VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - Investments (Details) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outstanding Indebtedness	$ 997.0	$ 1,100.0
APPALACHIAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outstanding Indebtedness	156.0	168.0
INDIANA MICHIGAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outstanding Indebtedness	78.0	84.0
OHIO POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outstanding Indebtedness	199.0	213.0
Billings from AEP Service Corporation | AEP TEXAS INC.
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	26.1	15.1
Maximum Exposure	26.1	15.1
Billings from AEP Service Corporation | AEP TRANSMISSION COMPANY, LLC
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	29.3	17.9
Maximum Exposure	29.3	17.9
Billings from AEP Service Corporation | APPALACHIAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	36.4	21.1
Maximum Exposure	36.4	21.1
Billings from AEP Service Corporation | INDIANA MICHIGAN POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	25.1	14.3
Maximum Exposure	25.1	14.3
Billings from AEP Service Corporation | OHIO POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	34.5	19.0
Maximum Exposure	34.5	19.0
Billings from AEP Service Corporation | PUBLIC SERVICE COMPANY OF OKLAHOMA
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	19.2	10.6
Maximum Exposure	19.2	10.6
Billings from AEP Service Corporation | SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	22.0	12.7
Maximum Exposure	22.0	12.7
Capital Contribution From Parent
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	4.4	4.4
Maximum Exposure	4.4	4.4
Capital Contribution From Parent | SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	7.6	7.6
Maximum Exposure	7.6	7.6
Retained Earnings | SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	0.3	0.4
Maximum Exposure	0.3	0.4
SWEPCo's Share of Obligations | SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	0.0	0.0
Maximum Exposure	15.6	19.2
Total Investment
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	4.4	4.4
Maximum Exposure	437.6	469.7
Total Investment | SOUTHWESTERN ELECTRIC POWER COMPANY
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	7.9	8.0
Maximum Exposure	23.5	27.2
AEP's Ratio of OVEC Debt
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
As Reported on the Balance Sheet	0.0	0.0
Maximum Exposure	$ 433.2	$ 465.3