Risk Management and Fair Values (Narrative) (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($) MMBTU MWh counterparty	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($) counterparty
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 0.4
Cash collateral posted			$ 9.0
Derivative, Collateral, Obligation to Return Cash	66.0		$ 68.0
Cash flow hedges relating to power sales as part of net unrealized gains	152.0
Reclassified from accumulated other comprehensive income (OCI) to operating revenues	$ 134.0
Number of Derivative Contract Counterparties in a Liability Position | counterparty	0		2
Maturity of cash flow hedges, Tax	$ 54.0	$ 5.0
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	88.00%
Planned Generation Sold Forward under financial derivatives	60.00%
Total planned generation for remainder of the period | MWh	25,000,000
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	57,500,000
Total volume of fixed transmission rights outstanding | MWh	18,305,000
Change in cash flow hedges due to ineffectiveness	$ (1.0)	(1.0)
Dollar amount of hedge contract in a liability position			$ 2.0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset and Liability Unrealized Gains (Loss) Included in Earnings	$ 6.0	$ (87.0)
Entergy Arkansas [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | MWh	3,894,000
Entergy Louisiana [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	46,330,000
Total volume of fixed transmission rights outstanding | MWh	8,385,000
Entergy Mississippi [Member]
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 0.4
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	11,170,000
Total volume of fixed transmission rights outstanding | MWh	2,436,000
Entergy New Orleans [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | MWh	1,398,000
Entergy Texas [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | MWh	2,086,000