Risk Management and Fair Values (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016 USD ($) MMBTU MWh	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) MMBTU MWh counterparty	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) counterparty
Risk Management and Fair Values [Abstract]
Letters of Credit Held	$ 49.0		$ 49.0
Cash collateral posted	4.0		4.0		$ 9.0
Derivative, Collateral, Obligation to Return Cash	4.0		4.0		$ 68.0
Cash flow hedges relating to power sales as part of net unrealized gains			85.0
Reclassified from accumulated other comprehensive income (OCI) to operating revenues			$ 66.0
Number of Derivative Contract Counterparties in a Liability Position | counterparty			0		2
Maturity of cash flow hedges, Tax	$ 13.0	$ 30.0	$ 83.0	$ 61.0
Maximum length of time over which Company is currently hedging the variability in future cash flows for forecasted power transactions, years			2 years 3 months
Planned generation sold forward from non utility nuclear power plants for the remainder of the period			90.00%
Planned Generation Sold Forward under financial derivatives	61.00%		61.00%
Total planned generation for remainder of the period | MWh			9,000,000
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	25,604,000		25,604,000
Total volume of fixed transmission rights outstanding | MWh	74,491,000		74,491,000
Change in cash flow hedges due to ineffectiveness	$ 6.4	(0.9)	$ 6.1	0.0
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	$ 1.0	$ 12.0	$ 1.0	$ 5.0
Entergy Arkansas [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | MWh	16,859,000		16,859,000
Entergy Louisiana [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	18,780,000		18,780,000
Total volume of fixed transmission rights outstanding | MWh	31,476,000		31,476,000
Entergy Mississippi [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	5,750,000		5,750,000
Total volume of fixed transmission rights outstanding | MWh	12,374,000		12,374,000
Entergy New Orleans [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	1,074,000		1,074,000
Total volume of fixed transmission rights outstanding | MWh	3,640,000		3,640,000
Entergy Texas [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | MWh	9,745,000		9,745,000