Commitments, Guarantees and Contingencies (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Maximum Potential Loss [Abstract]
Max Potential Loss on Master Lease Agreements	$ 47.8
Commitments, Guarantees and Contingencies (Textuals) [Abstract]
Rockport Plant, Unit 2 Acquisition Price	115.5
AEP Wind Holdings LLC [Member] | Generation And Marketing [Member]
Commitments, Guarantees and Contingencies (Textuals) [Abstract]
Maximum Potential Amount of Future Payments Associated with Guarantee	148.0
Guarantor Obligations, Current Carrying Value	29.0
Guarantor Obligations, Current Carrying Value, Contingent Portion	2.0
AEP Texas Inc. [Member]
Maximum Potential Loss [Abstract]
Max Potential Loss on Master Lease Agreements	11.1
Appalachian Power Co [Member]
Maximum Potential Loss [Abstract]
Max Potential Loss on Master Lease Agreements	6.2
Indiana Michigan Power Co [Member]
Maximum Potential Loss [Abstract]
Max Potential Loss on Master Lease Agreements	4.1
Commitments, Guarantees and Contingencies (Textuals) [Abstract]
Rockport Plant, Unit 2 Acquisition Price	115.5
Ohio Power Co [Member]
Maximum Potential Loss [Abstract]
Max Potential Loss on Master Lease Agreements	7.6
Public Service Co Of Oklahoma [Member]
Maximum Potential Loss [Abstract]
Max Potential Loss on Master Lease Agreements	4.7
Southwestern Electric Power Co [Member]
Maximum Potential Loss [Abstract]
Max Potential Loss on Master Lease Agreements	5.2
Rockport Lease [Member]
Present Value of Future Minimum Lease Payments, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
Minimum Lease Payments, Sale Leaseback Transactions, Next Twelve Months	74.0	[1]
Minimum Lease Payments, Sale Leaseback Transactions, within Two Years	147.6	[1]
Minimum Lease Payments, Sale Leaseback Transactions	221.6	[1]
Rockport Lease [Member] | Indiana Michigan Power Co [Member]
Present Value of Future Minimum Lease Payments, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
Minimum Lease Payments, Sale Leaseback Transactions, Next Twelve Months	37.0
Minimum Lease Payments, Sale Leaseback Transactions, within Two Years	73.8
Minimum Lease Payments, Sale Leaseback Transactions	110.8
Boat and Barge Leases [Member]
Commitments, Guarantees and Contingencies (Textuals) [Abstract]
Guarantor Obligations, Current Carrying Value	2.0
Maximum Potential Lease Payments, AEPRO Barge and Boat Leases	43.0
Guarantee Obligations Current Carrying Value Other Liabilities Current	1.0
Guarantee Obligations Current Carrying Value Other Liabilities Noncurrent	1.0
Letters of Credit [Member]
Maximum Future Payments for Letters of Credit [Abstract]
Maximum Future Payments for Letters of Credit Issued Under the Uncommitted Facility	179.5
Commitments, Guarantees and Contingencies (Textuals) [Abstract]
Letters of Credit Limit	1,200.0
Uncommitted Facility	375.0
Letters of Credit [Member] | AEP Texas Inc. [Member]
Maximum Future Payments for Letters of Credit [Abstract]
Maximum Future Payments for Letters of Credit Issued Under the Uncommitted Facility	2.2
March 2026 | Letters of Credit [Member]
Commitments, Guarantees and Contingencies (Textuals) [Abstract]
Revolving Credit Facilities	4,000.0
March 2023 | Letters of Credit [Member]
Commitments, Guarantees and Contingencies (Textuals) [Abstract]
Revolving Credit Facilities	$ 1,000.0

[1] AEP’s future minimum lease payments include equal shares from AEGCo and I&M.