Risk Management and Fair Values (Fair Values Of Derivative Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Assets:
Derivative asset as hedging instrument offset	$ (4.0)
Other Non-Current Liabilities [Member] | Electricity Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Designated As Hedging Instrument [Member]
Liabilities:
Derivative liability as hedging instrument offset	(7.0)	$ (7.0)
Derivative Liability, Fair Value, Gross Liability	7.0	16.0
Derivative Liability	0.0	9.0
Other Non-Current Liabilities [Member] | Electricity Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative liability as hedging instrument offset	(1.0)	(4.0)
Derivative Liability, Fair Value, Gross Liability	1.0	4.0
Derivative Liability	0.0	0.0
Other Deferred Debits And Other Assets [Member] | Electricity Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Designated As Hedging Instrument [Member]
Assets:
Derivative Asset, Fair Value, Gross Asset	29.0	6.0
Derivative asset as hedging instrument offset	(7.0)	(6.0)
Derivative Asset	22.0	0.0
Other Deferred Debits And Other Assets [Member] | Electricity Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset, Fair Value, Gross Asset	1.0	5.0
Derivative asset as hedging instrument offset	(1.0)	(5.0)
Derivative Asset	0.0	0.0
Prepayments And Other [Member] | Electricity Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Designated As Hedging Instrument [Member]
Assets:
Derivative Asset, Fair Value, Gross Asset	52.0	25.0
Derivative asset as hedging instrument offset	(22.0)	(14.0)
Derivative Asset	30.0	11.0
Prepayments And Other [Member] | Electricity Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset, Fair Value, Gross Asset	11.0	18.0
Derivative asset as hedging instrument offset	(3.0)	(13.0)
Derivative Asset	8.0	5.0
Prepayments And Other [Member] | Natural Gas Swaps [Member] | Utility [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset, Fair Value, Gross Asset		13.0
Derivative asset as hedging instrument offset		0.0
Derivative Asset		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, Gross Asset	39.0	22.0
Derivative asset as hedging instrument offset	(2.0)	(1.0)
Derivative Asset	37.0	21.0
Other Current Liabilities [Member] | Electricity Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Designated As Hedging Instrument [Member]
Liabilities:
Derivative liability as hedging instrument offset	(17.0)	(10.0)
Derivative Liability, Fair Value, Gross Liability	17.0	11.0
Derivative Liability	0.0	1.0
Other Current Liabilities [Member] | Electricity Swaps And Options [Member] | Entergy Wholesale Commodities [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative liability as hedging instrument offset	(8.0)	(17.0)
Derivative Liability, Fair Value, Gross Liability	8.0	18.0
Derivative Liability	0.0	1.0
Other Current Liabilities [Member] | Natural Gas Swaps [Member] | Utility [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative liability as hedging instrument offset	0.0
Derivative Liability, Fair Value, Gross Liability	1.0
Derivative Liability	1.0
Entergy Louisiana [Member] | Prepayments And Other [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset		10.9
Entergy Louisiana [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset	18.8	8.5
Entergy Louisiana [Member] | Other Current Liabilities [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative Liability	0.7
Entergy Mississippi [Member] | Prepayments And Other [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset		2.3
Entergy Mississippi [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset	5.5	3.2
Entergy Mississippi [Member] | Other Current Liabilities [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Liabilities:
Derivative Liability	0.2
Entergy New Orleans [Member] | Prepayments And Other [Member] | Natural Gas Swaps [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset		0.2
Entergy New Orleans [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset	3.5	1.1
Entergy Arkansas [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset	4.4	5.4
Entergy Texas [Member] | Prepayments And Other [Member] | Fixed Transmission Rights (FTRs) [Member] | Not Designated As Hedging Instrument [Member]
Assets:
Derivative Asset	$ 5.0	$ 3.1