FINANCING ACTIVITIES - Issuances of Debt (Details) $ in Millions	9 Months Ended
	Sep. 30, 2025 USD ($)
Debt Instrument [Line Items]
Total Issuances	$ 6,300.0
Junior Subordinated Notes | 5.08% Junior Subordinate Notes
Debt Instrument [Line Items]
Total Issuances	$ 1,100.0
Interest Rate	5.80%
Junior Subordinated Notes | 6.05% Junior Subordinated Notes
Debt Instrument [Line Items]
Total Issuances	$ 900.0
Interest Rate	6.05%
Other Long-term Debt | AEP Texas
Debt Instrument [Line Items]
Total Issuances	$ 400.0
Other Long-term Debt | AEPTCo
Debt Instrument [Line Items]
Total Issuances	141.0
Other Long-term Debt | APCo
Debt Instrument [Line Items]
Total Issuances	425.0
Other Long-term Debt | KPCo
Debt Instrument [Line Items]
Total Issuances	150.0
Other Long-term Debt | Transource Energy
Debt Instrument [Line Items]
Total Issuances	36.6
Other Long-term Debt | WPCo
Debt Instrument [Line Items]
Total Issuances	125.0
Senior Unsecured Notes | AEP Texas | 5.70% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 150.0
Interest Rate	5.70%
Senior Unsecured Notes | AEP Texas | 5.87% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 750.0
Interest Rate	5.85%
Senior Unsecured Notes | AEPTCo
Debt Instrument [Line Items]
Total Issuances	$ 425.0
Interest Rate	5.38%
Senior Unsecured Notes | PSO
Debt Instrument [Line Items]
Total Issuances	$ 800.0
Interest Rate	5.45%
Pollution Control Bonds | APCo | 3.70% Pollution Control Bonds
Debt Instrument [Line Items]
Total Issuances	$ 104.4
Interest Rate	3.70%
Pollution Control Bonds | APCo | 3.30% Pollution Control Bonds
Debt Instrument [Line Items]
Total Issuances	$ 65.3
Interest Rate	3.30%
Pollution Control Bonds | I&M
Debt Instrument [Line Items]
Total Issuances	$ 150.0
Interest Rate	3.70%
Notes Payable | I&M
Debt Instrument [Line Items]
Total Issuances	$ 100.0
Interest Rate	4.89%
Securitization Bonds | KPCo
Debt Instrument [Line Items]
Total Issuances	$ 477.7
Interest Rate	5.30%