LEASES - Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Deferred credits and other noncurrent liabilities	Deferred credits and other noncurrent liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities, Deferred credits and other noncurrent liabilities	Other Current Liabilities, Deferred credits and other noncurrent liabilities
Net Property, Plant and Equipment Under Finance Leases	$ 155	$ 164
Obligations Under Finance Leases:
Noncurrent Liability	112	117
Liability Due Within One Year	43	47
Total Obligations Under Finance Leases	155	164
Operating Lease Assets	661	580
Obligations Under Operating Leases:
Noncurrent Liability	578	504
Liability Due Within One Year	100	92
Total Obligations Under Operating Leases	$ 678	$ 596
AEP TEXAS INC.
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Deferred credits and other noncurrent liabilities	Deferred credits and other noncurrent liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities, Deferred credits and other noncurrent liabilities	Other Current Liabilities, Deferred credits and other noncurrent liabilities
Net Property, Plant and Equipment Under Finance Leases	$ 24	$ 25
Obligations Under Finance Leases:
Noncurrent Liability	17	18
Liability Due Within One Year	7	7
Total Obligations Under Finance Leases	24	25
Operating Lease Assets	52	54
Obligations Under Operating Leases:
Noncurrent Liability	40	43
Liability Due Within One Year	14	13
Total Obligations Under Operating Leases	$ 54	$ 56
AEPTCo
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Deferred credits and other noncurrent liabilities	Deferred credits and other noncurrent liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities, Deferred credits and other noncurrent liabilities	Other Current Liabilities, Deferred credits and other noncurrent liabilities
Net Property, Plant and Equipment Under Finance Leases	$ 0	$ 0
Obligations Under Finance Leases:
Noncurrent Liability	0	0
Liability Due Within One Year	0	0
Total Obligations Under Finance Leases	0	0
Operating Lease Assets	3	2
Obligations Under Operating Leases:
Noncurrent Liability	2	1
Liability Due Within One Year	1	1
Total Obligations Under Operating Leases	$ 3	$ 2
APCo
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Deferred credits and other noncurrent liabilities	Deferred credits and other noncurrent liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities, Deferred credits and other noncurrent liabilities	Other Current Liabilities, Deferred credits and other noncurrent liabilities
Net Property, Plant and Equipment Under Finance Leases	$ 15	$ 19
Obligations Under Finance Leases:
Noncurrent Liability	10	11
Liability Due Within One Year	4	8
Total Obligations Under Finance Leases	14	19
Operating Lease Assets	95	67
Obligations Under Operating Leases:
Noncurrent Liability	81	54
Liability Due Within One Year	15	14
Total Obligations Under Operating Leases	$ 96	$ 68
I&M
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Deferred credits and other noncurrent liabilities	Deferred credits and other noncurrent liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities, Deferred credits and other noncurrent liabilities	Other Current Liabilities, Deferred credits and other noncurrent liabilities
Net Property, Plant and Equipment Under Finance Leases	$ 18	$ 22
Obligations Under Finance Leases:
Noncurrent Liability	13	16
Liability Due Within One Year	4	6
Total Obligations Under Finance Leases	17	22
Operating Lease Assets	52	52
Obligations Under Operating Leases:
Noncurrent Liability	37	40
Liability Due Within One Year	17	12
Total Obligations Under Operating Leases	$ 54	$ 52
OPCo
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Deferred credits and other noncurrent liabilities	Deferred credits and other noncurrent liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities, Deferred credits and other noncurrent liabilities	Other Current Liabilities, Deferred credits and other noncurrent liabilities
Net Property, Plant and Equipment Under Finance Leases	$ 13	$ 14
Obligations Under Finance Leases:
Noncurrent Liability	8	10
Liability Due Within One Year	4	4
Total Obligations Under Finance Leases	12	14
Operating Lease Assets	50	60
Obligations Under Operating Leases:
Noncurrent Liability	37	48
Liability Due Within One Year	13	12
Total Obligations Under Operating Leases	$ 50	$ 60
PSO
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Deferred credits and other noncurrent liabilities	Deferred credits and other noncurrent liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities, Deferred credits and other noncurrent liabilities	Other Current Liabilities, Deferred credits and other noncurrent liabilities
Net Property, Plant and Equipment Under Finance Leases	$ 11	$ 12
Obligations Under Finance Leases:
Noncurrent Liability	8	9
Liability Due Within One Year	3	3
Total Obligations Under Finance Leases	11	12
Operating Lease Assets	126	106
Obligations Under Operating Leases:
Noncurrent Liability	122	102
Liability Due Within One Year	11	10
Total Obligations Under Operating Leases	$ 133	$ 112
SWEPCo
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities	Other Current Liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Deferred credits and other noncurrent liabilities	Deferred credits and other noncurrent liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Current Liabilities, Deferred credits and other noncurrent liabilities	Other Current Liabilities, Deferred credits and other noncurrent liabilities
Net Property, Plant and Equipment Under Finance Leases	$ 17	$ 19
Obligations Under Finance Leases:
Noncurrent Liability	13	15
Liability Due Within One Year	4	4
Total Obligations Under Finance Leases	17	19
Operating Lease Assets	198	141
Obligations Under Operating Leases:
Noncurrent Liability	195	138
Liability Due Within One Year	7	8
Total Obligations Under Operating Leases	202	146
Generation
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	48	74
Generation | AEP TEXAS INC.
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	0	0
Generation | AEPTCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	0	0
Generation | APCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	40	42
Generation | I&M
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	5	17
Generation | OPCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	0	0
Generation | PSO
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	1	1
Generation | SWEPCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	2	2
Other Property, Plant and Equipment
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	291	284
Other Property, Plant and Equipment | AEP TEXAS INC.
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	53	53
Other Property, Plant and Equipment | AEPTCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	0	0
Other Property, Plant and Equipment | APCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	19	19
Other Property, Plant and Equipment | I&M
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	38	38
Other Property, Plant and Equipment | OPCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	28	30
Other Property, Plant and Equipment | PSO
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	23	23
Other Property, Plant and Equipment | SWEPCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	29	30
Total Property, Plant and Equipment
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	339	358
Total Property, Plant and Equipment | AEP TEXAS INC.
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	53	53
Total Property, Plant and Equipment | AEPTCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	0	0
Total Property, Plant and Equipment | APCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	59	61
Total Property, Plant and Equipment | I&M
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	43	55
Total Property, Plant and Equipment | OPCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	28	30
Total Property, Plant and Equipment | PSO
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	24	24
Total Property, Plant and Equipment | SWEPCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	31	32
Accumulated Amortization
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	184	194
Accumulated Amortization | AEP TEXAS INC.
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	29	28
Accumulated Amortization | AEPTCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	0	0
Accumulated Amortization | APCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	44	42
Accumulated Amortization | I&M
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	25	33
Accumulated Amortization | OPCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	15	16
Accumulated Amortization | PSO
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	13	12
Accumulated Amortization | SWEPCo
Lessee, Lease, Description [Line Items]
Net Property, Plant and Equipment Under Finance Leases	$ 14	$ 13