DERIVATIVES AND HEDGING - Schedule of Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Assets:
Gross Amounts Recognized	$ 1,218.7	$ 1,039.1
Current Risk Management Assets	407.9	210.4
Long-term Risk Management Assets	264.6	289.1
Total Assets	672.5	499.5
Liabilities:
Gross Amounts Recognized	791.3	780.4
Current Risk Management Liabilities, Net	122.7	100.0
Long-term Risk Management Liabilities, Net	186.9	224.4
Total Liabilities	309.6	324.4
Total MTM Derivative Contract Net Assets (Liabilities)	362.9	175.1
Current Risk Management Assets
Assets:
Gross Amounts Recognized	708.6	479.1
Gross Amounts Offset	(300.7)	(268.7)
Long-term Risk Management Assets
Assets:
Gross Amounts Recognized	510.1	560.0
Gross Amounts Offset	(245.5)	(270.9)
Current Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	403.9	351.7
Gross Amounts Offset	(281.2)	(251.7)
Long-term Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	387.4	428.7
Gross Amounts Offset	(200.5)	(204.3)
AEP Texas
Assets:
Gross Amounts Recognized	0.1	0.0
Current Risk Management Assets	0.1	0.0
Long-term Risk Management Assets	0.0	0.0
Total Assets	0.1	0.0
Liabilities:
Gross Amounts Recognized	0.0	0.3
Current Risk Management Liabilities, Net	0.0	0.0
Long-term Risk Management Liabilities, Net	0.0	0.0
Total Liabilities	0.0	0.0
Total MTM Derivative Contract Net Assets (Liabilities)	0.1	0.0
AEP Texas | Current Risk Management Assets
Assets:
Gross Amounts Recognized	0.1	0.0
Gross Amounts Offset	0.0	0.0
AEP Texas | Long-term Risk Management Assets
Assets:
Gross Amounts Recognized	0.0	0.0
Gross Amounts Offset	0.0	0.0
AEP Texas | Current Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	0.0	0.3
Gross Amounts Offset	0.0	(0.3)
AEP Texas | Long-term Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	0.0	0.0
Gross Amounts Offset	0.0	0.0
APCo
Assets:
Gross Amounts Recognized	96.9	42.2
Current Risk Management Assets	92.0	35.7
Long-term Risk Management Assets	2.1	1.4
Total Assets	94.1	37.1
Liabilities:
Gross Amounts Recognized	5.5	7.4
Current Risk Management Liabilities, Net	2.6	2.0
Long-term Risk Management Liabilities, Net	0.1	0.2
Total Liabilities	2.7	2.2
Total MTM Derivative Contract Net Assets (Liabilities)	91.4	34.9
APCo | Current Risk Management Assets
Assets:
Gross Amounts Recognized	94.4	40.2
Gross Amounts Offset	(2.4)	(4.5)
APCo | Long-term Risk Management Assets
Assets:
Gross Amounts Recognized	2.5	2.0
Gross Amounts Offset	(0.4)	(0.6)
APCo | Current Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	5.0	6.6
Gross Amounts Offset	(2.4)	(4.6)
APCo | Long-term Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	0.5	0.8
Gross Amounts Offset	(0.4)	(0.6)
I&M
Assets:
Gross Amounts Recognized	21.0	29.7
Current Risk Management Assets	10.9	18.4
Long-term Risk Management Assets	0.0	0.0
Total Assets	10.9	18.4
Liabilities:
Gross Amounts Recognized	13.4	12.6
Current Risk Management Liabilities, Net	0.8	0.3
Long-term Risk Management Liabilities, Net	0.2	0.4
Total Liabilities	1.0	0.7
Total MTM Derivative Contract Net Assets (Liabilities)	9.9	17.7
I&M | Current Risk Management Assets
Assets:
Gross Amounts Recognized	19.6	28.5
Gross Amounts Offset	(8.7)	(10.1)
I&M | Long-term Risk Management Assets
Assets:
Gross Amounts Recognized	1.4	1.2
Gross Amounts Offset	(1.4)	(1.2)
I&M | Current Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	11.8	10.5
Gross Amounts Offset	(11.0)	(10.2)
I&M | Long-term Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	1.6	2.1
Gross Amounts Offset	(1.4)	(1.7)
OPCo
Assets:
Gross Amounts Recognized	0.0	0.0
Current Risk Management Assets	0.0	0.0
Long-term Risk Management Assets	0.0	0.0
Total Assets	0.0	0.0
Liabilities:
Gross Amounts Recognized	44.3	47.7
Current Risk Management Liabilities, Net	6.3	7.3
Long-term Risk Management Liabilities, Net	38.0	40.2
Total Liabilities	44.3	47.5
Total MTM Derivative Contract Net Assets (Liabilities)	(44.3)	(47.5)
OPCo | Current Risk Management Assets
Assets:
Gross Amounts Recognized	0.0	0.0
Gross Amounts Offset	0.0	0.0
OPCo | Long-term Risk Management Assets
Assets:
Gross Amounts Recognized	0.0	0.0
Gross Amounts Offset	0.0	0.0
OPCo | Current Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	6.3	7.5
Gross Amounts Offset	0.0	(0.2)
OPCo | Long-term Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	38.0	40.2
Gross Amounts Offset	0.0	0.0
PSO
Assets:
Gross Amounts Recognized	68.6	23.9
Current Risk Management Assets	68.1	20.6
Long-term Risk Management Assets	0.0	1.4
Total Assets	68.1	22.0
Liabilities:
Gross Amounts Recognized	17.8	7.8
Current Risk Management Liabilities, Net	15.9	5.8
Long-term Risk Management Liabilities, Net	1.4	0.0
Total Liabilities	17.3	5.8
Total MTM Derivative Contract Net Assets (Liabilities)	50.8	16.2
PSO | Current Risk Management Assets
Assets:
Gross Amounts Recognized	68.6	22.3
Gross Amounts Offset	(0.5)	(1.7)
PSO | Long-term Risk Management Assets
Assets:
Gross Amounts Recognized	0.0	1.6
Gross Amounts Offset	0.0	(0.2)
PSO | Current Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	16.4	7.6
Gross Amounts Offset	(0.5)	(1.8)
PSO | Long-term Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	1.4	0.2
Gross Amounts Offset	0.0	(0.2)
SWEPCo
Assets:
Gross Amounts Recognized	59.8	19.1
Current Risk Management Assets	57.8	18.1
Long-term Risk Management Assets	0.0	0.0
Total Assets	57.8	18.1
Liabilities:
Gross Amounts Recognized	7.4	3.4
Current Risk Management Liabilities, Net	4.4	2.3
Long-term Risk Management Liabilities, Net	1.0	0.0
Total Liabilities	5.4	2.3
Total MTM Derivative Contract Net Assets (Liabilities)	52.4	15.8
SWEPCo | Current Risk Management Assets
Assets:
Gross Amounts Recognized	59.6	19.1
Gross Amounts Offset	(1.8)	(1.0)
SWEPCo | Long-term Risk Management Assets
Assets:
Gross Amounts Recognized	0.2	0.0
Gross Amounts Offset	(0.2)	0.0
SWEPCo | Current Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	6.2	3.4
Gross Amounts Offset	(1.8)	(1.1)
SWEPCo | Long-term Risk Management Liabilities
Liabilities:
Gross Amounts Recognized	1.2	0.0
Gross Amounts Offset	$ (0.2)	$ 0.0