v3.26.3
RATE MATTERS - Impact to the Statements of Income Recorded by the Registrants (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Jun. 30, 2026
Mar. 31, 2026
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Sep. 30, 2026
Sep. 30, 2025
Regulatory Asset [Line Items]                
Total Revenues $ 6,832     $ 6,011     $ 18,297 $ 16,561
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation (2,087)     (1,981)     (5,808) (5,375)
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) 1,318     1,118     3,010 3,024
Income Tax Expense (Benefit) 125     139     221 13
Net Income 1,218 $ 747 $ 903 1,000 $ 1,289 $ 802 2,868 3,091
Net Income Attributable to Noncontrolling Interest 31     28     94 93
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
FERC 2021 PJM and SPP Transmission Formula Rate Challenge                
Regulatory Asset [Line Items]                
Total Revenues         270      
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation         (24)      
Other Operation         53      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT)         241      
Income Tax Expense (Benefit)         (313)      
Net Income         554      
Net Income Attributable to Noncontrolling Interest         55      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic         499      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted         499      
AEPTCo                
Regulatory Asset [Line Items]                
Total Revenues 594     558     1,760 1,827
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) 288     262     843 1,005
Income Tax Expense (Benefit) 62     57     184 (28)
Net Income 226 223 210 205 617 211 659 1,033
Net Income Attributable to Noncontrolling Interest 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
AEPTCo | FERC 2021 PJM and SPP Transmission Formula Rate Challenge                
Regulatory Asset [Line Items]                
Total Revenues         214      
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation         0      
Other Operation         0      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT)         214      
Income Tax Expense (Benefit)         (203)      
Net Income         417      
Net Income Attributable to Noncontrolling Interest         55      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic         362      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted         362      
APCo                
Regulatory Asset [Line Items]                
Total Revenues 1,133     1,057     3,216 3,177
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation (350)     (374)     (991) (1,072)
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) 131     113     388 412
Income Tax Expense (Benefit) 7     32     19 59
APCo | FERC 2021 PJM and SPP Transmission Formula Rate Challenge                
Regulatory Asset [Line Items]                
Total Revenues         6      
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation         (17)      
Other Operation         15      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT)         8      
Income Tax Expense (Benefit)         (21)      
Net Income         29      
Net Income Attributable to Noncontrolling Interest         0      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic         29      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted         29      
I&M                
Regulatory Asset [Line Items]                
Total Revenues 894     812     2,627 2,272
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) 119     139     399 297
Income Tax Expense (Benefit) 6     (11)     41 (35)
I&M | FERC 2021 PJM and SPP Transmission Formula Rate Challenge                
Regulatory Asset [Line Items]                
Total Revenues         11      
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation         0      
Other Operation         (6)      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT)         17      
Income Tax Expense (Benefit)         (28)      
Net Income         45      
Net Income Attributable to Noncontrolling Interest         0      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic         45      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted         45      
OPCo                
Regulatory Asset [Line Items]                
Total Revenues 1,208     1,070     3,305 2,993
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) 129     122     379 324
Income Tax Expense (Benefit) 17     22     41 59
OPCo | FERC 2021 PJM and SPP Transmission Formula Rate Challenge                
Regulatory Asset [Line Items]                
Total Revenues         0      
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation         0      
Other Operation         0      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT)         0      
Income Tax Expense (Benefit)         0      
Net Income         0      
Net Income Attributable to Noncontrolling Interest         0      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic         0      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted         0      
PSO                
Regulatory Asset [Line Items]                
Total Revenues 868     694     1,828 1,557
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation (231)     (295)     (575) (596)
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) 255     98     252 157
Income Tax Expense (Benefit) 21     (32)     (51) (64)
PSO | FERC 2021 PJM and SPP Transmission Formula Rate Challenge                
Regulatory Asset [Line Items]                
Total Revenues         6      
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation         0      
Other Operation         19      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT)         (13)      
Income Tax Expense (Benefit)         (16)      
Net Income         3      
Net Income Attributable to Noncontrolling Interest         0      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic         3      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted         3      
SWEPCo                
Regulatory Asset [Line Items]                
Total Revenues 770     724     1,929 1,825
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation (205)     (192)     (532) (575)
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT) 170     166     220 267
Income Tax Expense (Benefit) (18)     (24)     (111) (88)
Net Income 189 $ 86 $ 57 190 117 $ 49 332 356
Net Income Attributable to Noncontrolling Interest 1     1     2 3
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 188     189     330 353
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted $ 188     $ 189     $ 330 $ 353
SWEPCo | FERC 2021 PJM and SPP Transmission Formula Rate Challenge                
Regulatory Asset [Line Items]                
Total Revenues         27      
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation         0      
Other Operation         10      
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT)         17      
Income Tax Expense (Benefit)         (39)      
Net Income         56      
Net Income Attributable to Noncontrolling Interest         0      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic         56      
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted         $ 56