Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%	21.00%	21.00%
State Income Tax, net of Federal Benefit	0.60%	2.70%	1.20%	2.60%
Tax Reform Excess ADIT Reversal	(8.50%)	(11.00%)	(8.90%)	(12.10%)
Production and Investment Tax Credits	(4.70%)	(4.60%)	(4.90%)	(4.50%)
Flow Through	0.00%	0.50%	0.20%	0.50%
AFUDC Equity	(1.20%)	(1.50%)	(1.10%)	(1.50%)
Parent Company Loss Benefit	0.00%	0.00%	0.00%	0.00%
Discrete Tax Adjustments (a)	0.20%	(7.40%)	1.10%	(3.00%)
Other	0.70%	0.10%	0.10%	0.20%
Effective Income Tax Rate	8.10%	(0.20%)	8.70%	3.20%
Income Taxes (Textuals) [Abstract]
Income Taxes Receivable		$ 95.0		$ 95.0
Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Asset, Income Tax Expense			$ 48.0
Income Tax Expense Re-Measurement			20.0
Income Tax Benefit Re-Measurement			$ 1.0
AEP Texas Inc. [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%	21.00%	21.00%
State Income Tax, net of Federal Benefit	0.30%	2.00%	0.30%	1.80%
Tax Reform Excess ADIT Reversal	(6.30%)	(14.60%)	(7.20%)	(23.40%)
Production and Investment Tax Credits	(0.30%)	(0.50%)	(0.30%)	(0.50%)
Flow Through	0.30%	0.20%	0.30%	0.10%
AFUDC Equity	(1.00%)	(3.50%)	(1.10%)	(3.20%)
Parent Company Loss Benefit	(1.10%)	0.00%	(0.70%)	0.00%
Discrete Tax Adjustments (a)	0.00%	(3.60%)	0.00%	(1.60%)
Other	(0.10%)	0.30%	0.00%	0.40%
Effective Income Tax Rate	12.80%	1.30%	12.30%	(5.40%)
AEP Transmission Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%	21.00%	21.00%
State Income Tax, net of Federal Benefit	3.00%	2.90%	2.80%	2.90%
Tax Reform Excess ADIT Reversal	0.30%	0.40%	0.30%	0.40%
Production and Investment Tax Credits	0.00%	0.00%	0.00%	0.00%
Flow Through	0.30%	0.50%	0.30%	0.50%
AFUDC Equity	(2.20%)	(2.60%)	(1.90%)	(2.60%)
Parent Company Loss Benefit	(2.30%)	(0.90%)	(1.90%)	(0.90%)
Discrete Tax Adjustments (a)	0.00%	(0.20%)	0.00%	(0.10%)
Other	0.10%	0.10%	0.00%	(0.10%)
Effective Income Tax Rate	20.20%	21.20%	20.60%	21.10%
Appalachian Power Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%	21.00%	21.00%
State Income Tax, net of Federal Benefit	(0.30%)	3.10%	1.50%	3.10%
Tax Reform Excess ADIT Reversal	(14.20%)	(22.00%)	(15.20%)	(20.80%)
Production and Investment Tax Credits	(0.20%)	0.00%	0.00%	0.00%
Flow Through	0.40%	1.60%	1.70%	1.60%
AFUDC Equity	(1.80%)	(1.10%)	(1.20%)	(1.10%)
Parent Company Loss Benefit	(1.20%)	(3.10%)	(1.30%)	(3.10%)
Discrete Tax Adjustments (a)	0.00%	(6.60%)	0.00%	(2.30%)
Other	0.30%	0.00%	0.10%	(0.10%)
Effective Income Tax Rate	4.00%	(7.10%)	6.60%	(1.70%)
Indiana Michigan Power Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%	21.00%	21.00%
State Income Tax, net of Federal Benefit	1.90%	3.40%	1.60%	3.40%
Tax Reform Excess ADIT Reversal	(16.10%)	(16.70%)	(17.70%)	(16.70%)
Production and Investment Tax Credits	(2.00%)	(1.60%)	(2.20%)	(1.60%)
Flow Through	(2.80%)	0.20%	(3.00%)	0.20%
AFUDC Equity	(1.00%)	(0.90%)	(1.00%)	(0.90%)
Parent Company Loss Benefit	(3.60%)	(3.70%)	(2.80%)	(3.70%)
Discrete Tax Adjustments (a)	0.00%	2.30%	0.00%	1.80%
Other	0.80%	0.00%	0.40%	(0.10%)
Effective Income Tax Rate	(1.80%)	4.00%	(3.70%)	3.40%
Ohio Power Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%	21.00%	21.00%
State Income Tax, net of Federal Benefit	1.20%	0.80%	0.80%	0.70%
Tax Reform Excess ADIT Reversal	(8.90%)	(6.70%)	(9.10%)	(8.80%)
Production and Investment Tax Credits	0.00%	0.00%	0.00%	0.00%
Flow Through	0.60%	0.90%	0.90%	0.90%
AFUDC Equity	(0.30%)	(0.90%)	(0.80%)	(0.90%)
Parent Company Loss Benefit	0.00%	(0.30%)	0.00%	(0.30%)
Discrete Tax Adjustments (a)	0.00%	8.40%	(1.30%)	2.60%
Other	0.00%	0.30%	0.20%	0.20%
Effective Income Tax Rate	13.60%	23.50%	11.70%	15.40%
Public Service Co Of Oklahoma [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%	21.00%	21.00%
State Income Tax, net of Federal Benefit	5.00%	4.60%	4.80%	4.60%
Tax Reform Excess ADIT Reversal	(19.80%)	(20.30%)	(19.80%)	(20.30%)
Production and Investment Tax Credits	(8.90%)	(1.10%)	(8.10%)	(1.10%)
Flow Through	0.70%	0.20%	0.70%	0.20%
AFUDC Equity	(0.20%)	(0.60%)	(0.30%)	(0.60%)
Parent Company Loss Benefit	0.00%	(1.70%)	0.00%	(1.70%)
Discrete Tax Adjustments (a)	0.00%	(0.60%)	(0.90%)	(0.40%)
Other	(0.10%)	0.10%	(0.20%)	0.10%
Effective Income Tax Rate	(2.30%)	1.60%	(2.80%)	1.80%
Southwestern Electric Power Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%	21.00%	21.00%
State Income Tax, net of Federal Benefit	(6.90%)	2.40%	(3.40%)	2.30%
Tax Reform Excess ADIT Reversal	(4.20%)	(7.30%)	(4.30%)	(11.50%)
Production and Investment Tax Credits	(5.40%)	(0.50%)	(4.60%)	(0.50%)
Flow Through	(0.20%)	(1.20%)	(0.20%)	(1.20%)
AFUDC Equity	(0.50%)	(0.30%)	(0.60%)	(0.30%)
Parent Company Loss Benefit	0.70%	(2.00%)	0.00%	(1.90%)
Discrete Tax Adjustments (a)	1.20%	(0.60%)	0.60%	(0.30%)
Other	(0.20%)	(0.60%)	(0.10%)	(0.40%)
Effective Income Tax Rate	5.50%	10.90%	8.40%	7.20%