FINANCING ACTIVITIES - Schedule of Interest Expense Incurred For Funds Borrowed from Utility Money Pool (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Short-Term Debt [Line Items]
Interest Expense	$ 2,026	$ 1,863	$ 1,807
AEP Texas
Short-Term Debt [Line Items]
Interest Expense	268	258	233
AEPTCo
Short-Term Debt [Line Items]
Interest Expense	234	214	195
APCo
Short-Term Debt [Line Items]
Interest Expense	283	271	270
I&M
Short-Term Debt [Line Items]
Interest Expense	151	134	137
OPCo
Short-Term Debt [Line Items]
Interest Expense	158	148	131
PSO
Short-Term Debt [Line Items]
Interest Expense	140	96	103
SWEPCo
Short-Term Debt [Line Items]
Interest Expense	157	106	147
Utility | Related Party | APCo
Short-Term Debt [Line Items]
Interest Expense	7	6	17
Utility | Related Party | I&M
Short-Term Debt [Line Items]
Interest Expense	2	4	3
Utility | Related Party | OPCo
Short-Term Debt [Line Items]
Interest Expense	4	4	10
Utility | Related Party | PSO
Short-Term Debt [Line Items]
Interest Expense	6	9	2
Utility | Nonutility | Related Party | AEP Texas
Short-Term Debt [Line Items]
Interest Expense	5	7	11
Utility | Nonutility | Related Party | SWEPCo
Short-Term Debt [Line Items]
Interest Expense	6	14	8
Utility | Direct Borrowing | Related Party | AEPTCo
Short-Term Debt [Line Items]
Interest Expense	$ 8	$ 4	$ 8