RATE MATTERS - Dolet Hills Power Station and Related Fuel Operations (Details) - Dolet Hills Power Station and Related Fuel Operations - SWEPCo - USD ($) $ in Millions	1 Months Ended
	Apr. 30, 2024	Feb. 29, 2024	Sep. 30, 2023	Aug. 31, 2022	Mar. 31, 2021	Mar. 31, 2025
Public Utilities, General Disclosures [Line Items]
Fuel supply provided, percentage						100.00%
Regulatory asset, net investment						$ 70
Regulatory asset, net under-recovered fuel costs						28
Louisiana
Public Utilities, General Disclosures [Line Items]
Regulatory asset, recovery of fuel costs					$ 20
Regulatory asset, recovery of fuel costs, deferred					35
Regulatory asset, fuel disallowance				$ 55
Regulatory asset, fuel disallowance, deferral				$ 35
Regulatory asset, refund to customer period				5 years
Regulatory asset, refund to customer, proposed amount		$ 55
Regulatory asset, deferral, denial of recovery		$ 35
Disallowance of fuel costs	$ 11
Regulatory asset						$ 24
Approved Recovery Period						3 years
Arkansas
Public Utilities, General Disclosures [Line Items]
Regulatory asset, recovery of fuel costs					$ 20
Regulatory asset, recovery of fuel costs, period					5 years
Texas
Public Utilities, General Disclosures [Line Items]
Regulatory asset, recovery of fuel costs			$ 48