Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Federal Statutory Tax Rate			35.00%
Effective Income Tax Rate	34.60%	24.30%	36.50%	28.80%
Income Taxes (Textuals) [Abstract]
Pre July 1 2017 Illinois Corporate Income Tax Rate			5.25%
Effective July 1 2017 Illinois Corporate Income Tax Rate			7.00%
Illinois Replacement Tax			2.50%
Total Illinois Corporate Income Tax Rate			7.75%
Increased Total Illinois Corporate Income Tax Rate			9.50%
2011 Audit Issue Settlement [Member]
Valuation Allowance	$ 56		$ 56
AEP Transmission Co [Member]
Federal Statutory Tax Rate			35.00%
Effective Income Tax Rate	34.20%	33.10%	33.90%	32.10%
Appalachian Power Co [Member]
Federal Statutory Tax Rate			35.00%
Effective Income Tax Rate	36.50%	35.90%	36.50%	36.30%
Income Taxes (Textuals) [Abstract]
Pre July 1 2017 Illinois Corporate Income Tax Rate			5.25%
Effective July 1 2017 Illinois Corporate Income Tax Rate			7.00%
Illinois Replacement Tax			2.50%
Total Illinois Corporate Income Tax Rate			7.75%
Increased Total Illinois Corporate Income Tax Rate			9.50%
Indiana Michigan Power Co [Member]
Federal Statutory Tax Rate			35.00%
Effective Income Tax Rate	27.60%	32.90%	29.60%	28.10%
Income Taxes (Textuals) [Abstract]
Pre July 1 2017 Illinois Corporate Income Tax Rate			5.25%
Effective July 1 2017 Illinois Corporate Income Tax Rate			7.00%
Illinois Replacement Tax			2.50%
Total Illinois Corporate Income Tax Rate			7.75%
Increased Total Illinois Corporate Income Tax Rate			9.50%
Ohio Power Co [Member]
Federal Statutory Tax Rate			35.00%
Effective Income Tax Rate	34.90%	34.10%	34.90%	34.50%
Public Service Co Of Oklahoma [Member]
Federal Statutory Tax Rate			35.00%
Effective Income Tax Rate	37.60%	36.20%	37.60%	35.50%
Southwestern Electric Power Co [Member]
Federal Statutory Tax Rate			35.00%
Effective Income Tax Rate	29.70%	23.60%	32.40%	23.70%