DERIVATIVES AND HEDGING - Schedule of Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Total Assets
Gross Amounts Recognized	$ 1,408	$ 1,357
Current Risk Management Assets	246	352
Long-term Risk Management Assets	233	265
Total Risk Management Assets	479	617
Total Liabilities
Gross Amounts Recognized	1,180	970
Current Risk Management Liabilities	130	132
Long-term Risk Management Liabilities	165	178
Total Risk Management Liabilities	295	310
Total MTM Derivative Contract Net Assets (Liabilities)	184	307
Current Risk Management Assets
Total Assets
Gross Amounts Recognized	862	776
Gross Amounts Offset	(616)	(424)
Long-term Risk Management Assets
Total Assets
Gross Amounts Recognized	546	581
Gross Amounts Offset	(313)	(316)
Current Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	729	532
Gross Amounts Offset	(599)	(400)
Long-term Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	451	438
Gross Amounts Offset	(286)	(260)
AEP Texas
Total Assets
Gross Amounts Recognized	1	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 | Current Risk Management Assets
Total Assets
Gross Amounts Recognized	1	0
Gross Amounts Offset	(1)	0
AEP Texas | Long-term Risk Management Assets
Total Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
AEP Texas | Current Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
AEP Texas | Long-term Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
APCo
Total Assets
Gross Amounts Recognized	26	84
Current Risk Management Assets	22	81
Long-term Risk Management Assets	0	1
Total Risk Management Assets	22	82
Total Liabilities
Gross Amounts Recognized	10	6
Current Risk Management Liabilities	7	3
Long-term Risk Management Liabilities	0	0
Total Risk Management Liabilities	7	3
Total MTM Derivative Contract Net Assets (Liabilities)	15	79
APCo | Current Risk Management Assets
Total Assets
Gross Amounts Recognized	24	82
Gross Amounts Offset	(2)	(1)
APCo | Long-term Risk Management Assets
Total Assets
Gross Amounts Recognized	2	2
Gross Amounts Offset	(2)	(1)
APCo | Current Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	9	5
Gross Amounts Offset	(2)	(2)
APCo | Long-term Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	1	1
Gross Amounts Offset	(1)	(1)
I&M
Total Assets
Gross Amounts Recognized	18	24
Current Risk Management Assets	3	10
Long-term Risk Management Assets	0	0
Total Risk Management Assets	3	10
Total Liabilities
Gross Amounts Recognized	20	14
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)	3	10
I&M | Current Risk Management Assets
Total Assets
Gross Amounts Recognized	18	23
Gross Amounts Offset	(15)	(13)
I&M | Long-term Risk Management Assets
Total Assets
Gross Amounts Recognized	0	1
Gross Amounts Offset	0	(1)
I&M | Current Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	20	13
Gross Amounts Offset	(20)	(13)
I&M | Long-term Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	0	1
Gross Amounts Offset	0	(1)
OPCo
Total Assets
Gross Amounts Recognized	1	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	32	33
Current Risk Management Liabilities	4	5
Long-term Risk Management Liabilities	28	28
Total Risk Management Liabilities	32	33
Total MTM Derivative Contract Net Assets (Liabilities)	(32)	(33)
OPCo | Current Risk Management Assets
Total Assets
Gross Amounts Recognized	1	0
Gross Amounts Offset	(1)	0
OPCo | Long-term Risk Management Assets
Total Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
OPCo | Current Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	4	5
Gross Amounts Offset	0	0
OPCo | Long-term Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	28	28
Gross Amounts Offset	0	0
PSO
Total Assets
Gross Amounts Recognized	22	44
Current Risk Management Assets	21	42
Long-term Risk Management Assets	0	0
Total Risk Management Assets	21	42
Total Liabilities
Gross Amounts Recognized	35	30
Current Risk Management Liabilities	30	27
Long-term Risk Management Liabilities	5	1
Total Risk Management Liabilities	35	28
Total MTM Derivative Contract Net Assets (Liabilities)	(14)	14
PSO | Current Risk Management Assets
Total Assets
Gross Amounts Recognized	22	44
Gross Amounts Offset	(1)	(2)
PSO | Long-term Risk Management Assets
Total Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
PSO | Current Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	30	29
Gross Amounts Offset	0	(2)
PSO | Long-term Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	5	1
Gross Amounts Offset	0	0
SWEPCo
Total Assets
Gross Amounts Recognized	17	37
Current Risk Management Assets	15	35
Long-term Risk Management Assets	0	0
Total Risk Management Assets	15	35
Total Liabilities
Gross Amounts Recognized	14	13
Current Risk Management Liabilities	10	9
Long-term Risk Management Liabilities	3	2
Total Risk Management Liabilities	13	11
Total MTM Derivative Contract Net Assets (Liabilities)	2	24
SWEPCo | Current Risk Management Assets
Total Assets
Gross Amounts Recognized	17	37
Gross Amounts Offset	(2)	(2)
SWEPCo | Long-term Risk Management Assets
Total Assets
Gross Amounts Recognized	0	0
Gross Amounts Offset	0	0
SWEPCo | Current Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	11	11
Gross Amounts Offset	(1)	(2)
SWEPCo | Long-term Risk Management Liabilities
Total Liabilities
Gross Amounts Recognized	3	2
Gross Amounts Offset	$ 0	$ 0