Decommissioning Trust Funds (Schedule of Available-for-Sale Securities Reconciliation) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale [Line Items]
Debt Securities, Available-for-Sale	$ 2,155.0	$ 2,047.0
Debt Securities, Available-for-Sale, Unrealized Gain	28.0	7.0
Debt Securities, Available-for-Sale, Unrealized Loss	46.0	80.0
Entergy Arkansas [Member]
Debt Securities, Available-for-Sale [Line Items]
Debt Securities, Available-for-Sale	609.3	579.0
Debt Securities, Available-for-Sale, Unrealized Gain	7.6	1.2
Debt Securities, Available-for-Sale, Unrealized Loss	14.1	25.8
Entergy Louisiana [Member]
Debt Securities, Available-for-Sale [Line Items]
Debt Securities, Available-for-Sale	951.4	908.1
Debt Securities, Available-for-Sale, Unrealized Gain	12.6	3.6
Debt Securities, Available-for-Sale, Unrealized Loss	16.0	26.9
System Energy [Member]
Debt Securities, Available-for-Sale [Line Items]
Debt Securities, Available-for-Sale	594.6	559.8
Debt Securities, Available-for-Sale, Unrealized Gain	8.1	1.9
Debt Securities, Available-for-Sale, Unrealized Loss	$ 16.2	$ 27.6