FINANCING ACTIVITIES - Issuances of Debt (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Jul. 30, 2026	Jun. 30, 2026
Debt Instrument [Line Items]
Total Issuances		$ 5,088
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 INC. \| 5.20% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances		$ 750
Interest Rate		5.20%
Senior Unsecured Notes \| AEP TRANSMISSION COMPANY, LLC \| 5.25% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances		$ 650
Interest Rate		5.25%
Senior Unsecured Notes \| INDIANA MICHIGAN POWER COMPANY \| 5.60% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances		$ 650
Interest Rate		5.60%
Senior Unsecured Notes \| SOUTHWESTERN ELECTRIC POWER COMPANY \| 5.20% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances		$ 600
Interest Rate		5.20%
Senior Unsecured Notes \| SOUTHWESTERN ELECTRIC POWER COMPANY \| 5.30% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances		$ 300
Interest Rate		5.30%
Senior Unsecured Notes \| SOUTHWESTERN ELECTRIC POWER COMPANY \| 5.90% Senior Unsecured Notes
Debt Instrument [Line Items]
Total Issuances		$ 500
Interest Rate		5.90%
Other Long-term Debt \| AEP TRANSMISSION COMPANY, LLC
Debt Instrument [Line Items]
Total Issuances		$ 124
Other Long-term Debt \| AEP TRANSMISSION COMPANY, LLC \| Subsequent Event
Debt Instrument [Line Items]
Total Issuances	$ 75
Other Long-term Debt \| Transource Energy
Debt Instrument [Line Items]
Total Issuances		23
Other Long-term Debt \| Transource Energy \| Subsequent Event
Debt Instrument [Line Items]
Total Issuances	$ 9
Securitization Bonds \| APPALACHIAN POWER COMPANY \| 4.96% Securitization Bonds
Debt Instrument [Line Items]
Total Issuances		$ 450
Interest Rate		4.96%
Securitization Bonds \| APPALACHIAN POWER COMPANY \| 5.37% Securitization Bonds
Debt Instrument [Line Items]
Total Issuances		$ 326
Interest Rate		5.37%
Securitization Bonds \| APPALACHIAN POWER COMPANY \| 5.84% Securitization Bonds
Debt Instrument [Line Items]
Total Issuances		$ 600
Interest Rate		5.84%