PROPERTY, PLANT, AND EQUIPMENT - ARO Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	$ 3,031.2	$ 2,943.6
Accretion Expense	140.1	116.3
Liabilities Incurred	612.4	38.9
Liabilities Settled	(102.4)	(130.6)
Revisions in Cash Flow Estimates	(69.6)	63.0
Ending Balance	3,611.7	3,031.2
AEP TEXAS INC.
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	4.5	4.5
Accretion Expense	0.2	0.2
Liabilities Incurred	0.0	0.0
Liabilities Settled	(0.8)	(0.3)
Revisions in Cash Flow Estimates	0.0	0.1
Ending Balance	3.9	4.5
APPALACHIAN POWER COMPANY
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	464.0	427.7
Accretion Expense	27.7	16.8
Liabilities Incurred	247.1	16.1
Liabilities Settled	(18.1)	(23.1)
Revisions in Cash Flow Estimates	81.0	26.5
Ending Balance	801.7	464.0
INDIANA MICHIGAN POWER COMPANY
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	2,106.0	2,028.1
Accretion Expense	80.2	74.8
Liabilities Incurred	85.7	4.8
Liabilities Settled	(2.2)	(3.7)
Revisions in Cash Flow Estimates	(175.9)	2.0
Ending Balance	2,093.8	2,106.0
OHIO POWER COMPANY
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	2.1	5.0
Accretion Expense	1.4	0.2
Liabilities Incurred	52.9	0.0
Liabilities Settled	(0.1)	(3.1)
Revisions in Cash Flow Estimates	0.0	0.0
Ending Balance	56.3	2.1
PUBLIC SERVICE COMPANY OF OKLAHOMA
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	84.2	75.7
Accretion Expense	5.8	4.7
Liabilities Incurred	33.7	5.8
Liabilities Settled	(1.9)	(1.2)
Revisions in Cash Flow Estimates	0.0	(0.8)
Ending Balance	121.8	84.2
SOUTHWESTERN ELECTRIC POWER COMPANY
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	281.6	280.9
Accretion Expense	16.2	13.7
Liabilities Incurred	30.2	7.5
Liabilities Settled	(69.2)	(55.0)
Revisions in Cash Flow Estimates	19.9	34.5
Ending Balance	$ 278.7	$ 281.6