FINANCING ACTIVITIES - Schedule of Fees Paid to AEP Credit for Customer Accounts Receivable Sold (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	$ 5,921	$ 5,631
APPALACHIAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	1,166	1,166
INDIANA MICHIGAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	937	755
OHIO POWER COMPANY
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	1,075	994
PUBLIC SERVICE COMPANY OF OKLAHOMA
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	439	394
SOUTHWESTERN ELECTRIC POWER COMPANY
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	571	531
Servicing Contracts | APPALACHIAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	4	4
Servicing Contracts | INDIANA MICHIGAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	4	4
Servicing Contracts | OHIO POWER COMPANY
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	8	7
Servicing Contracts | PUBLIC SERVICE COMPANY OF OKLAHOMA
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	3	3
Servicing Contracts | SOUTHWESTERN ELECTRIC POWER COMPANY
Disaggregation of Revenue [Line Items]
Total Revenues from Contracts with Customers	$ 4	$ 4