LEASES - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Finance Leases
2026	$ 52
2027	41
2028	30
2029	21
2030	15
After 2030	21
Total Future Minimum Lease Payments	180
Less: Imputed Interest	25
Estimated Present Value of Future Minimum Lease Payments	155	$ 164
Operating Leases
2026	133
2027	114
2028	99
2029	71
2030	47
After 2030	607
Total Future Minimum Lease Payments	1,071
Less: Imputed Interest	393
Estimated Present Value of Future Minimum Lease Payments	678	596
AEP TEXAS INC.
Finance Leases
2026	8
2027	6
2028	4
2029	3
2030	2
After 2030	5
Total Future Minimum Lease Payments	28
Less: Imputed Interest	4
Estimated Present Value of Future Minimum Lease Payments	24	25
Operating Leases
2026	17
2027	14
2028	11
2029	7
2030	5
After 2030	7
Total Future Minimum Lease Payments	61
Less: Imputed Interest	7
Estimated Present Value of Future Minimum Lease Payments	54	56
AEPTCo
Finance Leases
2026	0
2027	0
2028	0
2029	0
2030	0
After 2030	0
Total Future Minimum Lease Payments	0
Less: Imputed Interest	0
Estimated Present Value of Future Minimum Lease Payments	0	0
Operating Leases
2026	1
2027	1
2028	1
2029	0
2030	0
After 2030	0
Total Future Minimum Lease Payments	3
Less: Imputed Interest	0
Estimated Present Value of Future Minimum Lease Payments	3	2
APCo
Finance Leases
2026	5
2027	3
2028	2
2029	2
2030	1
After 2030	2
Total Future Minimum Lease Payments	15
Less: Imputed Interest	1
Estimated Present Value of Future Minimum Lease Payments	14	19
Operating Leases
2026	20
2027	19
2028	16
2029	12
2030	8
After 2030	68
Total Future Minimum Lease Payments	143
Less: Imputed Interest	47
Estimated Present Value of Future Minimum Lease Payments	96	68
I&M
Finance Leases
2026	5
2027	5
2028	4
2029	3
2030	2
After 2030	3
Total Future Minimum Lease Payments	22
Less: Imputed Interest	5
Estimated Present Value of Future Minimum Lease Payments	17	22
Operating Leases
2026	19
2027	15
2028	13
2029	8
2030	2
After 2030	2
Total Future Minimum Lease Payments	59
Less: Imputed Interest	5
Estimated Present Value of Future Minimum Lease Payments	54	52
OPCo
Finance Leases
2026	4
2027	3
2028	2
2029	1
2030	1
After 2030	1
Total Future Minimum Lease Payments	12
Less: Imputed Interest	0
Estimated Present Value of Future Minimum Lease Payments	12	14
Operating Leases
2026	16
2027	14
2028	12
2029	7
2030	3
After 2030	3
Total Future Minimum Lease Payments	55
Less: Imputed Interest	5
Estimated Present Value of Future Minimum Lease Payments	50	60
PSO
Finance Leases
2026	4
2027	3
2028	2
2029	1
2030	1
After 2030	2
Total Future Minimum Lease Payments	13
Less: Imputed Interest	2
Estimated Present Value of Future Minimum Lease Payments	11	12
Operating Leases
2026	13
2027	12
2028	11
2029	9
2030	7
After 2030	178
Total Future Minimum Lease Payments	230
Less: Imputed Interest	97
Estimated Present Value of Future Minimum Lease Payments	133	112
SWEPCo
Finance Leases
2026	5
2027	4
2028	3
2029	3
2030	2
After 2030	4
Total Future Minimum Lease Payments	21
Less: Imputed Interest	4
Estimated Present Value of Future Minimum Lease Payments	17	19
Operating Leases
2026	21
2027	19
2028	17
2029	14
2030	12
After 2030	339
Total Future Minimum Lease Payments	422
Less: Imputed Interest	220
Estimated Present Value of Future Minimum Lease Payments	$ 202	$ 146