SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT COMPANY - AEPTCO PARENT - RELATED PARTY TRANSACTIONS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Related Party Transaction [Line Items]
Long-term debt	$ 47,322	$ 42,643
Accrued interest	544	453
AEP TRANSMISSION COMPANY, LLC
Related Party Transaction [Line Items]
Long-term debt	6,599	5,768
Accrued interest	46	45
Accounts receivable – affiliated companies	153	134
Parent Company
Related Party Transaction [Line Items]
Long-term debt	10,100	8,406
Accrued interest	129	104
Interest income	102	108	$ 181
Parent Company | Subsidiaries
Related Party Transaction [Line Items]
Interest expense	31	28	33
Parent Company | Affiliated Entity
Related Party Transaction [Line Items]
Accounts receivable – affiliated companies	23	33
Parent Company | Short-Term Lending | Subsidiaries
Related Party Transaction [Line Items]
Interest income	88	84	164
Parent Company | AEP TRANSMISSION COMPANY, LLC
Related Party Transaction [Line Items]
Accrued interest	46	45
Accounts receivable – affiliated companies	65	62
Interest income	308	241	218
Parent Company | AEP TRANSMISSION COMPANY, LLC | Subsidiaries
Related Party Transaction [Line Items]
Long-term debt	6,600	5,800
Notes receivable – affiliated	6,600	8,600
Accrued interest	46	45
Accounts receivable – affiliated companies	65	62
Interest expense	252	238	215
Parent Company | AEP TRANSMISSION COMPANY, LLC | Long-Term Lending | Subsidiaries
Related Party Transaction [Line Items]
Interest income	306	238	215
Parent Company | AEP TRANSMISSION COMPANY, LLC | Short-Term Lending | Affiliated Entity
Related Party Transaction [Line Items]
Interest income	$ 2	$ 3	$ 3