FINANCING ACTIVITIES - Schedule of Proceeds on Sale of Receivables to AEP Credit (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
APCo
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	$ 495.4	$ 504.6	$ 1,530.0	$ 1,487.9
I&M
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	682.6	576.7	1,812.7	1,608.5
OPCo
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	927.8	860.0	2,523.3	2,477.2
PSO
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	659.6	611.5	1,466.3	1,398.1
SWEPCo
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of receivables to AEP Credit	$ 549.9	$ 531.4	$ 1,434.0	$ 1,428.7