Risk Management and Fair Values (Narrative) (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) GWh MMBTU	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) GWh MMBTU TWh	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) counterparty
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 19.0		$ 19.0
Cash collateral posted	1.0		1.0		$ 2.0
Derivative, Collateral, Obligation to Return Cash	3.0		3.0
Letters of Credit Held	19.0		19.0
Cash flow hedges relating to power sales as part of net unrealized gains			39.0
Reclassified from accumulated other comprehensive income (OCI) to operating revenues			30.0
Number of Derivative Contract Counterparties in a Liability Position | counterparty					3
Maturity of cash flow hedges, Tax	$ 4.0	$ 16.0	$ 22.0	$ 70.0
Maximum length of time over which Company is currently hedging the variability in future cash flows for forecasted power transactions, years			2 years 6 months
Planned generation sold forward from non utility nuclear power plants for the remainder of the period			89.00%
Planned Generation Sold Forward under financial derivatives	59.00%		59.00%
Total planned generation for remainder of the period | TWh			15,000,000
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	34,696,750		34,696,750
Total volume of fixed transmission rights outstanding | GWh	106,060		106,060
Change in cash flow hedges due to ineffectiveness	$ 5.0	(3.0)	$ 4.0	0.0
Dollar amount of hedge contract in a liability position					$ 8.0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset and Liability Unrealized Gains (Loss) Included in Earnings	(0.1)	(6.0)	0.3
Entergy Arkansas [Member]
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 0.3		$ 0.3		0.3
Total volume of fixed transmission rights outstanding | GWh	24,188		24,188
Entergy Louisiana [Member]
Risk Management and Fair Values [Abstract]
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	29,110,800		29,110,800
Total volume of fixed transmission rights outstanding | GWh	47,173		47,173
Entergy Mississippi [Member]
Risk Management and Fair Values [Abstract]
Letters of Credit Outstanding, Amount	$ 0.1		$ 0.1		$ 0.1
Total volume of natural gas swaps outstanding (MMBtu) | MMBTU	5,585,950		5,585,950
Total volume of fixed transmission rights outstanding | GWh	14,075		14,075
Entergy New Orleans [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | GWh	5,316		5,316
Entergy Texas [Member]
Risk Management and Fair Values [Abstract]
Total volume of fixed transmission rights outstanding | GWh	14,572		14,572
Electricity Swaps And Options [Member]
Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset and Liability, Realized Gain (Loss) Included In Earnings	$ 4.0	(9.0)	$ 4.0	(9.0)
Fixed Transmission Rights (FTRs) [Member]
Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset and Liability, Realized Gain (Loss) Included In Earnings	$ 0.0	$ 0.0	$ 0.0	$ 0.0