BENEFIT PLANS - Schedule of Amounts Included in Regulatory Assets, Deferred Income Taxes and AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	$ 1,094	$ 1,154
Actuarial Gain (Loss) During the Year	(44)	188
Amortization of Actuarial Loss	(16)	(5)
Amounts Recognized Due to Settlement		(93)
Change for the Year	(60)	90
Pension Plans | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	984	1,020
Pension Plans | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	23	28
Pension Plans | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	87	106
Pension Plans | AEP TEXAS INC.
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	185	189
Actuarial Gain (Loss) During the Year	(3)	24
Amortization of Actuarial Loss	(1)	0
Amounts Recognized Due to Settlement		(10)
Change for the Year	(4)	14
Pension Plans | AEP TEXAS INC. | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	173	177
Pension Plans | AEP TEXAS INC. | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	2	2
Pension Plans | AEP TEXAS INC. | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	10	10
Pension Plans | APPALACHIAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	105	112
Actuarial Gain (Loss) During the Year	(5)	19
Amortization of Actuarial Loss	(2)	0
Amounts Recognized Due to Settlement		(12)
Change for the Year	(7)	7
Pension Plans | APPALACHIAN POWER COMPANY | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	104	110
Pension Plans | APPALACHIAN POWER COMPANY | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
Pension Plans | APPALACHIAN POWER COMPANY | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	1	2
Pension Plans | INDIANA MICHIGAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	0	8
Actuarial Gain (Loss) During the Year	(6)	23
Amortization of Actuarial Loss	(2)	(1)
Amounts Recognized Due to Settlement		(9)
Change for the Year	(8)	13
Pension Plans | INDIANA MICHIGAN POWER COMPANY | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	9	18
Pension Plans | INDIANA MICHIGAN POWER COMPANY | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(1)	(2)
Pension Plans | INDIANA MICHIGAN POWER COMPANY | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(8)	(8)
Pension Plans | OHIO POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	135	141
Actuarial Gain (Loss) During the Year	(5)	16
Amortization of Actuarial Loss	(1)	0
Amounts Recognized Due to Settlement		(7)
Change for the Year	(6)	9
Pension Plans | OHIO POWER COMPANY | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	135	141
Pension Plans | OHIO POWER COMPANY | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
Pension Plans | OHIO POWER COMPANY | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
Pension Plans | PUBLIC SERVICE COMPANY OF OKLAHOMA
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	49	54
Actuarial Gain (Loss) During the Year	(4)	12
Amortization of Actuarial Loss	(1)	0
Amounts Recognized Due to Settlement		(5)
Change for the Year	(5)	7
Pension Plans | PUBLIC SERVICE COMPANY OF OKLAHOMA | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	49	54
Pension Plans | PUBLIC SERVICE COMPANY OF OKLAHOMA | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
Pension Plans | PUBLIC SERVICE COMPANY OF OKLAHOMA | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
Pension Plans | SOUTHWESTERN ELECTRIC POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	79	83
Actuarial Gain (Loss) During the Year	(3)	2
Amortization of Actuarial Loss	(1)	0
Amounts Recognized Due to Settlement		(9)
Change for the Year	(4)	(7)
Pension Plans | SOUTHWESTERN ELECTRIC POWER COMPANY | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	79	83
Pension Plans | SOUTHWESTERN ELECTRIC POWER COMPANY | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
Pension Plans | SOUTHWESTERN ELECTRIC POWER COMPANY | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
OPEB
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	(241)	(42)
Prior Service Cost	(12)	(15)
Actuarial Gain (Loss) During the Year	(199)	(240)
Amortization of Actuarial Loss		(3)
Amortization of Prior Service Credit	3	13
Change for the Year	(196)	(230)
OPEB | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(195)	(56)
OPEB | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(12)	0
OPEB | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(46)	(1)
OPEB | AEP TEXAS INC.
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	(18)	2
Prior Service Cost	(1)	(1)
Actuarial Gain (Loss) During the Year	(20)	(20)
Amortization of Actuarial Loss		0
Amortization of Prior Service Credit	0	1
Change for the Year	(20)	(19)
OPEB | AEP TEXAS INC. | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(18)	1
OPEB | AEP TEXAS INC. | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
OPEB | AEP TEXAS INC. | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(1)	0
OPEB | APPALACHIAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	(40)	(10)
Prior Service Cost	(2)	(2)
Actuarial Gain (Loss) During the Year	(30)	(37)
Amortization of Actuarial Loss		0
Amortization of Prior Service Credit	0	2
Change for the Year	(30)	(35)
OPEB | APPALACHIAN POWER COMPANY | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(15)	(2)
OPEB | APPALACHIAN POWER COMPANY | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(6)	(2)
OPEB | APPALACHIAN POWER COMPANY | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(21)	(8)
OPEB | INDIANA MICHIGAN POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	(21)	2
Prior Service Cost	(3)	(2)
Actuarial Gain (Loss) During the Year	(23)	(26)
Amortization of Actuarial Loss		(1)
Amortization of Prior Service Credit	(1)	2
Change for the Year	(24)	(25)
OPEB | INDIANA MICHIGAN POWER COMPANY | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(24)	(3)
OPEB | INDIANA MICHIGAN POWER COMPANY | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	1
OPEB | INDIANA MICHIGAN POWER COMPANY | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	2
OPEB | OHIO POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	(23)	(5)
Prior Service Cost	(1)	(2)
Actuarial Gain (Loss) During the Year	(18)	(23)
Amortization of Actuarial Loss		0
Amortization of Prior Service Credit	1	1
Change for the Year	(17)	(22)
OPEB | OHIO POWER COMPANY | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(24)	(7)
OPEB | OHIO POWER COMPANY | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
OPEB | OHIO POWER COMPANY | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
OPEB | PUBLIC SERVICE COMPANY OF OKLAHOMA
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	(7)	5
Prior Service Cost	(1)	(1)
Actuarial Gain (Loss) During the Year	(12)	(13)
Amortization of Actuarial Loss		0
Amortization of Prior Service Credit	0	1
Change for the Year	(12)	(12)
OPEB | PUBLIC SERVICE COMPANY OF OKLAHOMA | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(8)	4
OPEB | PUBLIC SERVICE COMPANY OF OKLAHOMA | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
OPEB | PUBLIC SERVICE COMPANY OF OKLAHOMA | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	0	0
OPEB | SOUTHWESTERN ELECTRIC POWER COMPANY
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial Gain	(15)	0
Prior Service Cost	(1)	(1)
Actuarial Gain (Loss) During the Year	(15)	(18)
Amortization of Actuarial Loss		0
Amortization of Prior Service Credit	0	1
Change for the Year	(15)	(17)
OPEB | SOUTHWESTERN ELECTRIC POWER COMPANY | Regulatory Assets
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(9)	0
OPEB | SOUTHWESTERN ELECTRIC POWER COMPANY | Deferred Income Taxes
Defined Benefit Plan Disclosure [Line Items]
Recorded as	(1)	0
OPEB | SOUTHWESTERN ELECTRIC POWER COMPANY | Net of Tax AOCI
Defined Benefit Plan Disclosure [Line Items]
Recorded as	$ (6)	$ (1)