RATE MATTERS - SWEPCo Rate Matters (Details) $ in Millions	1 Months Ended									3 Months Ended		12 Months Ended
	Jan. 31, 2025 USD ($)	Oct. 31, 2024 USD ($)	Jun. 30, 2024 USD ($)	Apr. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Jan. 31, 2022 USD ($)	Oct. 31, 2020 USD ($)	Jan. 31, 2018 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2024 USD ($) MW	Mar. 31, 2024 USD ($)
Securitization Bonds
Public Utilities, General Disclosures [Line Items]
Securitization Bonds											$ 368.9					$ 578.0
SOUTHWESTERN ELECTRIC POWER COMPANY
Public Utilities, General Disclosures [Line Items]
Storm related expense					$ 44.0
Disallowance of fuel costs			$ 535.0
SOUTHWESTERN ELECTRIC POWER COMPANY | Turk Generating Plant
Public Utilities, General Disclosures [Line Items]
Public utilities, base load | MW																600
Public utilities, net maximum capacity | MW																650
Public utilities, percentage of ownership																73.00%
Public utilities, net book value																$ 1,300.0
Public utilities, percentage not subject to cost-based rate recovery																20.00%
Public utilities, percentage subject to cost-based rate recovery																80.00%
Public utilities, favorable impact																	$ 32.0
SOUTHWESTERN ELECTRIC POWER COMPANY | Securitization Bonds
Public Utilities, General Disclosures [Line Items]
Securitization Bonds											0.0					$ 331.4
SOUTHWESTERN ELECTRIC POWER COMPANY | Securitization Bonds | Hurricane
Public Utilities, General Disclosures [Line Items]
Securitization Bonds																337.0
Debt issuance costs, gross																7.0
SOUTHWESTERN ELECTRIC POWER COMPANY | Securitization Bonds | Hurricane Laura And Delta
Public Utilities, General Disclosures [Line Items]
Securitization Bonds																180.0
SOUTHWESTERN ELECTRIC POWER COMPANY | Securitization Bonds | Catastrophe Storm Reserve
Public Utilities, General Disclosures [Line Items]
Securitization Bonds					$ 150.0											$ 150.0
SOUTHWESTERN ELECTRIC POWER COMPANY | Minimum | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Disallowance of fuel costs	$ 2.0
SOUTHWESTERN ELECTRIC POWER COMPANY | Minimum | Turk Generating Plant
Public Utilities, General Disclosures [Line Items]
Public utilities, production amount | MW																440
SOUTHWESTERN ELECTRIC POWER COMPANY | Maximum | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Disallowance of fuel costs	$ 25.0
SOUTHWESTERN ELECTRIC POWER COMPANY | Maximum | Turk Generating Plant
Public Utilities, General Disclosures [Line Items]
Public utilities, production amount | MW																477
2012 Texas Base Rate Case | SOUTHWESTERN ELECTRIC POWER COMPANY
Public Utilities, General Disclosures [Line Items]
2013 reversal of previously recorded regulatory disallowances															$ 114.0
Turk afudc disallowance											$ 86.0
Revenue refund provision										$ 160.0
Estimated turk afudc refunds, period		2 years
Estimated turk afudc refunds		$ 148.0
2012 Texas Base Rate Case | SOUTHWESTERN ELECTRIC POWER COMPANY | Minimum
Public Utilities, General Disclosures [Line Items]
Recommended customer refunds				$ 149.0
Recommended refund period				18 months
2012 Texas Base Rate Case | SOUTHWESTERN ELECTRIC POWER COMPANY | Maximum
Public Utilities, General Disclosures [Line Items]
Recommended customer refunds				$ 197.0
Recommended refund period				48 months
2016 Texas Base Rate Case | SOUTHWESTERN ELECTRIC POWER COMPANY
Public Utilities, General Disclosures [Line Items]
Requested net increase in texas annual revenues														$ 69.0
Requested return on equity														10.00%
Approved net increase in texas annual revenues									$ 50.0
Approved return on equity									9.60%
Approved additional vegetation management expenses									$ 2.0
Impairment charge total													$ 19.0
Impairment charge welsh plant, unit 2													7.0
Impairment charge disallowed plant investments													12.0
Additional revenues recognized to be surcharged to customers													32.0
Additional recognized expenses consisting primarily of depreciation and vegetation management													$ 7.0
2020 Texas Base Rate Case | SOUTHWESTERN ELECTRIC POWER COMPANY
Public Utilities, General Disclosures [Line Items]
Approved return on equity							9.25%
Impairment charge total												$ 12.0
Requested annual increase								$ 105.0
Requested return on equity								10.35%
Requested net annual increase								$ 90.0
Revised requested annual increase								100.0
Revised requested net annual increase								$ 85.0
Approved annual revenue increase							$ 39.0
Amount of approved increase related to vegetation management							5.0
Amount of approved increase related to storm catastrophe reserve							$ 2.0
2021 Louisiana Storm Cost Filing | SOUTHWESTERN ELECTRIC POWER COMPANY
Public Utilities, General Disclosures [Line Items]
Approved deferred storm costs						$ 150.0
Interim WACC						3.125%