Risk Management and Fair Values (Narrative) (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($) GWh MMBTU TWh counterparty	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) counterparty
Risk Management and Fair Values [Abstract]
Cash collateral posted	$ 1.0		$ 2.0
Derivative, Collateral, Obligation to Return Cash	3.0		$ 2.0
Cash flow hedges relating to power sales as part of net unrealized gains	8.0
Reclassified from accumulated other comprehensive income (OCI) to operating revenues	$ 5.0
Number of Derivative Contract Counterparties in a Liability Position | counterparty	3		3
Maturity of cash flow hedges, Tax	$ 18.0	$ 54.0
Maximum length of time over which Company is currently hedging the variability in future cash flows for forecasted power transactions, years	2 years
Planned generation sold forward from non utility nuclear power plants for the remainder of the period	86.00%
Planned Generation Sold Forward under financial derivatives	59.00%
Total planned generation for remainder of the period | TWh	19,900,000.0
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	59,830,000
Total volume of fixed transmission rights outstanding | GWh	18,365
Change in cash flow hedges due to ineffectiveness	$ (1.0)	(1.0)
Dollar amount of hedge contract in a liability position	13.0		$ 8.0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset and Liability Unrealized Gains (Loss) Included in Earnings	0.4	$ 6.0
Entergy Arkansas [Member]
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 0.2		0.3
Total volume of fixed transmission rights outstanding | GWh	4,197
Entergy Louisiana [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	50,230,000
Total volume of fixed transmission rights outstanding | GWh	7,669
Entergy Mississippi [Member]
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 0.1		$ 0.1
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	9,600,000
Total volume of fixed transmission rights outstanding | GWh	3,142
Entergy New Orleans [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | GWh	883
Entergy Texas [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | GWh	2,434