FINANCING ACTIVITIES - Issuances of Debt (Details) $ in Millions	9 Months Ended
	Sep. 30, 2026 USD ($)
Debt Instrument [Line Items]
Total Issuances	$ 7,092
Pollution Control Bonds \| 3.50% Pollution Control Bonds
Debt Instrument [Line Items]
Total Issuances	$ 50
Interest Rate	3.50%
Pollution Control Bonds \| KPCo \| 3.75% Pollution Control Bonds
Debt Instrument [Line Items]
Total Issuances	$ 65
Interest Rate	3.75%
Senior Unsecured Notes \| AEP Texas \| 5.20% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 750
Interest Rate	5.20%
Senior Unsecured Notes \| AEPTCo \| 5.25% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 650
Interest Rate	5.25%
Senior Unsecured Notes \| I&M \| 5.60% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 650
Interest Rate	5.60%
Senior Unsecured Notes \| PSO \| 5.40% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 450
Interest Rate	5.40%
Senior Unsecured Notes \| PSO \| 6.30% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 550
Interest Rate	6.30%
Senior Unsecured Notes \| SWEPCo \| 5.20% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 600
Interest Rate	5.20%
Senior Unsecured Notes \| SWEPCo \| 5.30% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 300
Interest Rate	5.30%
Senior Unsecured Notes \| SWEPCo \| 6.00% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 750
Interest Rate	6.00%
Senior Unsecured Notes \| SWEPCo \| 5.90% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances	$ 500
Interest Rate	5.90%
Other Long-term Debt \| AEPTCo
Debt Instrument [Line Items]
Total Issuances	$ 214
Other Long-term Debt \| KPCo
Debt Instrument [Line Items]
Total Issuances	150
Other Long-term Debt \| Transource Energy
Debt Instrument [Line Items]
Total Issuances	37
Securitization Bonds \| APCo \| 4.96% Securitization Bonds
Debt Instrument [Line Items]
Total Issuances	$ 450
Interest Rate	4.96%
Securitization Bonds \| APCo \| 5.37% Securitization Bonds
Debt Instrument [Line Items]
Total Issuances	$ 326
Interest Rate	5.37%
Securitization Bonds \| APCo \| 5.84% Securitization Bonds
Debt Instrument [Line Items]
Total Issuances	$ 600
Interest Rate	5.84%