DERIVATIVES AND HEDGING - Schedule of Location and Fair Value of Derivative Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Derivative [Line Items]
Total Assets	$ 1,218.7	$ 1,039.1
Total Liabilities	791.3	780.4
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	427.4	258.7
Current Risk Management Assets
Derivative [Line Items]
Total Assets	708.6	479.1
Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	510.1	560.0
Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	403.9	351.7
Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	387.4	428.7
AEP Texas
Derivative [Line Items]
Total Assets	0.1	0.0
Total Liabilities	0.0	0.3
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	0.1	(0.3)
AEP Texas | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.1	0.0
AEP Texas | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
AEP Texas | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.3
AEP Texas | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
APCo
Derivative [Line Items]
Total Assets	96.9	42.2
Total Liabilities	5.5	7.4
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	91.4	34.8
APCo | Current Risk Management Assets
Derivative [Line Items]
Total Assets	94.4	40.2
APCo | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	2.5	2.0
APCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	5.0	6.6
APCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.5	0.8
I&M
Derivative [Line Items]
Total Assets	21.0	29.7
Total Liabilities	13.4	12.6
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	7.6	17.1
I&M | Current Risk Management Assets
Derivative [Line Items]
Total Assets	19.6	28.5
I&M | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	1.4	1.2
I&M | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	11.8	10.5
I&M | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	1.6	2.1
OPCo
Derivative [Line Items]
Total Assets	0.0	0.0
Total Liabilities	44.3	47.7
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	(44.3)	(47.7)
OPCo | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
OPCo | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
OPCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	6.3	7.5
OPCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	38.0	40.2
PSO
Derivative [Line Items]
Total Assets	68.6	23.9
Total Liabilities	17.8	7.8
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	50.8	16.1
PSO | Current Risk Management Assets
Derivative [Line Items]
Total Assets	68.6	22.3
PSO | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	1.6
PSO | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	16.4	7.6
PSO | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	1.4	0.2
SWEPCo
Derivative [Line Items]
Total Assets	59.8	19.1
Total Liabilities	7.4	3.4
Total MTM Derivative Contract Net Assets (Liabilities) Recognized	52.4	15.7
SWEPCo | Current Risk Management Assets
Derivative [Line Items]
Total Assets	59.6	19.1
SWEPCo | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.2	0.0
SWEPCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	6.2	3.4
SWEPCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	1.2	0.0
Commodity | Not Designated as Hedging Instrument | Current Risk Management Assets
Derivative [Line Items]
Total Assets	654.2	425.0
Commodity | Not Designated as Hedging Instrument | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	445.0	475.4
Commodity | Not Designated as Hedging Instrument | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	360.8	304.1
Commodity | Not Designated as Hedging Instrument | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	359.3	390.7
Commodity | Not Designated as Hedging Instrument | AEP Texas | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.1	0.0
Commodity | Not Designated as Hedging Instrument | AEP Texas | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Not Designated as Hedging Instrument | AEP Texas | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.3
Commodity | Not Designated as Hedging Instrument | AEP Texas | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Not Designated as Hedging Instrument | APCo | Current Risk Management Assets
Derivative [Line Items]
Total Assets	94.4	40.2
Commodity | Not Designated as Hedging Instrument | APCo | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	2.5	2.0
Commodity | Not Designated as Hedging Instrument | APCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	5.0	6.6
Commodity | Not Designated as Hedging Instrument | APCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.5	0.8
Commodity | Not Designated as Hedging Instrument | I&M | Current Risk Management Assets
Derivative [Line Items]
Total Assets	19.6	28.5
Commodity | Not Designated as Hedging Instrument | I&M | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	1.4	1.2
Commodity | Not Designated as Hedging Instrument | I&M | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	11.8	10.5
Commodity | Not Designated as Hedging Instrument | I&M | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	1.6	2.1
Commodity | Not Designated as Hedging Instrument | OPCo | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Not Designated as Hedging Instrument | OPCo | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Not Designated as Hedging Instrument | OPCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	6.3	7.5
Commodity | Not Designated as Hedging Instrument | OPCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	38.0	40.2
Commodity | Not Designated as Hedging Instrument | PSO | Current Risk Management Assets
Derivative [Line Items]
Total Assets	68.6	22.3
Commodity | Not Designated as Hedging Instrument | PSO | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	1.6
Commodity | Not Designated as Hedging Instrument | PSO | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	16.4	7.6
Commodity | Not Designated as Hedging Instrument | PSO | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	1.4	0.2
Commodity | Not Designated as Hedging Instrument | SWEPCo | Current Risk Management Assets
Derivative [Line Items]
Total Assets	59.6	19.1
Commodity | Not Designated as Hedging Instrument | SWEPCo | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.2	0.0
Commodity | Not Designated as Hedging Instrument | SWEPCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	6.2	3.4
Commodity | Not Designated as Hedging Instrument | SWEPCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	1.2	0.0
Commodity | Designated as Hedging Instrument | Current Risk Management Assets
Derivative [Line Items]
Total Assets	54.4	54.1
Commodity | Designated as Hedging Instrument | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	65.1	84.6
Commodity | Designated as Hedging Instrument | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	15.7	11.3
Commodity | Designated as Hedging Instrument | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	6.5	2.7
Commodity | Designated as Hedging Instrument | AEP Texas | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | AEP Texas | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | AEP Texas | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | AEP Texas | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | APCo | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | APCo | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | APCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | APCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | I&M | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | I&M | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | I&M | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | I&M | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | OPCo | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | OPCo | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | OPCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | OPCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | PSO | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | PSO | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | PSO | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | PSO | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | SWEPCo | Current Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | SWEPCo | Long-term Risk Management Assets
Derivative [Line Items]
Total Assets	0.0	0.0
Commodity | Designated as Hedging Instrument | SWEPCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Commodity | Designated as Hedging Instrument | SWEPCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	27.4	36.3
Interest Rate (USD) | Designated as Hedging Instrument | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	21.6	35.3
Interest Rate (USD) | Designated as Hedging Instrument | AEP Texas | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | AEP Texas | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | APCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | APCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | I&M | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | I&M | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | OPCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | OPCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | PSO | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | PSO | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | SWEPCo | Current Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	0.0	0.0
Interest Rate (USD) | Designated as Hedging Instrument | SWEPCo | Long-term Risk Management Liabilities
Derivative [Line Items]
Total Liabilities	$ 0.0	$ 0.0