Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
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	2.70%	2.60%	2.60%	2.10%
Tax Reform Excess ADIT Reversal	(11.00%)	(11.90%)	(12.10%)	(16.70%)
Production and Investment Tax Credits	(4.60%)	(3.70%)	(4.50%)	(3.60%)
Flow Through	0.50%	0.40%	0.50%	0.10%
AFUDC Equity	(1.50%)	(1.50%)	(1.50%)	(1.50%)
Parent Company Loss Benefit	0.00%	0.00%	0.00%	0.00%
Discrete Tax Adjustments	(7.40%)	(1.70%)	(3.00%)	0.00%
Other	0.10%	0.00%	0.20%	0.30%
Effective Income Tax Rate	(0.20%)	5.20%	3.20%	1.70%
Income Taxes (Textuals) [Abstract]
Proceeds from Income Tax Refunds	$ 20.0
Income Taxes Receivable	$ 95.0		$ 95.0
Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Asset, Income Tax Expense			$ 52.0
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	2.00%	1.40%	1.80%	1.50%
Tax Reform Excess ADIT Reversal	(14.60%)	(6.10%)	(23.40%)	(43.90%)
Production and Investment Tax Credits	(0.50%)	(0.20%)	(0.50%)	(0.50%)
Flow Through	0.20%	0.00%	0.10%	0.10%
AFUDC Equity	(3.50%)	(1.10%)	(3.20%)	(1.30%)
Parent Company Loss Benefit	0.00%	(0.10%)	0.00%	(1.00%)
Discrete Tax Adjustments	(3.60%)	0.00%	(1.60%)	(1.30%)
Other	0.30%	0.20%	0.40%	0.10%
Effective Income Tax Rate	1.30%	15.10%	(5.40%)	(25.30%)
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	2.90%	3.10%	2.90%	3.00%
Tax Reform Excess ADIT Reversal	0.40%	1.40%	0.40%	0.70%
Production and Investment Tax Credits	0.00%	0.00%	0.00%	0.00%
Flow Through	0.50%	0.10%	0.50%	0.20%
AFUDC Equity	(2.60%)	(2.60%)	(2.60%)	(2.50%)
Parent Company Loss Benefit	(0.90%)	(1.30%)	(0.90%)	(1.10%)
Discrete Tax Adjustments	(0.20%)	(0.10%)	(0.10%)	(0.60%)
Other	0.10%	0.30%	(0.10%)	0.00%
Effective Income Tax Rate	21.20%	21.90%	21.10%	20.70%
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	3.10%	3.00%	3.10%	3.30%
Tax Reform Excess ADIT Reversal	(22.00%)	(26.60%)	(20.80%)	(40.20%)
Production and Investment Tax Credits	0.00%	0.00%	0.00%	0.00%
Flow Through	1.60%	3.80%	1.60%	0.70%
AFUDC Equity	(1.10%)	(1.30%)	(1.10%)	(1.10%)
Parent Company Loss Benefit	(3.10%)	(1.10%)	(3.10%)	(1.90%)
Discrete Tax Adjustments	(6.60%)	(2.40%)	(2.30%)	(0.80%)
Other	0.00%	(0.30%)	(0.10%)	(0.10%)
Effective Income Tax Rate	(7.10%)	(3.90%)	(1.70%)	(19.10%)
Income Taxes (Textuals) [Abstract]
Proceeds from Income Tax Refunds	$ 7.0
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	3.40%	(0.10%)	3.40%	1.20%
Tax Reform Excess ADIT Reversal	(16.70%)	(17.30%)	(16.70%)	(17.30%)
Production and Investment Tax Credits	(1.60%)	(2.00%)	(1.60%)	(2.00%)
Flow Through	0.20%	(0.70%)	0.20%	(1.80%)
AFUDC Equity	(0.90%)	(1.70%)	(0.90%)	(1.90%)
Parent Company Loss Benefit	(3.70%)	(1.00%)	(3.70%)	(1.50%)
Discrete Tax Adjustments	2.30%	(1.30%)	1.80%	0.20%
Other	0.00%	0.40%	(0.10%)	0.00%
Effective Income Tax Rate	4.00%	(2.70%)	3.40%	(2.10%)
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	0.80%	0.40%	0.70%	0.70%
Tax Reform Excess ADIT Reversal	(6.70%)	(6.90%)	(8.80%)	(7.40%)
Production and Investment Tax Credits	0.00%	0.00%	0.00%	0.00%
Flow Through	0.90%	1.00%	0.90%	0.70%
AFUDC Equity	(0.90%)	(1.70%)	(0.90%)	(1.00%)
Parent Company Loss Benefit	(0.30%)	0.40%	(0.30%)	(0.70%)
Discrete Tax Adjustments	8.40%	1.70%	2.60%	0.50%
Other	0.30%	(2.00%)	0.20%	0.40%
Effective Income Tax Rate	23.50%	13.90%	15.40%	14.20%
Income Taxes (Textuals) [Abstract]
Proceeds from Income Tax Refunds	$ 9.0
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	4.60%	4.80%	4.60%	4.70%
Tax Reform Excess ADIT Reversal	(20.30%)	(16.50%)	(20.30%)	(18.20%)
Production and Investment Tax Credits	(1.10%)	(1.40%)	(1.10%)	(1.50%)
Flow Through	0.20%	0.70%	0.20%	0.60%
AFUDC Equity	(0.60%)	(0.30%)	(0.60%)	(0.30%)
Parent Company Loss Benefit	(1.70%)	(1.80%)	(1.70%)	(1.80%)
Discrete Tax Adjustments	(0.60%)	0.00%	(0.40%)	0.00%
Other	0.10%	(0.10%)	0.10%	0.10%
Effective Income Tax Rate	1.60%	6.40%	1.80%	4.60%
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	2.40%	2.40%	2.30%	1.80%
Tax Reform Excess ADIT Reversal	(7.30%)	(19.50%)	(11.50%)	(18.70%)
Production and Investment Tax Credits	(0.50%)	(0.90%)	(0.50%)	(0.80%)
Flow Through	(1.20%)	(0.50%)	(1.20%)	(0.60%)
AFUDC Equity	(0.30%)	(0.90%)	(0.30%)	(0.90%)
Parent Company Loss Benefit	(2.00%)	(1.80%)	(1.90%)	(1.50%)
Discrete Tax Adjustments	(0.60%)	0.00%	(0.30%)	(0.20%)
Other	(0.60%)	(0.40%)	(0.40%)	(0.10%)
Effective Income Tax Rate	10.90%	(0.60%)	7.20%	0.00%