Stock-Based Compensation (Financial Information For Stock Options) (Details) - Employee Stock Option [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee service share-based compensation, aggregate disclosures
Compensation expense included in Entergy's net income	$ 1.1	$ 1.1	$ 3.3	$ 3.3
Tax benefit recognized in Entergy's net income	0.5	0.5	1.3	1.3
Compensation cost capitalized as part of fixed assets and inventory	$ 0.2	$ 0.2	$ 0.6	$ 0.6