BENEFIT PLANS - Schedule of Obligation and Funded Status (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Qualified Pension Plan
Change in Fair Value of Plan Assets
Company Contributions	$ 95,000,000	$ 0
Nonqualified Pension Plans
Change in Fair Value of Plan Assets
Company Contributions	8,000,000	14,000,000
Pension Plans
Change in Benefit Obligation
Benefit Obligation as of January 1,	3,872,000,000	4,162,000,000
Service Cost	96,000,000	101,000,000	$ 94,000,000
Interest Cost	211,000,000	207,000,000	219,000,000
Actuarial Loss	46,000,000	(45,000,000)
Settlements		(329,000,000)
Benefit Payments	(382,000,000)	(224,000,000)
Benefit Obligation as of December 31,	3,843,000,000	3,872,000,000	4,162,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	3,666,000,000	4,118,000,000
Actual Gain on Plan Assets	372,000,000	87,000,000
Company Contributions	103,000,000	14,000,000
Settlements		(329,000,000)
Benefit Payments	(382,000,000)	(224,000,000)
Fair Value of Plan Assets as of December 31,	3,759,000,000	3,666,000,000	4,118,000,000
Funded (Underfunded) Status as of December 31,	(84,000,000)	(206,000,000)
Pension Plans | AEP TEXAS INC.
Change in Benefit Obligation
Benefit Obligation as of January 1,	323,000,000	343,000,000
Service Cost	9,000,000	9,000,000	8,000,000
Interest Cost	17,000,000	17,000,000	18,000,000
Actuarial Loss	7,000,000	6,000,000
Settlements		(35,000,000)
Benefit Payments	(29,000,000)	(17,000,000)
Benefit Obligation as of December 31,	327,000,000	323,000,000	343,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	288,000,000	333,000,000
Actual Gain on Plan Assets	32,000,000	7,000,000
Company Contributions	12,000,000	0
Settlements		(35,000,000)
Benefit Payments	(29,000,000)	(17,000,000)
Fair Value of Plan Assets as of December 31,	303,000,000	288,000,000	333,000,000
Funded (Underfunded) Status as of December 31,	(24,000,000)	(35,000,000)
Pension Plans | APPALACHIAN POWER COMPANY
Change in Benefit Obligation
Benefit Obligation as of January 1,	453,000,000	504,000,000
Service Cost	9,000,000	9,000,000	9,000,000
Interest Cost	25,000,000	25,000,000	26,000,000
Actuarial Loss	11,000,000	(13,000,000)
Settlements		(42,000,000)
Benefit Payments	(43,000,000)	(30,000,000)
Benefit Obligation as of December 31,	455,000,000	453,000,000	504,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	488,000,000	550,000,000
Actual Gain on Plan Assets	53,000,000	10,000,000
Company Contributions	0	0
Settlements		(42,000,000)
Benefit Payments	(43,000,000)	(30,000,000)
Fair Value of Plan Assets as of December 31,	498,000,000	488,000,000	550,000,000
Funded (Underfunded) Status as of December 31,	43,000,000	35,000,000
Pension Plans | INDIANA MICHIGAN POWER COMPANY
Change in Benefit Obligation
Benefit Obligation as of January 1,	450,000,000	477,000,000
Service Cost	13,000,000	13,000,000	12,000,000
Interest Cost	25,000,000	24,000,000	25,000,000
Actuarial Loss	5,000,000	(8,000,000)
Settlements		(33,000,000)
Benefit Payments	(45,000,000)	(23,000,000)
Benefit Obligation as of December 31,	448,000,000	450,000,000	477,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	507,000,000	551,000,000
Actual Gain on Plan Assets	50,000,000	12,000,000
Company Contributions	2,000,000	0
Settlements		(33,000,000)
Benefit Payments	(45,000,000)	(23,000,000)
Fair Value of Plan Assets as of December 31,	514,000,000	507,000,000	551,000,000
Funded (Underfunded) Status as of December 31,	66,000,000	57,000,000
Pension Plans | OHIO POWER COMPANY
Change in Benefit Obligation
Benefit Obligation as of January 1,	351,000,000	378,000,000
Service Cost	9,000,000	9,000,000	8,000,000
Interest Cost	19,000,000	19,000,000	20,000,000
Actuarial Loss	6,000,000	(8,000,000)
Settlements		(23,000,000)
Benefit Payments	(39,000,000)	(24,000,000)
Benefit Obligation as of December 31,	346,000,000	351,000,000	378,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	381,000,000	419,000,000
Actual Gain on Plan Assets	39,000,000	9,000,000
Company Contributions	0	0
Settlements		(23,000,000)
Benefit Payments	(39,000,000)	(24,000,000)
Fair Value of Plan Assets as of December 31,	381,000,000	381,000,000	419,000,000
Funded (Underfunded) Status as of December 31,	35,000,000	30,000,000
Pension Plans | PUBLIC SERVICE COMPANY OF OKLAHOMA
Change in Benefit Obligation
Benefit Obligation as of January 1,	190,000,000	202,000,000
Service Cost	6,000,000	6,000,000	5,000,000
Interest Cost	10,000,000	10,000,000	11,000,000
Actuarial Loss	2,000,000	0
Settlements		(18,000,000)
Benefit Payments	(18,000,000)	(10,000,000)
Benefit Obligation as of December 31,	190,000,000	190,000,000	202,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	200,000,000	223,000,000
Actual Gain on Plan Assets	21,000,000	5,000,000
Company Contributions	2,000,000	0
Settlements		(18,000,000)
Benefit Payments	(18,000,000)	(10,000,000)
Fair Value of Plan Assets as of December 31,	205,000,000	200,000,000	223,000,000
Funded (Underfunded) Status as of December 31,	15,000,000	10,000,000
Pension Plans | SOUTHWESTERN ELECTRIC POWER COMPANY
Change in Benefit Obligation
Benefit Obligation as of January 1,	228,000,000	261,000,000
Service Cost	8,000,000	8,000,000	8,000,000
Interest Cost	13,000,000	12,000,000	14,000,000
Actuarial Loss	4,000,000	(11,000,000)
Settlements		(33,000,000)
Benefit Payments	(20,000,000)	(9,000,000)
Benefit Obligation as of December 31,	233,000,000	228,000,000	261,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	189,000,000	227,000,000
Actual Gain on Plan Assets	22,000,000	4,000,000
Company Contributions	9,000,000	0
Settlements		(33,000,000)
Benefit Payments	(20,000,000)	(9,000,000)
Fair Value of Plan Assets as of December 31,	200,000,000	189,000,000	227,000,000
Funded (Underfunded) Status as of December 31,	(33,000,000)	(39,000,000)
OPEB
Change in Benefit Obligation
Benefit Obligation as of January 1,	647,000,000	850,000,000
Service Cost	4,000,000	4,000,000	5,000,000
Interest Cost	34,000,000	42,000,000	46,000,000
Actuarial Loss	(50,000,000)	(192,000,000)
Special/Contractual Termination Benefits		4,000,000
Benefit Payments	(105,000,000)	(106,000,000)
Participant Contributions	46,000,000	45,000,000
Benefit Obligation as of December 31,	576,000,000	647,000,000	850,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	1,776,000,000	1,673,000,000
Actual Gain on Plan Assets	262,000,000	160,000,000
Company Contributions	1,000,000	4,000,000
Participant Contributions	46,000,000	45,000,000
Benefit Payments	(105,000,000)	(106,000,000)
Fair Value of Plan Assets as of December 31,	1,980,000,000	1,776,000,000	1,673,000,000
Funded (Underfunded) Status as of December 31,	1,404,000,000	1,129,000,000
OPEB | AEP TEXAS INC.
Change in Benefit Obligation
Benefit Obligation as of January 1,	50,000,000	66,000,000
Service Cost	0	0	0
Interest Cost	3,000,000	3,000,000	4,000,000
Actuarial Loss	(1,000,000)	(15,000,000)
Special/Contractual Termination Benefits		0
Benefit Payments	(9,000,000)	(8,000,000)
Participant Contributions	3,000,000	4,000,000
Benefit Obligation as of December 31,	46,000,000	50,000,000	66,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	147,000,000	137,000,000
Actual Gain on Plan Assets	27,000,000	14,000,000
Company Contributions	0	0
Participant Contributions	3,000,000	4,000,000
Benefit Payments	(9,000,000)	(8,000,000)
Fair Value of Plan Assets as of December 31,	168,000,000	147,000,000	137,000,000
Funded (Underfunded) Status as of December 31,	122,000,000	97,000,000
OPEB | APPALACHIAN POWER COMPANY
Change in Benefit Obligation
Benefit Obligation as of January 1,	102,000,000	135,000,000
Service Cost	1,000,000	0	1,000,000
Interest Cost	5,000,000	7,000,000	7,000,000
Actuarial Loss	(8,000,000)	(31,000,000)
Special/Contractual Termination Benefits		1,000,000
Benefit Payments	(17,000,000)	(17,000,000)
Participant Contributions	7,000,000	7,000,000
Benefit Obligation as of December 31,	90,000,000	102,000,000	135,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	256,000,000	243,000,000
Actual Gain on Plan Assets	39,000,000	22,000,000
Company Contributions	1,000,000	1,000,000
Participant Contributions	7,000,000	7,000,000
Benefit Payments	(17,000,000)	(17,000,000)
Fair Value of Plan Assets as of December 31,	286,000,000	256,000,000	243,000,000
Funded (Underfunded) Status as of December 31,	196,000,000	154,000,000
OPEB | INDIANA MICHIGAN POWER COMPANY
Change in Benefit Obligation
Benefit Obligation as of January 1,	73,000,000	99,000,000
Service Cost	0	1,000,000	1,000,000
Interest Cost	4,000,000	5,000,000	5,000,000
Actuarial Loss	(5,000,000)	(25,000,000)
Special/Contractual Termination Benefits		0
Benefit Payments	(13,000,000)	(13,000,000)
Participant Contributions	6,000,000	6,000,000
Benefit Obligation as of December 31,	65,000,000	73,000,000	99,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	212,000,000	205,000,000
Actual Gain on Plan Assets	32,000,000	14,000,000
Company Contributions	0	0
Participant Contributions	6,000,000	6,000,000
Benefit Payments	(13,000,000)	(13,000,000)
Fair Value of Plan Assets as of December 31,	237,000,000	212,000,000	205,000,000
Funded (Underfunded) Status as of December 31,	172,000,000	139,000,000
OPEB | OHIO POWER COMPANY
Change in Benefit Obligation
Benefit Obligation as of January 1,	63,000,000	86,000,000
Service Cost	0	0	0
Interest Cost	3,000,000	4,000,000	4,000,000
Actuarial Loss	(4,000,000)	(21,000,000)
Special/Contractual Termination Benefits		0
Benefit Payments	(11,000,000)	(11,000,000)
Participant Contributions	5,000,000	5,000,000
Benefit Obligation as of December 31,	56,000,000	63,000,000	86,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	185,000,000	177,000,000
Actual Gain on Plan Assets	24,000,000	14,000,000
Company Contributions	0	0
Participant Contributions	5,000,000	5,000,000
Benefit Payments	(11,000,000)	(11,000,000)
Fair Value of Plan Assets as of December 31,	203,000,000	185,000,000	177,000,000
Funded (Underfunded) Status as of December 31,	147,000,000	122,000,000
OPEB | PUBLIC SERVICE COMPANY OF OKLAHOMA
Change in Benefit Obligation
Benefit Obligation as of January 1,	33,000,000	44,000,000
Service Cost	0	0	0
Interest Cost	2,000,000	2,000,000	2,000,000
Actuarial Loss	(2,000,000)	(10,000,000)
Special/Contractual Termination Benefits		0
Benefit Payments	(6,000,000)	(6,000,000)
Participant Contributions	3,000,000	3,000,000
Benefit Obligation as of December 31,	30,000,000	33,000,000	44,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	95,000,000	90,000,000
Actual Gain on Plan Assets	17,000,000	8,000,000
Company Contributions	0	0
Participant Contributions	3,000,000	3,000,000
Benefit Payments	(6,000,000)	(6,000,000)
Fair Value of Plan Assets as of December 31,	109,000,000	95,000,000	90,000,000
Funded (Underfunded) Status as of December 31,	79,000,000	62,000,000
OPEB | SOUTHWESTERN ELECTRIC POWER COMPANY
Change in Benefit Obligation
Benefit Obligation as of January 1,	41,000,000	54,000,000
Service Cost	0	0	0
Interest Cost	2,000,000	3,000,000	3,000,000
Actuarial Loss	(2,000,000)	(12,000,000)
Special/Contractual Termination Benefits		0
Benefit Payments	(7,000,000)	(7,000,000)
Participant Contributions	3,000,000	3,000,000
Benefit Obligation as of December 31,	37,000,000	41,000,000	54,000,000
Change in Fair Value of Plan Assets
Fair Value of Plan Assets as of January 1,	121,000,000	111,000,000
Actual Gain on Plan Assets	21,000,000	14,000,000
Company Contributions	0	0
Participant Contributions	3,000,000	3,000,000
Benefit Payments	(7,000,000)	(7,000,000)
Fair Value of Plan Assets as of December 31,	138,000,000	121,000,000	$ 111,000,000
Funded (Underfunded) Status as of December 31,	$ 101,000,000	$ 80,000,000