COMMITMENTS, GUARANTEES AND CONTINGENCIES - Narrative (Details)	1 Months Ended		12 Months Ended
	Nov. 30, 2025 a	May 31, 2014 USD ($)	Dec. 31, 2025 USD ($) a site uncommittedFacility millsPerKWh unit MW	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jan. 31, 2026 USD ($)
Other Commitments [Line Items]
Number of uncommitted facilities | uncommittedFacility			6
Area of land closed, noncompliant with CCR rule | a			300
Cook Plant
Other Commitments [Line Items]
Nuclear contingencies, producing power | MW			2,296
INDIANA MICHIGAN POWER COMPANY | Cook Plant
Other Commitments [Line Items]
Nuclear contingencies, number of units | unit			2
Environmental Response Compensation and Liability Act (Superfund) and State Remediation
Other Commitments [Line Items]
Number of additional sites for which could lead to potentially responsible party designation | site			11
Environmental Response Compensation and Liability Act (Superfund) and State Remediation | AEP Generation Resources Inc.
Other Commitments [Line Items]
Number of sites for which potentially responsible party designation was named | site			1
Environmental Response Compensation and Liability Act (Superfund) and State Remediation | APPALACHIAN POWER COMPANY
Other Commitments [Line Items]
Number of sites for which potentially responsible party designation was named | site			1
Environmental Response Compensation and Liability Act (Superfund) and State Remediation | OHIO POWER COMPANY
Other Commitments [Line Items]
Number of sites for which potentially responsible party designation was named | site			2
Environmental Response Compensation and Liability Act (Superfund) and State Remediation | SOUTHWESTERN ELECTRIC POWER COMPANY
Other Commitments [Line Items]
Number of sites for which potentially responsible party designation was named | site			1
Decommissioning and Low Level Waste Accumulation Disposal
Other Commitments [Line Items]
Cost of decommissioning and disposal of radioactive waste			$ 2,400,000,000
Additional ongoing costs for post decommissioning storage of SNF			7,000,000
Subsequent decommissioning of the spent fuel storage facility			45,000,000
Decommissioning trust assets amount			4,500,000,000	$ 4,000,000,000
Decommissioning and Low Level Waste Accumulation Disposal | INDIANA MICHIGAN POWER COMPANY
Other Commitments [Line Items]
Cost of decommissioning and disposal of radioactive waste			2,400,000,000
Additional ongoing costs for post decommissioning storage of SNF			7,000,000
Subsequent decommissioning of the spent fuel storage facility			45,000,000
Decommissioning trust assets amount			4,500,000,000	4,000,000,000
Spent Nuclear Fuel Disposal
Other Commitments [Line Items]
DOE SNF disposal fee		$ 0
Disposal, assessed fees and related interest			330,000,000	316,000,000
Trust fund assets one time fee obligation for nuclear fuel disposition			381,000,000	367,000,000
Spent nuclear fuel storage costs recovery			11,000,000	12,000,000	$ 21,000,000
Settlement amount recoverable for dry cask current			25,000,000	11,000,000
Settlement amount recoverable for dry cask noncurrent			$ 1,000,000	15,000,000
Spent Nuclear Fuel Disposal | INDIANA MICHIGAN POWER COMPANY
Other Commitments [Line Items]
Spent nuclear fuel obligation, fee charged | millsPerKWh			1,000,000
DOE SNF disposal fee		$ 0
Disposal, assessed fees and related interest			$ 330,000,000	316,000,000
Trust fund assets one time fee obligation for nuclear fuel disposition			381,000,000	367,000,000
Spent nuclear fuel storage costs recovery			11,000,000	12,000,000	$ 21,000,000
Settlement amount recoverable for dry cask current			25,000,000	11,000,000
Settlement amount recoverable for dry cask noncurrent			1,000,000	$ 15,000,000
Nuclear Incident Liability
Other Commitments [Line Items]
Insurance coverage for property damage decommissioning and decontamination			2,700,000,000
Nonnuclear incident coverage for property damage decommissioning and decontamination			1,000,000,000
Contingent financial obligation for mutual insurance			49,000,000
Insurance protection for public liability arising from nuclear incident			16,300,000,000
Commercially available insurance			500,000,000
Assessed amount per nuclear incident			332,000,000
Deferred premium assessment annual payment			49,000,000
Commercially available insurance for catastrophic nature			500,000,000
Liability coverage under Price Anderson Act			15,800,000,000
Nuclear Incident Liability | INDIANA MICHIGAN POWER COMPANY
Other Commitments [Line Items]
Insurance coverage for property damage decommissioning and decontamination			2,700,000,000
Nonnuclear incident coverage for property damage decommissioning and decontamination			1,000,000,000
Contingent financial obligation for mutual insurance			49,000,000
Insurance protection for public liability arising from nuclear incident			16,300,000,000
Commercially available insurance			500,000,000
Assessed amount per nuclear incident			332,000,000
Deferred premium assessment annual payment			49,000,000
Commercially available insurance for catastrophic nature			500,000,000
Liability coverage under Price Anderson Act			15,800,000,000
CCR Rule Revision
Other Commitments [Line Items]
Extended compliance deadline applicable period	3 years
Closure deadlines for unlined surface impoundments, minimum (in acres) | a	40
CCR Rule Revision | APPALACHIAN POWER COMPANY | Subsequent Event
Other Commitments [Line Items]
Asset retirement obligation, approved recovery amount						$ 80,000,000
Letter of Credit
Other Commitments [Line Items]
Debt instrument, face amount			450,000,000
Revolving Credit Facility | Letter of Credit
Other Commitments [Line Items]
Letters of credit outstanding, amount			0
Revolving Credit Facility | Letter of Credit | Subsidiaries
Other Commitments [Line Items]
Line of credit facility, borrowing capacity			1,200,000,000
Revolving Credit Facility | Revolving Credit Facility, Due March 2029 | Line of Credit
Other Commitments [Line Items]
Line of credit facility, borrowing capacity			5,000,000,000
Revolving Credit Facility | Revolving Credit Facility, Due March 2027 | Line of Credit
Other Commitments [Line Items]
Line of credit facility, borrowing capacity			$ 1,000,000,000