RATE MATTERS - SWEPCo Rate Matters (Details) - SOUTHWESTERN ELECTRIC POWER COMPANY - USD ($) $ in Millions	1 Months Ended					12 Months Ended
	Nov. 30, 2025	Oct. 31, 2025	Mar. 31, 2025	Jan. 31, 2022	Oct. 31, 2020	Dec. 31, 2021
Pirkey Station
Public Utilities, General Disclosures [Line Items]
Public utilities, remaining net book recovery period	10 years
2020 Texas Base Rate Case
Public Utilities, General Disclosures [Line Items]
Requested annual base rate increase (decrease)					$ 105
Requested return on equity					10.35%
Requested net annual increase					$ 90
Revised requested annual increase					100
Revised requested net annual increase					$ 85
Approved annual revenue increase				$ 39
Approved return on equity				9.25%
Amount of approved increase related to vegetation management				$ 5
Amount of approved increase related to storm catastrophe reserve				$ 2
Impairment charge total						$ 12
2025 Arkansas Base Rate Case
Public Utilities, General Disclosures [Line Items]
Requested annual base rate increase (decrease)	$ 85		$ 114
Requested return on equity	9.65%		10.90%
Requested debt capital structure	55.70%		52.30%
Requested equity capital structure	44.30%		47.70%
Public utilities, return on recovery, percent	3.00%
2025 Texas Base Rate Case
Public Utilities, General Disclosures [Line Items]
Requested annual base rate increase (decrease)		$ 164
Requested return on equity		10.75%
Requested net annual increase		$ 95
Requested debt capital structure		48.00%
Requested equity capital structure		52.00%
2025 Texas Base Rate Case | Pirkey Station
Public Utilities, General Disclosures [Line Items]
Regulatory asset, requested to recovery amount		$ 21