INCOME TAXES - Schedule of Effective Income Tax Rate Reconciliation (Details)	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Effective Income Tax Rate Reconciliation [Line Items]
U.S. Federal Statutory Rate	21.00%	21.00%
State and Local Income Taxes, Net	1.10%	1.20%
Tax Reform Excess ADIT Reversal	(3.20%)	(2.60%)
Production and Investment Tax Credits	(10.60%)	(6.50%)
Reversal of Origination Flow-Through	0.80%	0.40%
AFUDC Equity	(1.60%)	(1.20%)
Flow-Through of CAMT	(2.50%)	0.40%
Other	(0.40%)	0.90%
Effective Income Tax Rate	4.60%	13.60%
AEP TEXAS INC.
Effective Income Tax Rate Reconciliation [Line Items]
U.S. Federal Statutory Rate	21.00%	21.00%
State and Local Income Taxes, Net	0.60%	0.20%
Tax Reform Excess ADIT Reversal	(1.50%)	(3.70%)
Production and Investment Tax Credits	(0.10%)	(0.10%)
Reversal of Origination Flow-Through	0.10%	0.10%
AFUDC Equity	(1.60%)	(1.00%)
Flow-Through of CAMT	0.00%	0.00%
Other	(0.10%)	(0.10%)
Effective Income Tax Rate	18.40%	16.40%
AEP TRANSMISSION COMPANY, LLC
Effective Income Tax Rate Reconciliation [Line Items]
U.S. Federal Statutory Rate	21.00%	21.00%
State and Local Income Taxes, Net	2.50%	2.60%
Tax Reform Excess ADIT Reversal	0.20%	0.20%
Production and Investment Tax Credits	0.00%	0.00%
Reversal of Origination Flow-Through	0.20%	0.20%
AFUDC Equity	(1.80%)	(1.70%)
Flow-Through of CAMT	0.00%	0.00%
Other	0.10%	0.00%
Effective Income Tax Rate	22.20%	22.30%
APPALACHIAN POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
U.S. Federal Statutory Rate	21.00%	21.00%
State and Local Income Taxes, Net	(0.20%)	1.10%
Tax Reform Excess ADIT Reversal	(4.70%)	(2.50%)
Production and Investment Tax Credits	(3.50%)	0.00%
Reversal of Origination Flow-Through	2.00%	(0.70%)
AFUDC Equity	(0.90%)	(0.60%)
Flow-Through of CAMT	(8.50%)	1.60%
Other	0.10%	(0.10%)
Effective Income Tax Rate	5.30%	19.80%
INDIANA MICHIGAN POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
U.S. Federal Statutory Rate	21.00%	21.00%
State and Local Income Taxes, Net	3.80%	3.40%
Tax Reform Excess ADIT Reversal	(2.40%)	(3.60%)
Production and Investment Tax Credits	(7.90%)	(11.70%)
Reversal of Origination Flow-Through	1.40%	1.90%
AFUDC Equity	(0.70%)	(0.50%)
Flow-Through of CAMT	0.00%	0.00%
Other	(0.30%)	(0.10%)
Effective Income Tax Rate	14.90%	10.40%
OHIO POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
U.S. Federal Statutory Rate	21.00%	21.00%
State and Local Income Taxes, Net	1.00%	1.90%
Tax Reform Excess ADIT Reversal	(11.40%)	(4.10%)
Production and Investment Tax Credits	0.00%	0.00%
Reversal of Origination Flow-Through	0.60%	0.90%
AFUDC Equity	(1.80%)	(1.90%)
Flow-Through of CAMT	0.00%	0.00%
Other	(0.10%)	0.30%
Effective Income Tax Rate	9.30%	18.10%
PUBLIC SERVICE COMPANY OF OKLAHOMA
Effective Income Tax Rate Reconciliation [Line Items]
U.S. Federal Statutory Rate	21.00%	21.00%
State and Local Income Taxes, Net	3.20%	2.90%
Tax Reform Excess ADIT Reversal	1.70%	(3.60%)
Production and Investment Tax Credits	135.00%	(27.60%)
Reversal of Origination Flow-Through	(0.10%)	0.10%
AFUDC Equity	0.40%	(0.50%)
Flow-Through of CAMT	0.00%	0.00%
Other	(1.20%)	(0.10%)
Effective Income Tax Rate	160.00%	(7.80%)
SOUTHWESTERN ELECTRIC POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
U.S. Federal Statutory Rate	21.00%	21.00%
State and Local Income Taxes, Net	(37.50%)	(1.40%)
Tax Reform Excess ADIT Reversal	(25.00%)	(3.10%)
Production and Investment Tax Credits	(562.50%)	(31.20%)
Reversal of Origination Flow-Through	0.00%	0.70%
AFUDC Equity	(12.50%)	(1.40%)
Flow-Through of CAMT	0.00%	0.00%
Other	4.00%	0.70%
Effective Income Tax Rate	(612.50%)	(14.70%)