Mississippi [Member] | Prepayments And Other [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, net		2.3
Entergy Mississippi [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, net	2.1	3.2
Entergy Mississippi [Member] | Other Current Liabilities [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative liability, net	1.2
Entergy New Orleans [Member] | Prepayments And Other [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, net		0.2
Entergy New Orleans [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, net	2.2	1.1
Entergy New Orleans [Member] | Other Current Liabilities [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative liability, net	0.2
Entergy Texas [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, net	3.4	3.1
Entergy Arkansas [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative asset, net	$ 3.0	$ 5.4