Risk Management and Fair Values (Narrative) (Details) TWh in Millions, $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($) GWh MMBTU counterparty	Mar. 31, 2018 USD ($)	Dec. 31, 2019 TWh	Dec. 31, 2018 USD ($) counterparty
Risk Management and Fair Values [Abstract]
Cash flow hedges relating to power sales as part of net unrealized gains	$ (53.0)
Reclassified from accumulated other comprehensive income (OCI) to operating revenues	(39.0)
Maturity of cash flow hedges, Tax	$ 11.0	$ (6.0)
Maximum length of time over which Company is currently hedging the variability in future cash flows for forecasted power transactions, years	2 years
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	45,740,000
Total volume of fixed transmission rights outstanding | GWh	18,928
Change in cash flow hedges due to ineffectiveness		13.3
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset and Liability Unrealized Gains (Loss) Included in Earnings	$ (4.9)	$ 0.2
Entergy Arkansas [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | GWh	4,099
Entergy Louisiana [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	36,540,000
Total volume of fixed transmission rights outstanding | GWh	8,235
Entergy Mississippi [Member]
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 0.4			$ 0.2
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	9,200,000
Total volume of fixed transmission rights outstanding | GWh	2,520
Entergy New Orleans [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | GWh	948
Entergy Texas [Member]
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 1.5			4.1
Total volume of fixed transmission rights outstanding | GWh	3,047
Gas Hedge Contracts [Member] | Entergy Louisiana [Member]
Risk Management and Fair Values [Abstract]
Maximum Length of Time Hedged in Cash Flow Hedge	5 years
Gas Hedge Contracts [Member] | Entergy Mississippi [Member]
Risk Management and Fair Values [Abstract]
Maximum Length of Time Hedged in Cash Flow Hedge	7 months
Entergy Wholesale Commodities [Member]
Risk Management and Fair Values [Abstract]
Cash collateral posted	$ 19.0			$ 19.0
Derivative, Collateral, Obligation to Return Cash	1.0
Letters of Credit Held	$ 4.0
Number of Derivative Contract Counterparties in a Liability Position | counterparty	7			6
Dollar amount of hedge contract in a liability position	$ 49.0			$ 34.0
Utility [Member]
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 2.0			$ 4.0
Subsequent Event [Member]
Risk Management and Fair Values [Abstract]
Planned generation sold forward from non utility nuclear power plants for the remainder of the period			98.00%
Planned Generation From Non Nuclear Power Plants Sold Forward Under Financial Hedges			72.00%
Total planned generation for remainder of the period | TWh			18.6