Rate Matters East Companies (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019		Dec. 31, 2018
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization	$ 18,439.1		$ 17,986.1
Construction Work in Progress	4,944.5		4,393.9
AEP Transmission Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization	336.6	[1]	271.9
Construction Work in Progress	1,785.0		1,578.3
Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization	4,230.8		4,124.4
Construction Work in Progress	556.1		490.2
Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization	3,227.6		3,151.6
Construction Work in Progress	474.1		465.3
Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization	2,238.8		2,218.6
Construction Work in Progress	$ 459.4		$ 432.1
Virginia Legislation Affecting Earnings Reviews [Member]
Public Utilities, General Disclosures [Line Items]
Percent of Excess Earnings Subject to Refund	70.00%
Basis Points Over Authorized Return on Equity Considered Excess Earnings	70.00%
Approved Return on Common Equity	9.42%
Virginia Legislation Affecting Earnings Reviews [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Percent of Excess Earnings Subject to Refund	70.00%
Basis Points Over Authorized Return on Equity Considered Excess Earnings	70.00%
Approved Return on Common Equity	9.42%
Virginia Staff Depreciation Study Request [Member]
Public Utilities, General Disclosures [Line Items]
Potential Increase to Total Annual Depreciation Rates	$ 21.0
Potential Increase to Annual Transmission Depreciation Rates	6.0
Virginia Staff Depreciation Study Request [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Potential Increase to Total Annual Depreciation Rates	21.0
Potential Increase to Annual Transmission Depreciation Rates	6.0
Virginia Tax Reform [Member]
Public Utilities, General Disclosures [Line Items]
Refund Due to Tax Reform	40.0
Refund for Excess ADIT Associated with Certain Depreciable Property	9.0
Refund for Excess ADIT Not Subject to Rate Normalization Requirements	94.0
One Time Refund of Estimated Excess Taxes Collected	22.0
Virginia Tax Reform [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Refund Due to Tax Reform	40.0
Refund for Excess ADIT Associated with Certain Depreciable Property	9.0
Refund for Excess ADIT Not Subject to Rate Normalization Requirements	94.0
One Time Refund of Estimated Excess Taxes Collected	$ 22.0
2018 West Virginia Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Approved Return on Common Equity	9.75%
Refund for Excess ADIT Not Subject to Rate Normalization Requirements	$ 24.0
Amount of Increase Related to Annual Depreciation Rates	32.0
Requested Annual Increase	$ 115.0
Requested Return on Equity	10.22%
Approved Amount of Increase Related to Annual Depreciation Rates	$ 18.0
Regulatory Assets Used to Offset Tax Savings and Excess ADIT Due to Tax Reform	14.0
Adjusted Annual Increase Request due to Tax Reform	95.0
Approved Annual Revenue Increase	$ 44.0
2018 West Virginia Base Rate Case [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Approved Return on Common Equity	9.75%
Refund for Excess ADIT Not Subject to Rate Normalization Requirements	$ 19.0
Amount of Increase Related to Annual Depreciation Rates	28.0
Requested Annual Increase	$ 98.0
Requested Return on Equity	10.22%
Approved Amount of Increase Related to Annual Depreciation Rates	$ 14.0
Regulatory Assets Used to Offset Tax Savings and Excess ADIT Due to Tax Reform	12.0
Adjusted Annual Increase Request due to Tax Reform	80.0
Approved Annual Revenue Increase	36.0
Michigan Tax Reform [Member]
Public Utilities, General Disclosures [Line Items]
Refund for Excess ADIT Associated with Certain Depreciable Property	68.0
Refund for Excess ADIT Not Subject to Rate Normalization Requirements	37.0
Michigan Tax Reform [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Refund for Excess ADIT Associated with Certain Depreciable Property	68.0
Refund for Excess ADIT Not Subject to Rate Normalization Requirements	37.0
2019 Indiana Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Increase Related to Annual Depreciation Rates	78.0
Amount of Increase Related to Annual Depreciation Rates due to Proposed Investments	52.0
Amount of Increase Related to Annual Depreciation Rates due to Increased Depreciation Expense	26.0
Requested Annual Increase	$ 172.0
Requested Return on Equity	10.50%
2019 Indiana Base Rate Case [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Increase Related to Annual Depreciation Rates	$ 78.0
Amount of Increase Related to Annual Depreciation Rates due to Proposed Investments	52.0
Amount of Increase Related to Annual Depreciation Rates due to Increased Depreciation Expense	26.0
Requested Annual Increase	$ 172.0
Requested Return on Equity	10.50%
2019 Michigan Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Increase Related to Annual Depreciation Rates	$ 19.0
Amount of Increase Related to Annual Depreciation Rates due to Proposed Investments	13.0
Amount of Increase Related to Annual Depreciation Rates due to Increased Depreciation Expense	6.0
Amount of Increase Related to Lost Revenue due to Michigan Electric Customer Choice Program	10.0
Requested Annual Increase	$ 58.0
Requested Return on Equity	10.50%
2019 Michigan Base Rate Case [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Increase Related to Annual Depreciation Rates	$ 19.0
Amount of Increase Related to Annual Depreciation Rates due to Proposed Investments	13.0
Amount of Increase Related to Annual Depreciation Rates due to Increased Depreciation Expense	6.0
Amount of Increase Related to Lost Revenue due to Michigan Electric Customer Choice Program	10.0
Requested Annual Increase	$ 58.0
Requested Return on Equity	10.50%
Ohio Electric Security Plan Filing [Member]
Public Utilities, General Disclosures [Line Items]
Return on Common Equity Filed in the Pending Stipulation Agreement	10.00%
Staff Calculated Overspending	$ 10.0
Ohio Electric Security Plan Filing [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Return on Common Equity Filed in the Pending Stipulation Agreement	10.00%
Staff Calculated Overspending	$ 10.0
2016 SEET Filing [Member]
Public Utilities, General Disclosures [Line Items]
Provision for Refund	58.0
2016 SEET Filing [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Provision for Refund	$ 58.0
FERC Transmission Complaint [Member]
Public Utilities, General Disclosures [Line Items]
Approved Return on Common Equity	10.99%
Intervenor Recommended Return on Common Equity	8.32%
Return On Common Equity Per Settlement Agreement	9.85%
Return on Common Equity Inclusive of RTO Per Settlement Agreement	10.35%
RTO Incentive Adder Per Settlement Agreement	0.50%
One Time Refund to Customers Per Settlement Agreement	$ 50.0
Increased Cap on Equity Portion of the Capital Structure Per Settlement Agreement	55.00%
Original Cap on Equity Portion of the Capital Structure Prior to Settlement Agreement	50.00%
Minimum [Member] | Ohio Electric Security Plan Filing [Member]
Public Utilities, General Disclosures [Line Items]
Rate Caps Related to the Distribution Investment Rider Range	$ 215.0
Minimum [Member] | Ohio Electric Security Plan Filing [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Rate Caps Related to the Distribution Investment Rider Range	215.0
Maximum [Member] | Ohio Electric Security Plan Filing [Member]
Public Utilities, General Disclosures [Line Items]
Rate Caps Related to the Distribution Investment Rider Range	290.0
Maximum [Member] | Ohio Electric Security Plan Filing [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Rate Caps Related to the Distribution Investment Rider Range	$ 290.0

[1] Elimination of intercompany interest income/interest expense on affiliated debt arrangement.