VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) line MW	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2025 GW
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	$ 2,637.6	$ 2,032.5
Securitized Assets	554.3	336.3
Construction work in progress	6,346.9	5,508.0
Investments in Equity Method Investees	1,055.9	1,073.6	$ 1,276.7
Equity Earnings (Loss) of Unconsolidated Subsidiaries	$ 93.7	58.5	(109.4)
Berkshire Hathaway
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Ownership percentage	50.00%
AEPTHCo
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Ownership percentage	50.00%
ETT
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Investments in Equity Method Investees	$ 897.0	811.0
Equity Earnings (Loss) of Unconsolidated Subsidiaries	86.0	74.0	74.0
SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	265.5	198.9
Securitized Assets	331.4	0.0
Construction work in progress	627.3	555.8
Equity Earnings (Loss) of Unconsolidated Subsidiaries	1.4	1.4	1.4
SOUTHWESTERN ELECTRIC POWER COMPANY | Affiliated Entity
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	57.1	45.9
INDIANA MICHIGAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	202.2	225.8
Construction work in progress	334.9	301.7
INDIANA MICHIGAN POWER COMPANY | Billings from AEP Generating Company
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Billings from VIE	209.0	181.0	242.0
INDIANA MICHIGAN POWER COMPANY | Carrying Amount in AEP Generating Company's Accounts Payable
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	14.0	15.0
INDIANA MICHIGAN POWER COMPANY | Affiliated Entity
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	98.5	107.3
AEP TEXAS INC.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	366.2	192.3
Securitized Assets	116.7	202.9
Construction work in progress	1,118.0	904.6
AEP TEXAS INC. | Affiliated Entity
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	34.9	27.7
APPALACHIAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	427.2	280.4
Securitized Assets	106.2	133.4
Construction work in progress	742.6	709.2
APPALACHIAN POWER COMPANY | Affiliated Entity
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	$ 205.9	121.3
Transource Energy
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Equity and voting ownership percentage	86.50%
AEGCo | Rockport Generating Plant
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percent of Ownership	50.00%
Cleco Power, LLC
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percentage of VIE sales of lignite produced	50.00%
OHIO POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	$ 343.6	320.7
Construction work in progress	691.1	654.0
Equity Earnings (Loss) of Unconsolidated Subsidiaries	(1.1)	0.0	0.6
OHIO POWER COMPANY | Affiliated Entity
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	$ 204.9	154.2
Variable Interest Entity, Primary Beneficiary
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Minimum percentage of equity AEP provides	5.00%
Percentage of short term borrowing needs in excess of third party financings	35.00%
Number of lines of insurance for protected cells | line	7
Insurance premium expense to protected cell	$ 37.0	34.0	31.0
Debt-to-total capitalization maximum	67.50%
Variable Interest Entity, Primary Beneficiary | SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Guarantees of mine reclamation amount	$ 155.0
Estimated final cost mine reclamation	100.0
Amount recorded in ARO for final mine closure and reclamation costs	96.0
Amount collected through rider for final Mine closure and reclamation costs	97.0
Amount recorded in other noncurrent assets for final mine closure and reclamation costs	76.0
Securitized Assets	331.0
Variable Interest Entity, Primary Beneficiary | SOUTHWESTERN ELECTRIC POWER COMPANY | Affiliated Entity
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accounts Payable - Affiliated Companies for collected reclamation costs that have been billed to SWEPCo	77.0
Variable Interest Entity, Primary Beneficiary | INDIANA MICHIGAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Capital lease payments made	$ 111.0	97.0	84.0
Capital lease term	54 months
Variable Interest Entity, Primary Beneficiary | AEP TEXAS INC. | AEP Texas Restoration Funding
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitized Assets	$ 117.0	139.0
Variable Interest Entity, Primary Beneficiary | AEP TEXAS INC. | AEP Texas Transition Funding
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitized Assets		64.0
Variable Interest Entity, Primary Beneficiary | APPALACHIAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitized Assets	$ 106.0	133.0
Variable Interest Entity, Primary Beneficiary | Great Plains Energy Inc.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Equity and voting ownership percentage	13.50%
Variable Interest Entity, Primary Beneficiary | Current Liabilities | SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitization Bonds	$ 23.0
Variable Interest Entity, Primary Beneficiary | Current Liabilities | AEP TEXAS INC. | AEP Texas Restoration Funding
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitization Bonds	24.0	24.0
Variable Interest Entity, Primary Beneficiary | Current Liabilities | AEP TEXAS INC. | AEP Texas Transition Funding
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitization Bonds		72.0
Variable Interest Entity, Primary Beneficiary | Current Liabilities | APPALACHIAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitization Bonds	28.0	27.0
Variable Interest Entity, Primary Beneficiary | Noncurrent Liabilities | SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitization Bonds	309.0
Variable Interest Entity, Primary Beneficiary | Noncurrent Liabilities | AEP TEXAS INC. | AEP Texas Restoration Funding
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitization Bonds	102.0	126.0
Variable Interest Entity, Primary Beneficiary | Noncurrent Liabilities | APPALACHIAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Securitization Bonds	$ 91.0	120.0
Variable Interest Entity, Not Primary Beneficiary
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
AEP's ownership In OVEC	43.47%
Approximate OVEC generating capacity (MWs) | MW	2,400
Outstanding Indebtedness	$ 997.0	1,100.0
Variable Interest Entity, Not Primary Beneficiary | Parent
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
AEP's ownership In OVEC	39.17%
Variable Interest Entity, Not Primary Beneficiary | SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Billings from VIE	$ 194.4	185.1	192.5
Percentage of VIE sales of lignite produced	50.00%
Percentage of VIE debt guaranteed	50.00%
Percentage of VIE management fee received	100.00%
Dividends	$ 1.0	1.0	25.0
Variable Interest Entity, Not Primary Beneficiary | INDIANA MICHIGAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Billings from VIE	$ 187.6	178.4	192.4
Power participation ratio	7.85%
Outstanding Indebtedness	$ 78.0	84.0
Variable Interest Entity, Not Primary Beneficiary | AEP TEXAS INC.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Billings from VIE	242.6	228.5	236.8
Variable Interest Entity, Not Primary Beneficiary | APPALACHIAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Billings from VIE	$ 335.3	324.9	347.5
Power participation ratio	15.69%
Outstanding Indebtedness	$ 156.0	168.0
Variable Interest Entity, Not Primary Beneficiary | OHIO POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Billings from VIE	$ 283.4	269.5	$ 272.5
Power acquired, solid oxide fuel cells | MW	100
Construction work in progress	$ 457.0
Borrowings	$ 456.0
AEP's ownership In OVEC	4.30%
Power participation ratio	19.93%
Outstanding Indebtedness	$ 199.0	$ 213.0
Variable Interest Entity, Not Primary Beneficiary | OHIO POWER COMPANY | Forecast [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Power acquired, option, solid oxide fuel cells | GW				1