Rate and Regulatory Matters (Unit Power Sales Agreement - Narrative) (Details) - System Energy [Member] - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Oct. 31, 2021	Sep. 30, 2023	Dec. 31, 2024
Depreciation Amendment Proceeding [Member]
Reduction to depreciation expense resulting from differences in depreciation rates		$ 41.0
Pension Costs Amendment Proceeding [Member]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 8.9
Pension Costs Amendment Proceeding [Member] | Minimum [Member]
FERC ALJ recommended refunds			$ 16.0
Pension Costs Amendment Proceeding [Member] | Maximum [Member]
FERC ALJ recommended refunds			$ 21.0