Commitments, Guarantees and Contingencies (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Contractual Commitments
Less than 1 year		$ 975.5
For 2-3 years		1,006.9
For 4-5 years		489.9
After 5 years		1,310.0
Total Contractual Commitments		3,782.3
Commitments, Guarantees and Contingencies (Textuals)
Revolving Credit Facilities		4,000.0
Disposal, Assessed Fees and Related Interest	[1]	281.2	$ 279.8
Asset Retirement Obligation, Period Increase (Decrease)		199.0
AEP Wind Holdings LLC [Member] | Generation and Marketing [Member]
Commitments, Guarantees and Contingencies (Textuals)
Maximum Potential Amount of Future Payments Associated with Guarantee		157.0
Guarantor Obligations, Current Carrying Value		31.0
Guarantor Obligations, Current Carrying Value, Contingent Portion		1.0
Letters of Credit [Member]
Maximum Future Payments for Letters of Credit Under Uncommitted Facilities
Maximum Future Payments for Letters of Credit Issued Under the Uncommitted Facility		179.8
Commitments, Guarantees and Contingencies (Textuals)
Letters of Credit Limit		1,200.0
Uncommitted Facility		405.0
Fuel Purchase Contracts [Member]
Contractual Commitments
Less than 1 year	[2]	763.9
For 2-3 years	[2]	715.1
For 4-5 years	[2]	212.9
After 5 years	[2]	381.5
Total Contractual Commitments	[2]	2,073.4
Energy and Capacity Purchase Contracts [Member]
Contractual Commitments
Less than 1 year		211.6
For 2-3 years		291.8
For 4-5 years		277.0
After 5 years		928.5
Total Contractual Commitments		1,708.9
AEP Texas Inc. [Member] | Letters of Credit [Member]
Maximum Future Payments for Letters of Credit Under Uncommitted Facilities
Maximum Future Payments for Letters of Credit Issued Under the Uncommitted Facility		2.2
Appalachian Power Co [Member]
Contractual Commitments
Less than 1 year		398.3
For 2-3 years		290.1
For 4-5 years		85.5
After 5 years		246.5
Total Contractual Commitments		1,020.4
Commitments, Guarantees and Contingencies (Textuals)
Asset Retirement Obligation, Period Increase (Decrease)		199.0
Appalachian Power Co [Member] | Fuel Purchase Contracts [Member]
Contractual Commitments
Less than 1 year	[2]	362.8
For 2-3 years	[2]	217.6
For 4-5 years	[2]	11.6
After 5 years	[2]	16.3
Total Contractual Commitments	[2]	608.3
Appalachian Power Co [Member] | Energy and Capacity Purchase Contracts [Member]
Contractual Commitments
Less than 1 year		35.5
For 2-3 years		72.5
For 4-5 years		73.9
After 5 years		230.2
Total Contractual Commitments		412.1
Indiana Michigan Power Co [Member]
Contractual Commitments
Less than 1 year		322.9
For 2-3 years		475.6
For 4-5 years		250.2
After 5 years		587.3
Total Contractual Commitments		1,636.0
Commitments, Guarantees and Contingencies (Textuals)
Disposal, Assessed Fees and Related Interest	[1]	281.2	279.8
Indiana Michigan Power Co [Member] | Fuel Purchase Contracts [Member]
Contractual Commitments
Less than 1 year	[2]	157.7
For 2-3 years	[2]	278.9
For 4-5 years	[2]	189.3
After 5 years	[2]	332.7
Total Contractual Commitments	[2]	958.6
Indiana Michigan Power Co [Member] | Energy and Capacity Purchase Contracts [Member]
Contractual Commitments
Less than 1 year		165.2
For 2-3 years		196.7
For 4-5 years		60.9
After 5 years		254.6
Total Contractual Commitments		677.4
Ohio Power Co [Member] | Energy and Capacity Purchase Contracts [Member]
Contractual Commitments
Less than 1 year		28.8
For 2-3 years		58.2
For 4-5 years		58.1
After 5 years		263.3
Total Contractual Commitments		408.4
Public Service Co Of Oklahoma [Member]
Contractual Commitments
Less than 1 year		114.9
For 2-3 years		113.6
For 4-5 years		66.8
After 5 years		160.0
Total Contractual Commitments		455.3
Public Service Co Of Oklahoma [Member] | Fuel Purchase Contracts [Member]
Contractual Commitments
Less than 1 year	[2]	25.3
For 2-3 years	[2]	36.2
For 4-5 years	[2]	0.0
After 5 years	[2]	0.0
Total Contractual Commitments	[2]	61.5
Public Service Co Of Oklahoma [Member] | Energy and Capacity Purchase Contracts [Member]
Contractual Commitments
Less than 1 year		89.6
For 2-3 years		77.4
For 4-5 years		66.8
After 5 years		160.0
Total Contractual Commitments		393.8
Southwestern Electric Power Co [Member]
Contractual Commitments
Less than 1 year		76.8
For 2-3 years		47.6
For 4-5 years		8.4
After 5 years		4.2
Total Contractual Commitments		137.0
Southwestern Electric Power Co [Member] | Fuel Purchase Contracts [Member]
Contractual Commitments
Less than 1 year	[2]	68.5
For 2-3 years	[2]	39.2
For 4-5 years	[2]	0.0
After 5 years	[2]	0.0
Total Contractual Commitments	[2]	107.7
Southwestern Electric Power Co [Member] | Energy and Capacity Purchase Contracts [Member]
Contractual Commitments
Less than 1 year		8.3
For 2-3 years		8.4
For 4-5 years		8.4
After 5 years		4.2
Total Contractual Commitments		29.3
Decommissioning and Low Level Waste Accumulation Disposal [Member]
Commitments, Guarantees and Contingencies (Textuals)
Cost of Decommissioning and Disposal of Radioactive Waste		2,000.0
Additional Ongoing Costs for Post Decommissioning Storage of SNF		6.0
Subsequent Decommissioning of the Spent Fuel Storage Facility		37.0
Amount Recovered in Rates for Decommissioning Costs		4.0	7.0	$ 8.0
Decommissioning Fund Investments, Fair Value		3,000.0	2,700.0
Decommissioning and Low Level Waste Accumulation Disposal [Member] | Indiana Michigan Power Co [Member]
Commitments, Guarantees and Contingencies (Textuals)
Cost of Decommissioning and Disposal of Radioactive Waste		2,000.0
Additional Ongoing Costs for Post Decommissioning Storage of SNF		6.0
Subsequent Decommissioning of the Spent Fuel Storage Facility		37.0
Amount Recovered in Rates for Decommissioning Costs		4.0	7.0	8.0
Decommissioning Fund Investments, Fair Value		3,000.0	2,700.0
Spent Nuclear Fuel Disposal [Member]
Commitments, Guarantees and Contingencies (Textuals)
DOE SNF Disposal Fee		0.0
Disposal, Assessed Fees and Related Interest		281.0	280.0
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition		324.0	323.0
Recovery of Spent Nuclear Fuel Storage Costs		24.0	8.0	11.0
Current Amount Recoverable from the Federal Government		14.0	24.0
Noncurrent Amount Recoverable from the Federal Government		1.0	1.0
Spent Nuclear Fuel Disposal [Member] | Indiana Michigan Power Co [Member]
Commitments, Guarantees and Contingencies (Textuals)
DOE SNF Disposal Fee		0.0
Disposal, Assessed Fees and Related Interest		281.0	280.0
Trust Fund Assets One Time Fee Obligation for Nuclear Fuel Disposition		324.0	323.0
Recovery of Spent Nuclear Fuel Storage Costs		24.0	8.0	$ 11.0
Current Amount Recoverable from the Federal Government		14.0	24.0
Noncurrent Amount Recoverable from the Federal Government		1.0	$ 1.0
Nuclear Incident Liability [Member]
Commitments, Guarantees and Contingencies (Textuals)
Insurance Coverage for Property Damage, Decommissioning and Decontamination		2,700.0
Coverage for Property Damage, Decommissioning and Decontamination for a Nonnuclear Incident		500.0
Contingent Financial Obligation for Mutual Insurance		42.0
Insurance Protection for Public Liability Arising from a Nuclear Incident		13,800.0
Commercially Available Insurance		450.0
Assessed Amount per Nuclear Incident		275.0
Deferred Premium Assessment Annual Payment		41.0
Commercially Available Insurance for Catastrophic Nature		450.0
Liability Coverage Under the Price-Anderson Act		13,300.0
Nuclear Incident Liability [Member] | Indiana Michigan Power Co [Member]
Commitments, Guarantees and Contingencies (Textuals)
Insurance Coverage for Property Damage, Decommissioning and Decontamination		2,700.0
Coverage for Property Damage, Decommissioning and Decontamination for a Nonnuclear Incident		500.0
Contingent Financial Obligation for Mutual Insurance		42.0
Insurance Protection for Public Liability Arising from a Nuclear Incident		13,800.0
Commercially Available Insurance		450.0
Assessed Amount per Nuclear Incident		275.0
Deferred Premium Assessment Annual Payment		41.0
Commercially Available Insurance for Catastrophic Nature		450.0
Liability Coverage Under the Price-Anderson Act		13,300.0
June 2022 [Member] | Letters of Credit [Member]
Commitments, Guarantees and Contingencies (Textuals)
Revolving Credit Facilities		$ 4,000.0

[1] Spent Nuclear Fuel Obligation consists of a liability along with accrued interest for disposal of SNF. See “Spent Nuclear Fuel Disposal” section of Note 6 for additional information.

[2] Represents contractual commitments to purchase coal, natural gas, uranium and other consumables as fuel for electric generation along with related transportation of the fuel.