Revenue Recognition (Allowance for Doubtful Accounts) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Allowance for Doubtful Other Receivables, Current	$ 109.1	$ 43.2	$ 117.7	$ 7.4
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	25.9	38.4
Accounts Receivable, Allowance for Credit Loss, Writeoff	(39.5)	(8.6)
Accounts Receivable, Allowance for Credit Loss, Recovery	5.0	6.0
Entergy Arkansas [Member]
Disaggregation of Revenue [Line Items]
Allowance for Doubtful Other Receivables, Current	22.4	7.3	18.3	1.2
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	5.5	6.3
Accounts Receivable, Allowance for Credit Loss, Writeoff	(2.8)	(1.8)
Accounts Receivable, Allowance for Credit Loss, Recovery	1.4	1.6
Entergy Louisiana [Member]
Disaggregation of Revenue [Line Items]
Allowance for Doubtful Other Receivables, Current	39.8	14.5	45.7	1.9
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	11.7	14.1
Accounts Receivable, Allowance for Credit Loss, Writeoff	(19.5)	(3.5)
Accounts Receivable, Allowance for Credit Loss, Recovery	1.9	2.0
Entergy Mississippi [Member]
Disaggregation of Revenue [Line Items]
Allowance for Doubtful Other Receivables, Current	13.6	7.2	19.5	0.6
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	1.7	7.0
Accounts Receivable, Allowance for Credit Loss, Writeoff	(8.8)	(1.2)
Accounts Receivable, Allowance for Credit Loss, Recovery	1.2	0.8
Entergy New Orleans [Member]
Disaggregation of Revenue [Line Items]
Allowance for Doubtful Other Receivables, Current	21.1	8.4	17.4	3.2
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	4.6	5.5
Accounts Receivable, Allowance for Credit Loss, Writeoff	(1.1)	(1.0)
Accounts Receivable, Allowance for Credit Loss, Recovery	0.2	0.7
Entergy Texas [Member]
Disaggregation of Revenue [Line Items]
Allowance for Doubtful Other Receivables, Current	12.2	5.8	$ 16.8	$ 0.5
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	2.4	5.5
Accounts Receivable, Allowance for Credit Loss, Writeoff	(7.3)	(1.1)
Accounts Receivable, Allowance for Credit Loss, Recovery	$ 0.3	$ 0.9