BUSINESS SEGMENTS - AEPTCo's Reportable Segment Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Total Revenues	$ 21,876	$ 19,721	$ 18,982
Other Operation and Maintenance	4,449	4,452	4,087
Depreciation and Amortization	3,380	3,290	3,090
Taxes Other Than Income Taxes	1,631	1,596	1,492
Allowance for equity funds used during construction	245	211	175
Interest Expense	2,026	1,863	1,807
Income Tax Expense	129	(39)	55
Other Segment Items	(70)	(182)	(280)
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Diluted	3,580	2,967	2,208
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Basic	3,580	2,967	2,208
Gross Property Additions	11,906	8,030	7,533
Total Assets	114,460	103,078
Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	21,876	19,721	18,982
Operating Segments
Segment Reporting Information [Line Items]
Total Revenues	24,105	21,501	20,524
Other Operation and Maintenance	6,479	5,987	5,434
Depreciation and Amortization	3,400	3,312	3,107
Taxes Other Than Income Taxes	1,606	1,576	1,477
Allowance for equity funds used during construction	245	211	175
Interest Expense	1,529	1,369	1,408
Income Tax Expense	250	114	138
Other Segment Items	(83)	(194)	(296)
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Diluted	3,869	3,258	2,466
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Basic	3,869	3,258	2,466
Gross Property Additions	11,938	7,595	7,496
Total Assets	112,772	101,507
Operating Segments | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	21,843	19,664	18,921
Corporate and Other
Segment Reporting Information [Line Items]
Total Revenues	144	183	168
Other Operation and Maintenance	74	137	103
Depreciation and Amortization	(20)	(22)	(17)
Taxes Other Than Income Taxes	1	0	0
Allowance for equity funds used during construction	0	0	0
Interest Expense	592	613	594
Income Tax Expense	(121)	(153)	(83)
Other Segment Items	(82)	(107)	(179)
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Diluted	(289)	(291)	(258)
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Basic	(289)	(291)	(258)
Gross Property Additions	38	467	36
Total Assets	6,733	5,551
Corporate and Other | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	33	57	61
Reconciling Adjustments
Segment Reporting Information [Line Items]
Total Revenues	(2,373)	(1,963)	(1,710)
Other Operation and Maintenance	(2,104)	(1,672)	(1,450)
Depreciation and Amortization	0	0	0
Taxes Other Than Income Taxes	24	20	15
Allowance for equity funds used during construction	0	0	0
Interest Expense	(95)	(119)	(195)
Income Tax Expense	0	0	0
Other Segment Items	95	119	195
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Diluted	0	0	0
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Basic	0	0	0
Gross Property Additions	(70)	(32)	1
Total Assets	(5,045)	(3,980)
Reconciling Adjustments | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
AEP TRANSMISSION COMPANY, LLC
Segment Reporting Information [Line Items]
Total Revenues	2,319	1,891	1,671
Other Operation and Maintenance	185	158	129
Depreciation and Amortization	478	431	394
Taxes Other Than Income Taxes	321	309	283
Interest Income	5	10	8
Allowance for equity funds used during construction	93	89	83
Interest Expense	234	214	195
Income Tax Expense	15	190	147
Other Segment Items	109
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Diluted	1,075	688	614
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Basic	1,075	688	614
Gross Property Additions	1,579	1,482	1,503
Total Assets	17,999	16,370
AEP TRANSMISSION COMPANY, LLC | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	450	379	354
AEP TRANSMISSION COMPANY, LLC | Affiliated Entity
Segment Reporting Information [Line Items]
Total Revenues	1,869	1,512	1,317
AEP TRANSMISSION COMPANY, LLC | Corporate and Other
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
Other Operation and Maintenance	0	2	0
Depreciation and Amortization	0	0	0
Taxes Other Than Income Taxes	0	0	0
Interest Income	308	241	218
Allowance for equity funds used during construction	0	0	0
Interest Expense	257	239	215
Income Tax Expense	11	0	2
Other Segment Items	109
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Diluted	(69)	0	1
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Basic	(69)	0	1
Gross Property Additions	0	0	0
Total Assets	6,766	8,670
AEP TRANSMISSION COMPANY, LLC | Corporate and Other | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
AEP TRANSMISSION COMPANY, LLC | Corporate and Other | Affiliated Entity
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
AEP TRANSMISSION COMPANY, LLC | Reconciling Adjustments
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
Other Operation and Maintenance	0	0	0
Depreciation and Amortization	0	0	0
Taxes Other Than Income Taxes	0	0	0
Interest Income	(306)	(239)	(214)
Allowance for equity funds used during construction	0	0	0
Interest Expense	(306)	(239)	(214)
Income Tax Expense	0	0	0
Other Segment Items	0
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Diluted	0	0	0
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Basic	0	0	0
Gross Property Additions	0	0	0
Total Assets	(6,750)	(9,188)
AEP TRANSMISSION COMPANY, LLC | Reconciling Adjustments | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
AEP TRANSMISSION COMPANY, LLC | Reconciling Adjustments | Affiliated Entity
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
AEP TRANSMISSION COMPANY, LLC | State Transcos | Operating Segments
Segment Reporting Information [Line Items]
Total Revenues	2,319	1,891	1,671
Other Operation and Maintenance	185	156	129
Depreciation and Amortization	478	431	394
Taxes Other Than Income Taxes	321	309	283
Interest Income	3	8	4
Allowance for equity funds used during construction	93	89	83
Interest Expense	283	214	194
Income Tax Expense	4	190	145
Other Segment Items	0
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Diluted	1,144	688	613
EARNINGS ATTRIBUTABLE TO AEP MEMBER, Basic	1,144	688	613
Gross Property Additions	1,579	1,482	1,503
Total Assets	17,983	16,888
AEP TRANSMISSION COMPANY, LLC | State Transcos | Operating Segments | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	450	379	354
AEP TRANSMISSION COMPANY, LLC | State Transcos | Operating Segments | Affiliated Entity
Segment Reporting Information [Line Items]
Total Revenues	$ 1,869	$ 1,512	$ 1,317