ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Depreciation and Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and Amortization of Property, Plant and Equipment	$ 3,325	$ 3,149	$ 2,927
Amortization of Certain Securitized Assets	46	91	92
Amortization of Regulatory Assets and Liabilities	9	50	71
Total Depreciation and Amortization	3,380	3,290	3,090
AEP Texas
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and Amortization of Property, Plant and Equipment	420	406	380
Amortization of Certain Securitized Assets	18	91	92
Amortization of Regulatory Assets and Liabilities	3	(3)	(3)
Total Depreciation and Amortization	441	494	469
AEPTCo
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and Amortization of Property, Plant and Equipment	478	431	394
Amortization of Certain Securitized Assets	0	0	0
Amortization of Regulatory Assets and Liabilities	0	0	0
Total Depreciation and Amortization	478	431	394
APCo
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and Amortization of Property, Plant and Equipment	652	600	571
Amortization of Certain Securitized Assets	0	0	0
Amortization of Regulatory Assets and Liabilities	(20)	2	1
Total Depreciation and Amortization	632	602	572
I&M
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and Amortization of Property, Plant and Equipment	471	456	440
Amortization of Certain Securitized Assets	0	0	0
Amortization of Regulatory Assets and Liabilities	43	25	30
Total Depreciation and Amortization	514	481	470
OPCo
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and Amortization of Property, Plant and Equipment	380	386	316
Amortization of Certain Securitized Assets	0	0	0
Amortization of Regulatory Assets and Liabilities	0	0	0
Total Depreciation and Amortization	380	386	316
PSO
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and Amortization of Property, Plant and Equipment	293	263	241
Amortization of Certain Securitized Assets	0	0	0
Amortization of Regulatory Assets and Liabilities	(33)	9	15
Total Depreciation and Amortization	260	272	256
SWEPCo
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and Amortization of Property, Plant and Equipment	391	375	323
Amortization of Certain Securitized Assets	20	0	0
Amortization of Regulatory Assets and Liabilities	18	14	20
Total Depreciation and Amortization	$ 429	$ 389	$ 343