DERIVATIVES AND HEDGING - Schedule of Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Total Assets
Gross Amounts Recognized	$ 1,357	$ 1,039
Current Risk Management Assets	352	210
Long-term Risk Management Assets	265	289
Total Risk Management Assets	617	499
Total Liabilities
Gross Amounts Recognized	970	780
Current Risk Management Liabilities	132	100
Long-term Risk Management Liabilities	178	224
Total Risk Management Liabilities	310	324
Total MTM Derivative Contract Net Assets (Liabilities)	307	175
Prepaid Expenses and Other Current Assets
Total Assets
Gross Amounts Recognized	776	479
Gross Amounts Offset	(424)	(269)
Other Noncurrent Assets
Total Assets
Gross Amounts Recognized	581	560
Gross Amounts Offset	(316)	(271)
Other Current Liabilities
Total Liabilities
Gross Amounts Recognized	532	351
Gross Amounts Offset	(400)	(251)
Other Noncurrent Liabilities
Total Liabilities
Gross Amounts Recognized	438	429
Gross Amounts Offset	(260)	(205)
AEP Texas
Total Assets
Gross Amounts Recognized	0	0
Current Risk Management Assets	0	0
Long-term Risk Management Assets	0	0
Total Risk Management Assets	0	0
Total Liabilities
Gross Amounts Recognized	0	0
Current Risk Management Liabilities	0	0
Long-term Risk Management Liabilities	0	0
Total Risk Management Liabilities	0	0
Total MTM Derivative Contract Net Assets (Liabilities)	0	0
AEP Texas | Prepaid Expenses and Other Current Assets
Total Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
AEP Texas | Other Noncurrent Assets
Total Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
AEP Texas | Other Current Liabilities
Total Liabilities
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
AEP Texas | Other Noncurrent Liabilities
Total Liabilities
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
APCo
Total Assets
Gross Amounts Recognized	84	42
Current Risk Management Assets	81	36
Long-term Risk Management Assets	1	1
Total Risk Management Assets	82	37
Total Liabilities
Gross Amounts Recognized	6	7
Current Risk Management Liabilities	3	2
Long-term Risk Management Liabilities	0	0
Total Risk Management Liabilities	3	2
Total MTM Derivative Contract Net Assets (Liabilities)	79	35
APCo | Prepaid Expenses and Other Current Assets
Total Assets
Gross Amounts Recognized	82	40
Gross Amounts Offset	(1)	(4)
APCo | Other Noncurrent Assets
Total Assets
Gross Amounts Recognized	2	2
Gross Amounts Offset	(1)	(1)
APCo | Other Current Liabilities
Total Liabilities
Gross Amounts Recognized	5	7
Gross Amounts Offset	(2)	(5)
APCo | Other Noncurrent Liabilities
Total Liabilities
Gross Amounts Recognized	1	0
Gross Amounts Offset	(1)	0
I&M
Total Assets
Gross Amounts Recognized	24	30
Current Risk Management Assets	10	18
Long-term Risk Management Assets	0	0
Total Risk Management Assets	10	18
Total Liabilities
Gross Amounts Recognized	14	13
Current Risk Management Liabilities	0	0
Long-term Risk Management Liabilities	0	0
Total Risk Management Liabilities	0	0
Total MTM Derivative Contract Net Assets (Liabilities)	10	18
I&M | Prepaid Expenses and Other Current Assets
Total Assets
Gross Amounts Recognized	23	29
Gross Amounts Offset	(13)	(11)
I&M | Other Noncurrent Assets
Total Assets
Gross Amounts Recognized	1	1
Gross Amounts Offset	(1)	(1)
I&M | Other Current Liabilities
Total Liabilities
Gross Amounts Recognized	13	11
Gross Amounts Offset	(13)	(11)
I&M | Other Noncurrent Liabilities
Total Liabilities
Gross Amounts Recognized	1	2
Gross Amounts Offset	(1)	(2)
OPCo
Total Assets
Gross Amounts Recognized	0	0
Current Risk Management Assets	0	0
Long-term Risk Management Assets	0	0
Total Risk Management Assets	0	0
Total Liabilities
Gross Amounts Recognized	33	48
Current Risk Management Liabilities	5	7
Long-term Risk Management Liabilities	28	40
Total Risk Management Liabilities	33	47
Total MTM Derivative Contract Net Assets (Liabilities)	(33)	(47)
OPCo | Prepaid Expenses and Other Current Assets
Total Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
OPCo | Other Noncurrent Assets
Total Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
OPCo | Other Current Liabilities
Total Liabilities
Gross Amounts Recognized	5	8
Gross Amounts Offset	0	(1)
OPCo | Other Noncurrent Liabilities
Total Liabilities
Gross Amounts Recognized	28	40
Gross Amounts Offset	0	0
PSO
Total Assets
Gross Amounts Recognized	44	24
Current Risk Management Assets	42	21
Long-term Risk Management Assets	0	1
Total Risk Management Assets	42	22
Total Liabilities
Gross Amounts Recognized	30	8
Current Risk Management Liabilities	27	6
Long-term Risk Management Liabilities	1	0
Total Risk Management Liabilities	28	6
Total MTM Derivative Contract Net Assets (Liabilities)	14	16
PSO | Prepaid Expenses and Other Current Assets
Total Assets
Gross Amounts Recognized	44	22
Gross Amounts Offset	(2)	(1)
PSO | Other Noncurrent Assets
Total Assets
Gross Amounts Recognized	0	2
Gross Amounts Offset	0	(1)
PSO | Other Current Liabilities
Total Liabilities
Gross Amounts Recognized	29	8
Gross Amounts Offset	(2)	(2)
PSO | Other Noncurrent Liabilities
Total Liabilities
Gross Amounts Recognized	1	0
Gross Amounts Offset	0	0
SWEPCo
Total Assets
Gross Amounts Recognized	37	19
Current Risk Management Assets	35	18
Long-term Risk Management Assets	0	0
Total Risk Management Assets	35	18
Total Liabilities
Gross Amounts Recognized	13	3
Current Risk Management Liabilities	9	2
Long-term Risk Management Liabilities	2	0
Total Risk Management Liabilities	11	2
Total MTM Derivative Contract Net Assets (Liabilities)	24	16
SWEPCo | Prepaid Expenses and Other Current Assets
Total Assets
Gross Amounts Recognized	37	19
Gross Amounts Offset	(2)	(1)
SWEPCo | Other Noncurrent Assets
Total Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
SWEPCo | Other Current Liabilities
Total Liabilities
Gross Amounts Recognized	11	3
Gross Amounts Offset	(2)	(1)
SWEPCo | Other Noncurrent Liabilities
Total Liabilities
Gross Amounts Recognized	2	0
Gross Amounts Offset	$ 0	$ 0