RATE MATTERS - February 2021 Severe Winter Weather Impacts in SPP (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Dec. 31, 2024	Mar. 31, 2021
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Assets	$ 4,950.2	$ 5,129.2
SWEPCo
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Assets	922.2	921.3
February 2021 Severe Storm Fuel Costs | SWEPCo
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Assets	121.9	180.5
February 2021 Severe Storm Fuel Costs | Arkansas | SWEPCo
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Assets	$ 25.1	37.2
Approved Recovery Period	6 years
February 2021 Severe Storm Fuel Costs | Louisiana | SWEPCo
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Assets	$ 47.2	70.6
Approved Recovery Period			5 years
February 2021 Severe Storm Fuel Costs | Texas | SWEPCo
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Assets	$ 49.6	$ 72.7
Approved Recovery Period	5 years
Approved Carrying Charge	1.65%