Decommissioning Trust Funds (Schedule of Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale [Line Items]
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 273.0	$ 1,102.0
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	553.0	510.0
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value	826.0	1,612.0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	4.0	24.0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	42.0	56.0
Debt Securities, Available-for-Sale, Unrealized Loss Position	46.0	80.0
Entergy Arkansas [Member]
Debt Securities, Available-for-Sale [Line Items]
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	49.6	282.8
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	224.7	195.0
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value	274.3	477.8
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0.6	8.2
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	13.5	17.6
Debt Securities, Available-for-Sale, Unrealized Loss Position	14.1	25.8
Entergy Louisiana [Member]
Debt Securities, Available-for-Sale [Line Items]
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	154.5	543.8
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	177.5	178.4
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value	332.0	722.2
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	3.2	8.8
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	12.8	18.1
Debt Securities, Available-for-Sale, Unrealized Loss Position	16.0	26.9
System Energy [Member]
Debt Securities, Available-for-Sale [Line Items]
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	68.7	275.6
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	150.9	136.8
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value	219.6	412.4
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0.6	6.8
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	15.6	20.8
Debt Securities, Available-for-Sale, Unrealized Loss Position	$ 16.2	$ 27.6