FINANCING ACTIVITIES - Repayments and Retirements of Debt (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Oct. 29, 2025	Sep. 30, 2025	Sep. 30, 2024
Debt Instrument [Line Items]
Principal Amount Paid		$ 2,803.8	$ 1,969.1
5.70% Junior Subordinated Notes | Junior Subordinated Notes
Debt Instrument [Line Items]
Principal Amount Paid		$ 850.0
Interest Rate		5.70%
AEP Texas
Debt Instrument [Line Items]
Principal Amount Paid		$ 474.5	256.5
AEP Texas | Variable Other Long-term Debt | Other Long-term Debt
Debt Instrument [Line Items]
Principal Amount Paid		400.0
AEP Texas | 2.06% Securitization Bonds | Securitization Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 10.3
Interest Rate		2.06%
AEP Texas | 2.29% Securitization Bonds | Securitization Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 14.2
Interest Rate		2.29%
AEP Texas | 3.75% Senior Unsecured Notes | Senior Unsecured Notes
Debt Instrument [Line Items]
Principal Amount Paid		$ 50.0
Interest Rate		3.75%
AEPTCo
Debt Instrument [Line Items]
Principal Amount Paid		$ 90.0	0.0
AEPTCo | Senior Unsecured Notes
Debt Instrument [Line Items]
Interest Rate		5.38%
AEPTCo | 3.66% Senior Unsecured Notes | Senior Unsecured Notes
Debt Instrument [Line Items]
Principal Amount Paid		$ 50.0
Interest Rate		3.66%
AEPTCo | 3.76% Senior Unsecured Notes | Senior Unsecured Notes
Debt Instrument [Line Items]
Principal Amount Paid		$ 40.0
Interest Rate		3.76%
APCo
Debt Instrument [Line Items]
Principal Amount Paid		$ 498.3	413.5
APCo | 13.72% Other Long-term Debt | Other Long-term Debt
Debt Instrument [Line Items]
Principal Amount Paid		$ 0.1
Interest Rate		13.72%
APCo | 3.75% Pollution Control Bonds | Pollution Control Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 104.4
Interest Rate		3.75%
APCo | 1.00% Pollution Control Bonds | Pollution Control Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 65.4
Interest Rate		1.00%
APCo | 3.77% Securitization Bonds | Securitization Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 28.4
Interest Rate		3.77%
APCo | 3.40% Senior Unsecured Notes | Senior Unsecured Notes
Debt Instrument [Line Items]
Principal Amount Paid		$ 300.0
Interest Rate		3.40%
I&M
Debt Instrument [Line Items]
Principal Amount Paid		$ 269.9	76.1
I&M | Pollution Control Bonds
Debt Instrument [Line Items]
Interest Rate		3.70%
I&M | Notes Payable
Debt Instrument [Line Items]
Interest Rate		4.89%
I&M | Notes Payable | Subsequent Event
Debt Instrument [Line Items]
Principal Amount Paid	$ 8.0
I&M | 0.93% Notes Payable | Notes Payable
Debt Instrument [Line Items]
Principal Amount Paid		$ 3.9
Interest Rate		0.93%
I&M | Variable Note Payable | Notes Payable
Debt Instrument [Line Items]
Principal Amount Paid		$ 1.1
I&M | 3.44% Notes Payable | Notes Payable
Debt Instrument [Line Items]
Principal Amount Paid		$ 8.4
Interest Rate		3.44%
I&M | 5.93% Notes Payable | Notes Payable
Debt Instrument [Line Items]
Principal Amount Paid		$ 13.2
Interest Rate		5.93%
I&M | 6.41% Notes Payable | Notes Payable
Debt Instrument [Line Items]
Principal Amount Paid		$ 24.6
Interest Rate		6.41%
I&M | 6.01% Notes Payable | Notes Payable
Debt Instrument [Line Items]
Principal Amount Paid		$ 15.4
Interest Rate		6.01%
I&M | 4.89% Notes Payable | Notes Payable
Debt Instrument [Line Items]
Principal Amount Paid		$ 13.1
Interest Rate		4.89%
I&M | 6.00% Other Long-term Debt | Other Long-term Debt
Debt Instrument [Line Items]
Principal Amount Paid		$ 0.2
Interest Rate		6.00%
I&M | 3.05% Pollution Control Bonds | Pollution Control Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 100.0
Interest Rate		3.05%
I&M | 2.75% Pollution Control Bonds | Pollution Control Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 50.0
Interest Rate		2.75%
I&M | 0.75% Pollution Control Bonds | Pollution Control Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 40.0
Interest Rate		0.75%
PSO
Debt Instrument [Line Items]
Principal Amount Paid		$ 125.4	0.4
PSO | Senior Unsecured Notes
Debt Instrument [Line Items]
Interest Rate		5.45%
PSO | 3.00% Other Long-term Debt | Other Long-term Debt
Debt Instrument [Line Items]
Principal Amount Paid		$ 0.4
Interest Rate		3.00%
PSO | 3.17% Senior Unsecured Notes | Senior Unsecured Notes
Debt Instrument [Line Items]
Principal Amount Paid		$ 125.0
Interest Rate		3.17%
SWEPCo
Debt Instrument [Line Items]
Principal Amount Paid		$ 11.1	$ 0.0
SWEPCo | 4.88% Securitization Bonds | Securitization Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 11.1
Interest Rate		4.88%
AEGCo | 1.35% Pollution Control Bonds | Pollution Control Bonds
Debt Instrument [Line Items]
Principal Amount Paid		$ 45.0
Interest Rate		1.35%
KPCo | Securitization Bonds
Debt Instrument [Line Items]
Interest Rate		5.30%
KPCo | Variable Other Long-term Debt | Other Long-term Debt
Debt Instrument [Line Items]
Principal Amount Paid		$ 150.0
Transource Energy | 2.75 % Senior Unsecured Notes | Senior Unsecured Notes
Debt Instrument [Line Items]
Principal Amount Paid		$ 2.6
Interest Rate		2.75%
WPCo | 6.89% Notes Payable | Notes Payable
Debt Instrument [Line Items]
Principal Amount Paid		$ 15.0
Interest Rate		6.89%
WPCo | 3.70% Senior Unsecured Notes | Senior Unsecured Notes
Debt Instrument [Line Items]
Principal Amount Paid		$ 122.0
Interest Rate		3.70%