Rate Matters East Companies (Details)	1 Months Ended	3 Months Ended
	Apr. 30, 2018 USD ($)	Mar. 31, 2018 USD ($) MW	Dec. 31, 2017 USD ($)
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		$ 17,431,200,000	$ 17,167,000,000
Construction Work in Progress		4,759,400,000	4,120,700,000
AEP Transmission Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		192,700,000	170,400,000
Construction Work in Progress		1,512,600,000	1,312,700,000
Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		3,956,800,000	3,896,400,000
Construction Work in Progress		558,800,000	483,000,000
Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		3,073,100,000	3,024,200,000
Construction Work in Progress		503,500,000	460,200,000
Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		2,205,700,000	2,184,800,000
Construction Work in Progress		432,000,000	$ 410,100,000
Virginia Legislation Affecting Earnings Reviews [Member]
Public Utilities, General Disclosures [Line Items]
Fuel Expenses Not to be Recovered		10,000,000
Reduction in Annual Base Rates		50,000,000
EnergyEfficiencyProgramsToBeRequestedFromTheVirginiaSCCThroughJuly,2028dollars		$ 140,000,000
EnergyEfficiencyProgramsToBeRequestedFromTheVirginiaSCCThroughJuly,2028MWs | MW		200
Virginia Legislation Affecting Earnings Reviews [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Fuel Expenses Not to be Recovered		$ 10,000,000
Reduction in Annual Base Rates		50,000,000
EnergyEfficiencyProgramsToBeRequestedFromTheVirginiaSCCThroughJuly,2028dollars		$ 140,000,000
EnergyEfficiencyProgramsToBeRequestedFromTheVirginiaSCCThroughJuly,2028MWs | MW		200
2017 Indiana Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		$ 263,000,000
Requested Return on Equity		10.60%
Amount Of Annual Reduction To Customer Bills Through Credit Adjustment Rider		$ 23,000,000
Amount Of Increased Depreciation Expense Requested		78,000,000
Amount of Increase Related to Amortization of Regulatory Assets		11,000,000
Adjusted Annual Increase Request due to Tax Reform		191,000,000
Setlled Annual Increase		$ 97,000,000
Settled Return on Common Equity		9.95%
Original Sharing of Off-System Sales Margins		50.00%
Settled Sharing of Off-System Sales Margins		95.00%
Refund for Impact of Tax Reform		$ 4,000,000
2017 Indiana Base Rate Case [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		$ 263,000,000
Requested Return on Equity		10.60%
Amount Of Annual Reduction To Customer Bills Through Credit Adjustment Rider		$ 23,000,000
Amount Of Increased Depreciation Expense Requested		78,000,000
Amount of Increase Related to Amortization of Regulatory Assets		11,000,000
Adjusted Annual Increase Request due to Tax Reform		191,000,000
Setlled Annual Increase		$ 97,000,000
Settled Return on Common Equity		9.95%
Original Sharing of Off-System Sales Margins		50.00%
Settled Sharing of Off-System Sales Margins		95.00%
Refund for Impact of Tax Reform		$ 4,000,000
2017 Michigan Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		$ 52,000,000
Requested Return on Equity		10.60%
Amount Of Increased Depreciation Expense Requested		$ 23,000,000
Amount of Increase Related to Amortization of Regulatory Assets		4,000,000
ALJ Recommended Annual Increase		49,000,000
Cost of New Entry Value		$ 289
ALJ Recommended Return on Common Equity		9.80%
Reduced Capacity Charge Pretax Loss		$ 9,000,000
Alternate Supplier Cap		10.00%
2017 Michigan Base Rate Case [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase		$ 52,000,000
Requested Return on Equity		10.60%
Amount Of Increased Depreciation Expense Requested		$ 23,000,000
Amount of Increase Related to Amortization of Regulatory Assets		4,000,000
ALJ Recommended Annual Increase		49,000,000
Cost of New Entry Value		$ 289
ALJ Recommended Return on Common Equity		9.80%
Reduced Capacity Charge Pretax Loss		$ 9,000,000
Alternate Supplier Cap		10.00%
Rockport Plant, Unit 2 Selective Catalytic Reduction [Member]
Public Utilities, General Disclosures [Line Items]
Projected Capital Costs		$ 274,000,000
Construction Work in Progress		28,000,000
Approved Capital Costs		274,000,000
Rockport Plant, Unit 2 Selective Catalytic Reduction [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Projected Capital Costs		274,000,000
Construction Work in Progress		28,000,000
Approved Capital Costs		274,000,000
2017 Kentucky Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
KPSC Order Annual Revenue Increase		$ 12,000,000
KPSC Order Return on Common Equity		9.70%
KPSC Order Annual Revenue Reduction due to Tax Reform		$ 14,000,000
KPSC Order Deferral of Rockport Plant Unit Power Agreement Expenses		$ 50,000,000
Recovery/Return of certain PJM OATT Expenses Above/Below Corresponding Level Recovered in Rates		80.00%
KPCo Request for Additional Revenue Increase		$ 2,300,000
Ohio Electric Security Plan Filing [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Return On Common Equity Range		9.30%
PUCO Approved Reduced Customer Credits		$ 15,000,000
Solar Energy Projects To Be Developed And Implemented By 2021 As Proposed In Stipulation Agreement | MW		400
Wind Energy Projects To Be Developed And Implemented By 2021 As Proposed In Stipulation Agreement | MW		500
Percentage of Output to be Received from Solar and Wind Projects as Proposed in Stipulation Agreement		100.00%
Maximum Ownership Percentage of Solar and Wind Projects as Proposed in Stipulation Agreement		50.00%
Return on Common Equity Proposed in the Amended ESP Filing		10.41%
Return on Common Equity Filed in the Pending Stipulation Agreement		10.00%
Ohio Electric Security Plan Filing [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Return On Common Equity Range		9.30%
PUCO Approved Reduced Customer Credits		$ 15,000,000
Solar Energy Projects To Be Developed And Implemented By 2021 As Proposed In Stipulation Agreement | MW		400
Wind Energy Projects To Be Developed And Implemented By 2021 As Proposed In Stipulation Agreement | MW		500
Percentage of Output to be Received from Solar and Wind Projects as Proposed in Stipulation Agreement		100.00%
Maximum Ownership Percentage of Solar and Wind Projects as Proposed in Stipulation Agreement		50.00%
Return on Common Equity Proposed in the Amended ESP Filing		10.41%
Return on Common Equity Filed in the Pending Stipulation Agreement		10.00%
2016 SEET Filing [Member]
Public Utilities, General Disclosures [Line Items]
Provision for Refund		$ 58,000,000
Intervenor Recommended Refund to Customers		53,000,000
2016 SEET Filing [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Provision for Refund		58,000,000
Intervenor Recommended Refund to Customers		$ 53,000,000
FERC Transmission Complaint [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Return On Common Equity Range		8.32%
Approved Return on Common Equity		10.99%
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		$ 50,000,000
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%
Subsequent Event [Member] | 2017 Michigan Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Approved Annual Revenue Increase	$ 49,000,000
Approved Return on Common Equity	9.90%
Subsequent Event [Member] | 2017 Michigan Base Rate Case [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Approved Annual Revenue Increase	$ 49,000,000
Approved Return on Common Equity	9.90%
Subsequent Event [Member] | FERC Transmission Complaint [Member]
Public Utilities, General Disclosures [Line Items]
Second Intervenor Recommended Return on Common Equity	8.48%
Second Intervenor Recommended One Time Refund to Customers	$ 184,000,000
FERC Trial Staff Recommended Return on Common Equity	8.41%
FERC Trial Staff Recommended One Time Refund to Customers	$ 175,000,000
Minimum [Member] | 2017 Indiana Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Annual Increase		$ 125,000,000
Intervenor Recommended Return On Common Equity Range		8.65%
Minimum [Member] | 2017 Indiana Base Rate Case [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Annual Increase		$ 125,000,000
Intervenor Recommended Return On Common Equity Range		8.65%
Minimum [Member] | Ohio Electric Security Plan Filing [Member]
Public Utilities, General Disclosures [Line Items]
Rate Caps Related to the Distribution Investment Rider Range		$ 215,000,000
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		215,000,000
Maximum [Member] | 2017 Indiana Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Annual Increase		$ 152,000,000
Intervenor Recommended Return On Common Equity Range		9.10%
Maximum [Member] | 2017 Indiana Base Rate Case [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended Annual Increase		$ 152,000,000
Intervenor Recommended Return On Common Equity Range		9.10%
Maximum [Member] | Ohio Electric Security Plan Filing [Member]
Public Utilities, General Disclosures [Line Items]
Rate Caps Related to the Distribution Investment Rider Range		$ 290,000,000
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		$ 290,000,000