PROPERTY, PLANT AND EQUIPMENT - ARO Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	$ 3,612	$ 3,031
Accretion Expense	170	140
Liabilities Incurred	45	612
Liabilities Settled	(103)	(102)
Revisions in Cash Flow Estimates	(12)	(69)
Ending Balance	3,712	3,612
AEP TEXAS INC.
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	4	5
Accretion Expense	0	0
Liabilities Incurred	0	0
Liabilities Settled	0	(1)
Revisions in Cash Flow Estimates	0	0
Ending Balance	4	4
APPALACHIAN POWER COMPANY
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	802	464
Accretion Expense	42	28
Liabilities Incurred	4	247
Liabilities Settled	(19)	(18)
Revisions in Cash Flow Estimates	(51)	81
Ending Balance	778	802
INDIANA MICHIGAN POWER COMPANY
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	2,094	2,106
Accretion Expense	86	80
Liabilities Incurred	0	86
Liabilities Settled	(2)	(2)
Revisions in Cash Flow Estimates	4	(176)
Ending Balance	2,182	2,094
OHIO POWER COMPANY
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	56	2
Accretion Expense	4	1
Liabilities Incurred	0	53
Liabilities Settled	(1)	0
Revisions in Cash Flow Estimates	1	0
Ending Balance	60	56
PUBLIC SERVICE COMPANY OF OKLAHOMA
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	122	84
Accretion Expense	8	6
Liabilities Incurred	19	34
Liabilities Settled	(3)	(2)
Revisions in Cash Flow Estimates	(3)	0
Ending Balance	143	122
SOUTHWESTERN ELECTRIC POWER COMPANY
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	279	282
Accretion Expense	16	16
Liabilities Incurred	20	30
Liabilities Settled	(65)	(69)
Revisions in Cash Flow Estimates	40	20
Ending Balance	$ 290	$ 279