Decommissioning Trust Funds (Securities Held) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Total	$ 2,177.0	$ 2,617.0
Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Total	2,177.0	2,617.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	65.0	197.0
Debt Securities, Available-for-sale, Unrealized Loss Position	12.0	3.0
Entergy Louisiana [Member]
Debt Securities, Available-for-sale [Line Items]
Total	794.2	632.2
Entergy Louisiana [Member] | Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Total	794.2	632.2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	31.3	51.3
Debt Securities, Available-for-sale, Unrealized Loss Position	3.3	0.5
Entergy Arkansas [Member]
Debt Securities, Available-for-sale [Line Items]
Total	526.3	447.9
Entergy Arkansas [Member] | Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Total	526.3	447.9
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	11.4	27.7
Debt Securities, Available-for-sale, Unrealized Loss Position	4.7	0.3
System Energy [Member]
Debt Securities, Available-for-sale [Line Items]
Total	524.5	427.7
System Energy [Member] | Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Total	524.5	427.7
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	11.8	30.0
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 2.9	$ 0.8