VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - Schedule of Consolidated Assets And Liabilities of Variable Interest Entities (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
ASSETS
Current Assets	$ 6,623	$ 6,052
Net Property, Plant and Equipment	94,854	92,374
Other Noncurrent Assets	16,299	16,034
TOTAL ASSETS	117,776	114,460
LIABILITIES AND EQUITY
Current Liabilities	12,594	13,314
Noncurrent Liabilities	72,153	68,890
Equity	32,978	32,218	$ 27,364	$ 26,986
TOTAL LIABILITIES AND EQUITY	117,776	114,460
SOUTHWESTERN ELECTRIC POWER COMPANY
ASSETS
Current Assets	655	556
Net Property, Plant and Equipment	11,550	11,341
Other Noncurrent Assets	1,735	1,627
TOTAL ASSETS	13,940	13,524
LIABILITIES AND EQUITY
Current Liabilities	1,740	1,885
Noncurrent Liabilities	7,117	6,740
Equity	5,083	4,899	$ 3,953	$ 3,905
TOTAL LIABILITIES AND EQUITY	13,940	13,524
INDIANA MICHIGAN POWER COMPANY
ASSETS
Current Assets	730	784
Net Property, Plant and Equipment	8,915	7,944
Other Noncurrent Assets	5,760	5,897
TOTAL ASSETS	15,405	14,625
LIABILITIES AND EQUITY
Current Liabilities	1,012	949
Noncurrent Liabilities	10,461	9,892
TOTAL LIABILITIES AND EQUITY	15,405	14,625
AEP TEXAS INC.
ASSETS
Current Assets	719	509
Net Property, Plant and Equipment	16,328	15,864
Other Noncurrent Assets	826	702
TOTAL ASSETS	17,873	17,075
LIABILITIES AND EQUITY
Current Liabilities	1,315	1,418
Noncurrent Liabilities	10,612	9,831
TOTAL LIABILITIES AND EQUITY	17,873	17,075
APPALACHIAN POWER COMPANY
ASSETS
Current Assets	1,215	1,033
Net Property, Plant and Equipment	14,805	14,713
Other Noncurrent Assets	2,121	2,046
TOTAL ASSETS	18,141	17,792
LIABILITIES AND EQUITY
Current Liabilities	2,411	2,384
Noncurrent Liabilities	9,274	9,228
TOTAL LIABILITIES AND EQUITY	18,141	17,792
Variable Interest Entity, Primary Beneficiary | AEP Credit
ASSETS
Current Assets	1,247	1,232
Net Property, Plant and Equipment	0	0
Other Noncurrent Assets	11	10
TOTAL ASSETS	1,258	1,242
LIABILITIES AND EQUITY
Current Liabilities	1,182	1,176
Noncurrent Liabilities	0	1
Equity	76	65
TOTAL LIABILITIES AND EQUITY	1,258	1,242
Variable Interest Entity, Primary Beneficiary | Protected Cell of EIS
ASSETS
Current Assets	236	223
Net Property, Plant and Equipment	0	0
Other Noncurrent Assets	0	0
TOTAL ASSETS	236	223
LIABILITIES AND EQUITY
Current Liabilities	77	56
Noncurrent Liabilities	108	102
Equity	51	65
TOTAL LIABILITIES AND EQUITY	236	223
Variable Interest Entity, Primary Beneficiary | Transource Energy
ASSETS
Current Assets	37	45
Net Property, Plant and Equipment	672	658
Other Noncurrent Assets	9	4
TOTAL ASSETS	718	707
LIABILITIES AND EQUITY
Current Liabilities	33	50
Noncurrent Liabilities	316	298
Equity	369	359
TOTAL LIABILITIES AND EQUITY	718	707
Variable Interest Entity, Primary Beneficiary | SOUTHWESTERN ELECTRIC POWER COMPANY | Sabine
ASSETS
Current Assets	5	1
Net Property, Plant and Equipment	0	0
Other Noncurrent Assets	74	80
TOTAL ASSETS	79	81
LIABILITIES AND EQUITY
Current Liabilities	14	15
Noncurrent Liabilities	65	66
Equity	0	0
TOTAL LIABILITIES AND EQUITY	79	81
Variable Interest Entity, Primary Beneficiary | SOUTHWESTERN ELECTRIC POWER COMPANY | SWEPCo Storm Recovery Funding
ASSETS
Current Assets	10	17
Net Property, Plant and Equipment	0	0
Other Noncurrent Assets	311	312
TOTAL ASSETS	321	329
LIABILITIES AND EQUITY
Current Liabilities	19	23
Noncurrent Liabilities	300	304
Equity	2	2
TOTAL LIABILITIES AND EQUITY	321	329
Variable Interest Entity, Primary Beneficiary | INDIANA MICHIGAN POWER COMPANY | DCC Fuel
ASSETS
Current Assets	108	118
Net Property, Plant and Equipment	195	227
Other Noncurrent Assets	97	118
TOTAL ASSETS	400	463
LIABILITIES AND EQUITY
Current Liabilities	108	118
Noncurrent Liabilities	292	345
Equity	0	0
TOTAL LIABILITIES AND EQUITY	400	463
Variable Interest Entity, Primary Beneficiary | AEP TEXAS INC. | AEP Texas Restoration Funding | Intersegment Eliminations
ASSETS
Other Noncurrent Assets	(4)	(4)
Variable Interest Entity, Primary Beneficiary | AEP TEXAS INC. | AEP Texas Restoration Funding
ASSETS
Current Assets	10	18
Net Property, Plant and Equipment	0	0
Other Noncurrent Assets	93	98
TOTAL ASSETS	103	116
LIABILITIES AND EQUITY
Current Liabilities	31	31
Noncurrent Liabilities	71	84
Equity	1	1
TOTAL LIABILITIES AND EQUITY	103	116
Variable Interest Entity, Primary Beneficiary | AEP TEXAS INC. | AEP Texas Restoration Funding | Intersegment Eliminations
ASSETS
Other Noncurrent Assets	(1)	(1)
Variable Interest Entity, Primary Beneficiary | APPALACHIAN POWER COMPANY | APCo Appalachian Consumer Rate Relief Funding
ASSETS
Current Assets	12	18
Net Property, Plant and Equipment	0	0
Other Noncurrent Assets	71	79
TOTAL ASSETS	83	97
LIABILITIES AND EQUITY
Current Liabilities	30	31
Noncurrent Liabilities	51	64
Equity	2	2
TOTAL LIABILITIES AND EQUITY	83	97
Variable Interest Entity, Primary Beneficiary | Transource Energy | SWEPCo Storm Recovery Funding
ASSETS
Current Assets	9	24
Net Property, Plant and Equipment	0	0
Other Noncurrent Assets	458	462
TOTAL ASSETS	467	486
LIABILITIES AND EQUITY
Current Liabilities	16	30
Noncurrent Liabilities	449	454
Equity	2	2
TOTAL LIABILITIES AND EQUITY	467	$ 486
Variable Interest Entity, Primary Beneficiary | Transource Energy | SWEPCo Storm Recovery Funding | Intersegment Eliminations
ASSETS
Other Noncurrent Assets	$ (16)