Rate Matters - East Companies (Details)	6 Months Ended
	Jun. 30, 2018 USD ($) MW	Dec. 31, 2017 USD ($)
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization	$ 17,571,400,000	$ 17,167,000,000
Construction Work in Progress	4,630,300,000	4,120,700,000
Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization	4,028,800,000	3,896,400,000
Construction Work in Progress	602,100,000	483,000,000
Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization	3,057,300,000	3,024,200,000
Construction Work in Progress	404,300,000	460,200,000
Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization	2,218,600,000	2,184,800,000
Construction Work in Progress	445,200,000	$ 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
Energy Efficiency Programs to be Requested from the Virginia SCC Through July, 2028 Dollars	$ 140,000,000
Energy Efficiency Programs to be Requested from the Virginia SCC Through July, 2028 MWs | 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
Energy Efficiency Programs to be Requested from the Virginia SCC Through July, 2028 Dollars	$ 140,000,000
Energy Efficiency Programs to be Requested from the Virginia SCC Through July, 2028 MWs | MW	200
2018 West Virginia Base Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	$ 115,000,000
Requested Return on Common Equity	10.22%
Amount of Increase Related to Annual Depreciation Rates	$ 32,000,000
2018 West Virginia Base Rate Case [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	$ 98,000,000
Requested Return on Common Equity	10.22%
Amount of Increase Related to Annual Depreciation Rates	$ 28,000,000
Indiana Base Rate Case - 2017 [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	$ 263,000,000
Requested Return on Common Equity	10.60%
Amount Of Annual Reduction To Customer Bills Through Credit Adjustment Rider	$ 23,000,000
Amount of Increase Related to Annual Depreciation Rates	78,000,000
Amount of Increase Related to Amortization of Regulatory Assets	11,000,000
Settled 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
Indiana Base Rate Case - 2017 [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	$ 263,000,000
Requested Return on Common Equity	10.60%
Amount Of Annual Reduction To Customer Bills Through Credit Adjustment Rider	$ 23,000,000
Amount of Increase Related to Annual Depreciation Rates	78,000,000
Amount of Increase Related to Amortization of Regulatory Assets	11,000,000
Settled 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
Michigan Base Rate Case - 2017 [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	$ 52,000,000
Requested Return on Common Equity	10.60%
Amount of Increase Related to Annual Depreciation Rates	$ 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%
Alternate Supplier Cap	10.00%
Reduced Capacity Charge Pretax Loss	$ 9,000,000
Approved Annual Revenue Increase	$ 50,000,000
Approved Return On Equity	9.90%
Michigan Base Rate Case - 2017 [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Requested Annual Increase	$ 52,000,000
Requested Return on Common Equity	10.60%
Amount of Increase Related to Annual Depreciation Rates	$ 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%
Alternate Supplier Cap	10.00%
Reduced Capacity Charge Pretax Loss	$ 9,000,000
Approved Annual Revenue Increase	$ 50,000,000
Approved Return On Equity	9.90%
Rockport Plant, Unit 2 Selective Catalytic Reduction [Member]
Public Utilities, General Disclosures [Line Items]
Projected Capital Costs	$ 274,000,000
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
Approved Capital Costs	274,000,000
Kentucky Base Rate Case - 2017 [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
KPSC Order Additional Annual Revenue Increase	765,000
Ohio Electric Security Plan Filing [Member]
Public Utilities, General Disclosures [Line Items]
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 Filed in the Pending Stipulation Agreement	10.00%
Ohio Electric Security Plan Filing [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
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 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
PJM Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Amount of RTEP Refunds Recorded to Customer Accounts Receivable	169,000,000
Amount of RTEP Refunds Recorded to Deferred Charges and Other Noncurrent Assets	$ 82,000,000
FERC Transmission Complaint - AEP PJM Participants [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	$ 50,000,000
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%
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] | 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] | 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