Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 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	0.80%		2.70%	1.60%	2.60%
Tax Reform Excess ADIT Reversal	(9.10%)		(16.40%)	(9.10%)	(12.80%)
Production and Investment Tax Credits	(4.70%)		(4.60%)	(5.10%)	(4.40%)
Flow Through	0.40%		0.50%	0.30%	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	2.90%			1.70%	0.00%
Other	(0.50%)		0.70%	(0.20%)	0.10%
Effective Income Tax Rate	9.60%		2.40%	9.10%	5.50%
Income Taxes (Textuals) [Abstract]
Income Taxes Receivable		$ 95
Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Asset, Income Tax Expense		$ 48
Income Tax Expense Re-Measurement	$ 20
Income Tax Benefit Re-Measurement	$ 1
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	(0.40%)		1.80%	0.30%	1.70%
Tax Reform Excess ADIT Reversal	(7.90%)		(57.90%)	(7.90%)	(30.40%)
Production and Investment Tax Credits	(0.30%)		(0.50%)	(0.30%)	(0.40%)
Flow Through	0.40%		0.20%	0.30%	0.10%
AFUDC Equity	(0.90%)		(3.30%)	(1.10%)	(2.90%)
Parent Company Loss Benefit	(0.70%)		0.20%	(0.40%)	0.00%
Discrete Tax Adjustments	0.00%			0.00%	0.00%
Other	(0.20%)		0.00%	0.00%	0.10%
Effective Income Tax Rate	11.00%		(38.50%)	11.90%	(10.80%)
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	2.60%		2.90%	2.70%	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	0.40%		0.50%	0.30%	0.50%
AFUDC Equity	(1.70%)		(2.60%)	(1.70%)	(2.60%)
Parent Company Loss Benefit	(1.70%)		(0.80%)	(1.80%)	(0.90%)
Discrete Tax Adjustments	0.00%			0.00%	0.00%
Other	(0.10%)		(0.60%)	0.00%	(0.20%)
Effective Income Tax Rate	20.80%		20.80%	20.80%	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	0.90%		3.20%	2.40%	3.10%
Tax Reform Excess ADIT Reversal	(11.80%)		(32.50%)	(15.70%)	(20.20%)
Production and Investment Tax Credits	0.00%		0.00%	0.00%	0.00%
Flow Through	3.30%		1.90%	2.20%	1.60%
AFUDC Equity	(0.50%)		(1.30%)	(0.90%)	(1.10%)
Parent Company Loss Benefit	1.00%		(2.90%)	(1.40%)	(3.10%)
Discrete Tax Adjustments	0.00%			0.00%	0.00%
Other	0.00%		(0.20%)	0.10%	0.00%
Effective Income Tax Rate	13.90%		(10.80%)	7.70%	1.30%
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	1.60%		3.60%	1.40%	3.40%
Tax Reform Excess ADIT Reversal	(20.40%)		(12.60%)	(19.00%)	(16.70%)
Production and Investment Tax Credits	(3.30%)		(1.20%)	(2.30%)	(1.60%)
Flow Through	(5.80%)		0.10%	(3.00%)	0.20%
AFUDC Equity	(2.20%)		(0.70%)	(1.00%)	(0.90%)
Parent Company Loss Benefit	(1.70%)		(3.30%)	(2.10%)	(3.70%)
Discrete Tax Adjustments	0.00%			0.00%	1.60%
Other	(0.50%)		0.00%	(0.30%)	(0.10%)
Effective Income Tax Rate	(11.30%)		6.90%	(5.30%)	3.20%
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	0.70%		0.70%	0.70%	0.70%
Tax Reform Excess ADIT Reversal	(8.60%)		(9.30%)	(9.10%)	(9.70%)
Production and Investment Tax Credits	0.00%		0.00%	0.00%	0.00%
Flow Through	1.00%		0.90%	1.10%	0.90%
AFUDC Equity	(0.90%)		(0.80%)	(1.00%)	(0.90%)
Parent Company Loss Benefit	0.00%		(0.40%)	0.00%	(0.30%)
Discrete Tax Adjustments	0.00%			(1.80%)	0.00%
Other	(0.10%)		0.10%	(0.10%)	0.10%
Effective Income Tax Rate	13.10%		12.20%	10.80%	11.80%
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	4.40%		4.60%	4.40%	4.60%
Tax Reform Excess ADIT Reversal	(20.10%)		(20.90%)	(19.90%)	(20.30%)
Production and Investment Tax Credits	(6.80%)		(1.20%)	(6.60%)	(1.10%)
Flow Through	0.80%		0.30%	0.80%	0.20%
AFUDC Equity	(0.70%)		(0.60%)	(0.70%)	(0.60%)
Parent Company Loss Benefit	0.00%		(1.80%)	0.00%	(1.70%)
Discrete Tax Adjustments	(2.60%)			(2.80%)	0.00%
Other	(0.10%)		0.10%	0.00%	0.10%
Effective Income Tax Rate	(4.10%)		1.50%	(3.80%)	2.20%
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	1.90%		2.10%	0.30%	2.20%
Tax Reform Excess ADIT Reversal	(1.90%)		(6.30%)	(4.30%)	(17.00%)
Production and Investment Tax Credits	(1.40%)		(0.40%)	(3.70%)	(0.40%)
Flow Through	0.50%		(1.20%)	(0.20%)	(1.10%)
AFUDC Equity	(0.80%)		(0.30%)	(0.60%)	(0.30%)
Parent Company Loss Benefit	(1.90%)		(1.70%)	(0.80%)	(1.80%)
Discrete Tax Adjustments	0.00%			0.00%	0.00%
Other	(1.20%)		(1.30%)	(0.40%)	(0.30%)
Effective Income Tax Rate	16.20%		11.90%	11.30%	2.30%