DERIVATIVES AND HEDGING - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cash collateral received from third-parties	$ 71	$ 87
Fair value of derivative liabilities subject to cross acceleration provisions	49	72
Fair value of derivative liabilities subject to cross default provisions	161	164
APCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair value of derivative liabilities subject to cross default provisions	2	1
PSO
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair value of derivative liabilities subject to cross default provisions	15	4
SWEPCo
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair value of derivative liabilities subject to cross default provisions	$ 4	$ 2
Commodity
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Maximum length of time to hedge exposure to variability	10 years
Cross acceleration provisions maximum third party obligation amount	$ 50
Cross default provisions maximum third party obligation amount	$ 50