Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Federal Statutory Income Tax Rate	21.00%	21.00%
Effective Income Tax Rate	7.20%	18.30%
Amortization of Excess ADIT [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Amount	$ 66
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(10.80%)
AEP Texas Inc. [Member]
Federal Statutory Income Tax Rate	21.00%	21.00%
Effective Income Tax Rate	10.40%	16.30%
AEP Texas Inc. [Member] | Amortization of Excess ADIT [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Amount	$ 1
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(3.90%)
AEP Texas Inc. [Member] | Parent Company Loss Benefit [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(2.20%)
AEP Transmission Co [Member]
Federal Statutory Income Tax Rate	21.00%	21.00%
Effective Income Tax Rate	20.90%	20.70%
Appalachian Power Co [Member]
Federal Statutory Income Tax Rate	21.00%	21.00%
Effective Income Tax Rate	(22.00%)	18.20%
Appalachian Power Co [Member] | Amortization of Excess ADIT [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Amount	$ 41
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(37.90%)
Indiana Michigan Power Co [Member]
Federal Statutory Income Tax Rate	21.00%	21.00%
Effective Income Tax Rate	(2.80%)	16.20%
Indiana Michigan Power Co [Member] | Amortization of Excess ADIT [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Amount	$ 13
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(13.70%)
Indiana Michigan Power Co [Member] | Flow-Through Items [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(6.10%)
Ohio Power Co [Member]
Federal Statutory Income Tax Rate	21.00%	21.00%
Effective Income Tax Rate	13.40%	20.50%
Ohio Power Co [Member] | Amortization of Excess ADIT [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Amount	$ 9
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(6.00%)
Public Service Co Of Oklahoma [Member]
Federal Statutory Income Tax Rate	21.00%	21.00%
Effective Income Tax Rate	0.60%	16.30%
Public Service Co Of Oklahoma [Member] | Amortization of Excess ADIT [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Amount	$ 1
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(16.90%)
Southwestern Electric Power Co [Member]
Federal Statutory Income Tax Rate	21.00%	21.00%
Effective Income Tax Rate	2.40%	18.40%
Southwestern Electric Power Co [Member] | Amortization of Excess ADIT [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Amount	$ 3
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(11.30%)
Southwestern Electric Power Co [Member] | State Tax Expense [Member]
Effective Income Tax Rate Reconciliation, Variance Explanation, Percent	(1.30%)