v3.26.3
BUSINESS SEGMENTS - Schedule of AEPTCo's Reportable Segment Information (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Segment Reporting [Line Items]          
Total Revenues $ 6,832 $ 6,011 $ 18,297 $ 16,561  
Other Operation and Maintenance 1,475 1,203 3,894 3,202  
Depreciation and Amortization 1,025 879 2,842 2,566  
Taxes Other Than Income Taxes 433 426 1,303 1,213  
Allowance for Equity Funds Used During Construction 81 59 226 173  
Interest Expense 606 509 1,743 1,493  
Income Tax Expense (Benefit) 125 139 221 13  
Other Segment Items 0 (18) (14) (46)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 1,187 972 2,774 2,998  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 1,187 972 2,774 2,998  
Gross Property Additions 4,580 2,279 11,501 7,658  
Total Assets 125,695   125,695   $ 114,460
Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 6,832 6,011 18,297 16,561  
AEP TRANSMISSION COMPANY, LLC          
Segment Reporting [Line Items]          
Total Revenues 594 558 1,760 1,827  
Other Revenues 2   9    
Other Operation and Maintenance 60 51 164 127  
Depreciation and Amortization 133 121 389 354  
Taxes Other Than Income Taxes 76 86 250 236  
Interest Income 3 1 7 3  
Allowance for Equity Funds Used During Construction 27 22 75 65  
Interest Expense 67 61 196 173  
Income Tax Expense (Benefit) 62 57 184 (28)  
Other Segment Items 30 26 88 87  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 196 179 571 946  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 196 179 571 946  
Gross Property Additions 875 358 1,740 1,145  
Total Assets 19,469   19,469   17,999
AEP TRANSMISSION COMPANY, LLC | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 112 108 329 357  
AEP TRANSMISSION COMPANY, LLC | Affiliated Entity          
Segment Reporting [Line Items]          
Total Revenues 480 450 1,422 1,470  
Operating Segments          
Segment Reporting [Line Items]          
Total Revenues 7,434 6,561 20,055 18,302  
Other Operation and Maintenance 1,996 1,710 5,428 4,806  
Depreciation and Amortization 1,030 884 2,856 2,581  
Taxes Other Than Income Taxes 426 421 1,281 1,195  
Allowance for Equity Funds Used During Construction 81 59 226 173  
Interest Expense 472 390 1,343 1,123  
Income Tax Expense (Benefit) 166 109 312 84  
Other Segment Items (18) (20) (49) (53)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 1,296 1,090 3,107 3,213  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 1,296 1,090 3,107 3,213  
Gross Property Additions 4,446 2,285 11,102 7,627  
Total Assets 124,535   124,535   112,772
Operating Segments | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 6,831 6,005 18,288 16,536  
Operating Segments | State Transcos | AEP TRANSMISSION COMPANY, LLC          
Segment Reporting [Line Items]          
Total Revenues 594 558 1,760 1,827  
Other Revenues 2   9    
Other Operation and Maintenance 60 51 164 127  
Depreciation and Amortization 133 121 389 354  
Taxes Other Than Income Taxes 76 86 250 236  
Interest Income 0 1 1 2  
Allowance for Equity Funds Used During Construction 27 22 75 65  
Interest Expense 68 62 196 223  
Income Tax Expense (Benefit) 60 56 182 (39)  
Other Segment Items 0 0 0 0  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 224 205 655 993  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted 224 205 655 993  
Gross Property Additions 875 358 1,740 1,145  
Total Assets 19,391   19,391   17,983
Operating Segments | State Transcos | AEP TRANSMISSION COMPANY, LLC | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 112 108 329 357  
Operating Segments | State Transcos | AEP TRANSMISSION COMPANY, LLC | Affiliated Entity          
Segment Reporting [Line Items]          
Total Revenues 480 450 1,422 1,470  
Corporate and Other          
Segment Reporting [Line Items]          
Total Revenues 38 36 99 110  
Other Operation and Maintenance 41 8 106 44  
Depreciation and Amortization (5) (5) (14) (15)  
Taxes Other Than Income Taxes 1 0 1 1  
Allowance for Equity Funds Used During Construction 0 0 0 0  
Interest Expense 176 140 512 438  
Income Tax Expense (Benefit) (41) 30 (91) (71)  
Other Segment Items (24) (19) (77) (61)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic (109) (118) (333) (215)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted (109) (118) (333) (215)  
Gross Property Additions 170 18 453 54  
Total Assets 7,136   7,136   6,733
Corporate and Other | Nonrelated Party          
Segment Reporting [Line Items]          
Total Revenues 1 6 9 25  
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 78 66 224 239  
Allowance for Equity Funds Used During Construction 0 0 0 0  
Interest Expense 74 65 218 188  
Income Tax Expense (Benefit) 2 1 2 11  
Other Segment Items 30 26 88 87  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic (28) (26) (84) (47)  
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted (28) (26) (84) (47)  
Gross Property Additions 0 0 0 0  
Total Assets 7,111   7,111   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 (640) (586) (1,857) (1,851)  
Other Operation and Maintenance (562) (515) (1,640) (1,648)  
Depreciation and Amortization 0 0 0 0  
Taxes Other Than Income Taxes 6 5 21 17  
Allowance for Equity Funds Used During Construction 0 0 0 0  
Interest Expense (42) (21) (112) (68)  
Income Tax Expense (Benefit) 0 0 0 0  
Other Segment Items 42 21 112 68  
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 (36) (24) (54) (23)  
Total Assets (5,976)   (5,976)   (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 (75) (66) (218) (238)  
Allowance for Equity Funds Used During Construction 0 0 0 0  
Interest Expense (75) (66) (218) (238)  
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 (7,033)   (7,033)   $ (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