v3.26.1
BUSINESS SEGMENTS - Schedule of AEPTCo's Reportable Segment Information (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Segment Reporting [Line Items]          
Total Revenues $ 5,445 $ 5,087 $ 11,465 $ 10,550  
Other Operation and Maintenance 1,258 928 2,419 1,999  
Depreciation and Amortization 910 854 1,817 1,687  
Taxes Other Than Income Taxes 427 365 870 787  
Allowance for Equity Funds Used During Construction 75 57 145 114  
Interest Expense 585 489 1,137 984  
Income Tax Expense (Benefit) 52 (251) 96 (126)  
Other Segment Items 1 13 (14) (28)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 713 1,226 1,587 2,026  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 713 1,226 1,587 2,026  
Gross Property Additions 3,126 3,279 6,921 5,379  
Total Assets 121,570   121,570   $ 114,460
Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 5,445 5,087 11,465 10,550  
AEP TRANSMISSION COMPANY, LLC          
Segment Reporting [Line Items]          
Total Revenues 588 742 1,166 1,269  
Other Revenues 7   7    
Other Operation and Maintenance 53 42 104 76  
Depreciation and Amortization 128 119 256 233  
Taxes Other Than Income Taxes 86 76 174 150  
Interest Income 2 2 4 2  
Allowance for Equity Funds Used During Construction 26 21 48 43  
Interest Expense 64 57 129 112  
Income Tax Expense (Benefit) 62 (146) 122 (85)  
Other Segment Items 31 61 58 61  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 192 556 375 767  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 192 556 375 767  
Gross Property Additions 462 365 865 787  
Total Assets 19,076   19,076   17,999
AEP TRANSMISSION COMPANY, LLC | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 107 145 217 249  
AEP TRANSMISSION COMPANY, LLC | Affiliated Entity          
Segment Reporting [Line Items]          
Total Revenues 474 597 942 1,020  
Operating Segments          
Segment Reporting [Line Items]          
Total Revenues 6,022 5,787 12,621 11,741  
Other Operation and Maintenance 1,773 1,568 3,432 3,096  
Depreciation and Amortization 914 859 1,826 1,697  
Taxes Other Than Income Taxes 420 359 855 774  
Allowance for Equity Funds Used During Construction 75 57 145 114  
Interest Expense 451 362 871 733  
Income Tax Expense (Benefit) 65 (207) 146 (25)  
Other Segment Items (4) 12 (31) (33)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 828 1,297 1,811 2,123  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 828 1,297 1,811 2,123  
Gross Property Additions 3,014 3,283 6,656 5,342  
Total Assets 120,254   120,254   112,772
Operating Segments | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 5,440 5,084 11,457 10,531  
Operating Segments | State Transcos | AEP TRANSMISSION COMPANY, LLC          
Segment Reporting [Line Items]          
Total Revenues 588 742 1,166 1,269  
Other Revenues 7   7    
Other Operation and Maintenance 53 42 104 76  
Depreciation and Amortization 128 119 256 233  
Taxes Other Than Income Taxes 86 76 174 150  
Interest Income 0 1 1 1  
Allowance for Equity Funds Used During Construction 26 21 48 43  
Interest Expense 63 77 128 161  
Income Tax Expense (Benefit) 62 (156) 122 (95)  
Other Segment Items 0 0 0 0  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 222 606 431 788  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 222 606 431 788  
Gross Property Additions 462 365 865 787  
Total Assets 19,024   19,024   17,983
Operating Segments | State Transcos | AEP TRANSMISSION COMPANY, LLC | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 107 145 217 249  
Operating Segments | State Transcos | AEP TRANSMISSION COMPANY, LLC | Affiliated Entity          
Segment Reporting [Line Items]          
Total Revenues 474 597 942 1,020  
Corporate and Other          
Segment Reporting [Line Items]          
Total Revenues 30 30 61 74  
Other Operation and Maintenance 27 20 65 36  
Depreciation and Amortization (4) (5) (9) (10)  
Taxes Other Than Income Taxes 0 0 0 1  
Allowance for Equity Funds Used During Construction 0 0 0 0  
Interest Expense 170 151 336 298  
Income Tax Expense (Benefit) (13) (44) (50) (101)  
Other Segment Items (31) (23) (53) (42)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic (115) (71) (224) (97)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted (115) (71) (224) (97)  
Gross Property Additions 136 6 283 36  
Total Assets 7,092   7,092   6,733
Corporate and Other | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 5 3 8 19  
Corporate and Other | AEP TRANSMISSION COMPANY, LLC          
Segment Reporting [Line Items]          
Total Revenues 0 0 0 0  
Other Revenues 0   0    
Other Operation and Maintenance 0 0 0 0  
Depreciation and Amortization 0 0 0 0  
Taxes Other Than Income Taxes 0 0 0 0  
Interest Income 73 84 146 173  
Allowance for Equity Funds Used During Construction 0 0 0 0  
Interest Expense 72 63 144 123  
Income Tax Expense (Benefit) 0 10 0 10  
Other Segment Items 31 61 58 61  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic (30) (50) (56) (21)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted (30) (50) (56) (21)  
Gross Property Additions 0 0 0 0  
Total Assets 7,252   7,252   6,766
Corporate and Other | AEP TRANSMISSION COMPANY, LLC | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 0 0 0 0  
Corporate and Other | AEP TRANSMISSION COMPANY, LLC | Affiliated Entity          
Segment Reporting [Line Items]          
Total Revenues 0 0 0 0  
Reconciling Adjustments          
Segment Reporting [Line Items]          
Total Revenues (607) (730) (1,217) (1,265)  
Other Operation and Maintenance (542) (660) (1,078) (1,133)  
Depreciation and Amortization 0 0 0 0  
Taxes Other Than Income Taxes 7 6 15 12  
Allowance for Equity Funds Used During Construction 0 0 0 0  
Interest Expense (36) (24) (70) (47)  
Income Tax Expense (Benefit) 0 0 0 0  
Other Segment Items 36 24 70 47  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 0 0 0 0  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 0 0 0 0  
Gross Property Additions (24) (10) (18) 1  
Total Assets (5,776)   (5,776)   (5,045)
Reconciling Adjustments | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 0 0 0 0  
Reconciling Adjustments | AEP TRANSMISSION COMPANY, LLC          
Segment Reporting [Line Items]          
Total Revenues 0 0 0 0  
Other Revenues 0   0    
Other Operation and Maintenance 0 0 0 0  
Depreciation and Amortization 0 0 0 0  
Taxes Other Than Income Taxes 0 0 0 0  
Interest Income (71) (83) (143) (172)  
Allowance for Equity Funds Used During Construction 0 0 0 0  
Interest Expense (71) (83) (143) (172)  
Income Tax Expense (Benefit) 0 0 0 0  
Other Segment Items 0 0 0 0  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 0 0 0 0  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 0 0 0 0  
Gross Property Additions 0 0 0 0  
Total Assets (7,200)   (7,200)   $ (6,750)
Reconciling Adjustments | AEP TRANSMISSION COMPANY, LLC | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 0 0 0 0  
Reconciling Adjustments | AEP TRANSMISSION COMPANY, LLC | Affiliated Entity          
Segment Reporting [Line Items]          
Total Revenues $ 0 $ 0 $ 0 $ 0