Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%
State Income Tax, net of Federal benefit	2.50%	2.10%
Tax Reform Excess ADIT Reversal	(9.40%)	(13.60%)
Production and Investment Tax Credits	(4.30%)	(2.20%)
Flow Through	0.50%	(0.20%)
AFUDC Equity	(1.40%)	(1.40%)
Parent Company Loss	0.00%	0.00%
Discrete Tax Adjustments	0.00%	1.70%
Other	(0.40%)	(0.20%)
Effective Income Tax Rate	8.50%	7.20%
Income Taxes (Textuals) [Abstract]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	$ 20
AEP Texas Inc. [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%
State Income Tax, net of Federal benefit	1.50%	1.50%
Tax Reform Excess ADIT Reversal	(6.20%)	(7.60%)
Production and Investment Tax Credits	(0.40%)	(1.00%)
Flow Through	0.10%	0.30%
AFUDC Equity	(2.60%)	(1.60%)
Parent Company Loss	(0.20%)	(2.30%)
Discrete Tax Adjustments	0.00%	0.00%
Other	0.30%	0.10%
Effective Income Tax Rate	13.50%	10.40%
AEP Transmission Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%
State Income Tax, net of Federal benefit	2.90%	2.90%
Tax Reform Excess ADIT Reversal	0.40%	0.40%
Production and Investment Tax Credits	0.00%	0.00%
Flow Through	0.50%	0.20%
AFUDC Equity	(2.60%)	(2.50%)
Parent Company Loss	(0.90%)	(1.00%)
Discrete Tax Adjustments	0.00%	0.00%
Other	0.00%	(0.10%)
Effective Income Tax Rate	21.30%	20.90%
Appalachian Power Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%
State Income Tax, net of Federal benefit	3.00%	3.40%
Tax Reform Excess ADIT Reversal	(13.00%)	(42.20%)
Production and Investment Tax Credits	0.00%	0.00%
Flow Through	1.50%	(0.90%)
AFUDC Equity	(1.00%)	(1.00%)
Parent Company Loss	(3.30%)	(2.40%)
Discrete Tax Adjustments	0.00%	0.40%
Other	0.10%	(0.30%)
Effective Income Tax Rate	8.30%	(22.00%)
Income Taxes (Textuals) [Abstract]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	$ 7
Indiana Michigan Power Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%
State Income Tax, net of Federal benefit	3.20%	2.00%
Tax Reform Excess ADIT Reversal	(19.60%)	(17.40%)
Production and Investment Tax Credits	(1.90%)	(2.00%)
Flow Through	0.20%	(2.40%)
AFUDC Equity	(1.10%)	(1.90%)
Parent Company Loss	(3.90%)	(1.80%)
Discrete Tax Adjustments	2.70%	0.00%
Other	(0.20%)	(0.30%)
Effective Income Tax Rate	0.40%	(2.80%)
Ohio Power Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%
State Income Tax, net of Federal benefit	0.70%	0.90%
Tax Reform Excess ADIT Reversal	(10.20%)	(7.60%)
Production and Investment Tax Credits	0.00%	0.00%
Flow Through	1.00%	0.70%
AFUDC Equity	(1.00%)	(0.70%)
Parent Company Loss	(0.10%)	(1.10%)
Discrete Tax Adjustments	0.00%	0.00%
Other	0.00%	0.20%
Effective Income Tax Rate	11.40%	13.40%
Income Taxes (Textuals) [Abstract]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	$ 9
Public Service Co Of Oklahoma [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%
State Income Tax, net of Federal benefit	4.60%	4.60%
Tax Reform Excess ADIT Reversal	(23.10%)	(21.90%)
Production and Investment Tax Credits	(1.30%)	(1.70%)
Flow Through	0.60%	0.60%
AFUDC Equity	(0.70%)	(0.40%)
Parent Company Loss	(2.20%)	(1.80%)
Discrete Tax Adjustments	0.00%	0.00%
Other	0.10%	0.20%
Effective Income Tax Rate	(1.00%)	0.60%
Southwestern Electric Power Co [Member]
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. Federal Statutory Rate	21.00%	21.00%
State Income Tax, net of Federal benefit	2.70%	0.20%
Tax Reform Excess ADIT Reversal	(94.70%)	(17.00%)
Production and Investment Tax Credits	(0.50%)	(0.80%)
Flow Through	(1.00%)	(0.90%)
AFUDC Equity	(0.40%)	(1.10%)
Parent Company Loss	(2.40%)	(0.50%)
Discrete Tax Adjustments	0.00%	0.00%
Other	7.20%	1.50%
Effective Income Tax Rate	(68.10%)	2.40%