DERIVATIVES AND HEDGING - Schedule of Location and Fair Value of Derivative Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Derivative [Line Items]
Total Assets	$ 1,357	$ 1,039
Total Liabilities	970	780
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	387	259
Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	776	479
Other Noncurrent Assets
Derivative [Line Items]
Total Assets	581	560
Other Current Liabilities
Derivative [Line Items]
Total Liabilities	532	351
Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	438	429
AEP Texas
Derivative [Line Items]
Total Assets	0	0
Total Liabilities	0	0
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	0	0
AEP Texas | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
AEP Texas | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
AEP Texas | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
AEP Texas | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
APCo
Derivative [Line Items]
Total Assets	84	42
Total Liabilities	6	7
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	78	35
APCo | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	82	40
APCo | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	2	2
APCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	5	7
APCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	1	0
I&M
Derivative [Line Items]
Total Assets	24	30
Total Liabilities	14	13
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	10	17
I&M | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	23	29
I&M | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	1	1
I&M | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	13	11
I&M | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	1	2
OPCo
Derivative [Line Items]
Total Assets	0	0
Total Liabilities	33	48
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	(33)	(48)
OPCo | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
OPCo | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
OPCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	5	8
OPCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	28	40
PSO
Derivative [Line Items]
Total Assets	44	24
Total Liabilities	30	8
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	14	16
PSO | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	44	22
PSO | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	2
PSO | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	29	8
PSO | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	1	0
SWEPCo
Derivative [Line Items]
Total Assets	37	19
Total Liabilities	13	3
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	24	16
SWEPCo | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	37	19
SWEPCo | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
SWEPCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	11	3
SWEPCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	2	0
Commodity | Not Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	720	425
Commodity | Not Designated as Hedging Instrument | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	518	475
Commodity | Not Designated as Hedging Instrument | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	500	304
Commodity | Not Designated as Hedging Instrument | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	420	391
Commodity | Not Designated as Hedging Instrument | AEP Texas | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Not Designated as Hedging Instrument | AEP Texas | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Not Designated as Hedging Instrument | AEP Texas | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Not Designated as Hedging Instrument | AEP Texas | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Not Designated as Hedging Instrument | APCo | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	82	40
Commodity | Not Designated as Hedging Instrument | APCo | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	2	2
Commodity | Not Designated as Hedging Instrument | APCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	5	7
Commodity | Not Designated as Hedging Instrument | APCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	1	0
Commodity | Not Designated as Hedging Instrument | I&M | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	23	29
Commodity | Not Designated as Hedging Instrument | I&M | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	1	1
Commodity | Not Designated as Hedging Instrument | I&M | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	13	11
Commodity | Not Designated as Hedging Instrument | I&M | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	1	2
Commodity | Not Designated as Hedging Instrument | OPCo | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Not Designated as Hedging Instrument | OPCo | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Not Designated as Hedging Instrument | OPCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	5	8
Commodity | Not Designated as Hedging Instrument | OPCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	28	40
Commodity | Not Designated as Hedging Instrument | PSO | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	44	22
Commodity | Not Designated as Hedging Instrument | PSO | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	2
Commodity | Not Designated as Hedging Instrument | PSO | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	29	8
Commodity | Not Designated as Hedging Instrument | PSO | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	1	0
Commodity | Not Designated as Hedging Instrument | SWEPCo | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	37	19
Commodity | Not Designated as Hedging Instrument | SWEPCo | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Not Designated as Hedging Instrument | SWEPCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	11	3
Commodity | Not Designated as Hedging Instrument | SWEPCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	2	0
Commodity | Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	56	54
Commodity | Designated as Hedging Instrument | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	63	85
Commodity | Designated as Hedging Instrument | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	16	11
Commodity | Designated as Hedging Instrument | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	5	3
Commodity | Designated as Hedging Instrument | AEP Texas | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | AEP Texas | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | AEP Texas | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | AEP Texas | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | APCo | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | APCo | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | APCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | APCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | I&M | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | I&M | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | I&M | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | I&M | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | OPCo | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | OPCo | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | OPCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | OPCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | PSO | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | PSO | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | PSO | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | PSO | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | SWEPCo | Prepaid Expenses and Other Current Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | SWEPCo | Other Noncurrent Assets
Derivative [Line Items]
Total Assets	0	0
Commodity | Designated as Hedging Instrument | SWEPCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Commodity | Designated as Hedging Instrument | SWEPCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	16	36
Interest Rate (USD) | Designated as Hedging Instrument | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	13	35
Interest Rate (USD) | Designated as Hedging Instrument | AEP Texas | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | AEP Texas | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | APCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | APCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | I&M | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | I&M | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | OPCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | OPCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | PSO | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | PSO | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | SWEPCo | Other Current Liabilities
Derivative [Line Items]
Total Liabilities	0	0
Interest Rate (USD) | Designated as Hedging Instrument | SWEPCo | Other Noncurrent Liabilities
Derivative [Line Items]
Total Liabilities	$ 0	$ 0