Business Segment Information Business Segment Information (Restructuring Costs) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Restructuring Charges	$ 23.0	$ 89.0
Payments for Restructuring		100.0
Restructuring Reserve	73.0	73.0	$ 57.0	$ 91.0
Employee Retention and Severances Expenses and Other Benefits-Related Costs [Member]
Segment Reporting Information [Line Items]
Restructuring Charges	23.0	89.0
Payments for Restructuring		100.0
Restructuring Reserve	59.0	59.0	36.0	70.0
Economic Development Costs [Member]
Segment Reporting Information [Line Items]
Restructuring Charges	0.0	0.0
Payments for Restructuring		0.0
Restructuring Reserve	14.0	14.0	$ 21.0	$ 21.0
Entergy Wholesale Commodities [Member]
Segment Reporting Information [Line Items]
Restructuring Reserve, Settled without Cash	(7.0)	(7.0)
Entergy Wholesale Commodities [Member] | Employee Retention and Severances Expenses and Other Benefits-Related Costs [Member]
Segment Reporting Information [Line Items]
Restructuring Reserve, Settled without Cash	0.0	0.0
Entergy Wholesale Commodities [Member] | Economic Development Costs [Member]
Segment Reporting Information [Line Items]
Restructuring Reserve, Settled without Cash	$ (7.0)	$ (7.0)