Rate Matters East Companies (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net	$ 62,786.4	$ 60,138.1
AEP Transmission Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net	10,389.5	9,490.9
Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net	11,285.8	11,081.9
Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net	7,001.8	6,899.7
Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net	$ 7,302.1	6,907.0
2017-2019 Virginia Triennial Review [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%
Requested Annual Increase	$ 65.0
Requested Return on Equity	9.90%
Amount Of Increased Depreciation Expense Requested	$ 19.0
Amount of Increase Related to Calculated Shortfall	8.0
Intervenor Calculated Revenue Surplus	$ 23.0
Intervenor Recommended Return on Common Equity	8.75%
Intervenor Calculated Earned Return during Triennial Period	11.12%
Potential Refund due to Intervenor Calculated Earnings above ROE Range	$ 34.0
Approved Return on Common Equity	9.42%
Staff Calculated Revenue Deficiency	$ 17.0
Staff Recommended Return on Common Equity	8.73%
Staff Calculated Return during Triennial Period	9.55%
Impact of 2017 Depreciation Rates on 2018	$ 18.0
Impact of 2017 Depreciation Rates on 2019	20.0
Impact of 2019 Depreciation Rates on 2020	29.0
Transmission Portion of the Impact of 2017 Depreciation Rates on 2018	5.0
Transmission Portion of the Impact of 2017 Depreciation Rates on 2019	5.0
Transmission Portion of the Impact of 2019 Depreciation Rates on 2020	11.0
2017-2019 Virginia Triennial Review [Member] \| Appalachian Power Co [Member] \| Prepaid Pension and OPEB Assets [Member]
Public Utilities, General Disclosures [Line Items]
Recommended Disallowance	114.0
2017-2019 Virginia Triennial Review [Member] \| Appalachian Power Co [Member] \| Storm Expense [Member]
Public Utilities, General Disclosures [Line Items]
Staff Recommended Adjustment to Company's Annual Increase	9.0
2017-2019 Virginia Triennial Review [Member] \| Appalachian Power Co [Member] \| Coal Combustion By-Product Expense [Member]
Public Utilities, General Disclosures [Line Items]
Staff Recommended Adjustment to Company's Annual Increase	12.0
West Virginia ENEC and Vegetation Management Riders [Member]
Public Utilities, General Disclosures [Line Items]
Increase in Rider Rates related to Expanded Net Energy Cost and Vegetation Management	101.0
Refund for Excess ADIT Not Subject to Rate Normalization Requirements	38.0
West Virginia ENEC and Vegetation Management Riders [Member] \| Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Increase in Rider Rates related to Expanded Net Energy Cost and Vegetation Management	81.0
Refund for Excess ADIT Not Subject to Rate Normalization Requirements	31.0
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
Requested Annual Increase	$ 172.0
Requested Return on Equity	10.50%
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
Approved Annual Revenue Increase	$ 77.0
Approved Return on Common Equity	9.70%
Initial Phased in Annual Increase	$ 44.0
Impact on Pretax Earnings due to Loss of Significant Contract	20.0
Kentucky Tax Reform [Member]
Public Utilities, General Disclosures [Line Items]
Refund for Excess ADIT Not Subject to Rate Normalization Requirements	11.0
2020 Kentucky Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	$ 65.0
Requested Return on Equity	10.00%
Requested Recovery Amount of Previously Authorized Deferral	$ 50.0
Amount of Prepaid Pension and OPEB Assets that Intervenor's Recommend a Company Not Earn a Return On	64.0
2020 Ohio Base Rate Case [Member] \| Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	$ 42.0
Requested Return on Equity	10.15%
2019 DIR Audit [Member]
Public Utilities, General Disclosures [Line Items]
DIR Revenue Amount above 2019 Authorized Limit	$ 17.0
Plant Retirement Costs - Unrecovered Plant [Member] \| 2017-2019 Virginia Triennial Review [Member] \| Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Net Book Value of Retired Plants	93.0
Other Asset Impairment Charges	93.0
Virginia Jurisdictional AMR Meters [Member] \| 2017-2019 Virginia Triennial Review [Member] \| Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net	52.0	51.0
Virginia Jurisdictional AMI Meters [Member] \| 2017-2019 Virginia Triennial Review [Member] \| Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment, Net	$ 82.0	$ 75.0
Minimum [Member] \| 2020 Kentucky Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Return on Common Equity	8.93%
Intervenor Recommended Annual Increase	$ 0.0
Maximum [Member] \| 2020 Kentucky Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Return on Common Equity	9.25%
Intervenor Recommended Annual Increase	$ 17.0

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