v3.26.1
RATE MATTERS - Impact to the Statements of Income Recorded by the Registrants (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
Regulatory Asset [Line Items]            
Total Revenues $ 5,445   $ 5,087   $ 11,465 $ 10,550
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation (1,603)   (1,541)   (3,721) (3,394)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT) 770   1,017   1,692 1,906
Income Tax Expense (Benefit) 52   (251)   96 (126)
Net Income 747 $ 903 1,289 $ 802 1,650 2,091
Net Income Attributable to Noncontrolling Interest 34   63   63 65
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
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 (LOSS) 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      
AEP TRANSMISSION COMPANY, LLC            
Regulatory Asset [Line Items]            
Total Revenues 588   742   1,166 1,269
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT) 285   471   555 743
Income Tax Expense (Benefit) 62   (146)   122 (85)
Net Income 223 210 617 211 433 828
Net Income Attributable to Noncontrolling Interest 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
AEP TRANSMISSION COMPANY, LLC | 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 (LOSS) 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      
APPALACHIAN POWER COMPANY            
Regulatory Asset [Line Items]            
Total Revenues 916   947   2,083 2,120
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation (277)   (291)   (641) (698)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT) 51   94   257 299
Income Tax Expense (Benefit) 1   (13)   12 27
APPALACHIAN POWER COMPANY | 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 (LOSS) 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      
INDIANA MICHIGAN POWER COMPANY            
Regulatory Asset [Line Items]            
Total Revenues 800   737   1,733 1,460
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT) 106   93   280 158
Income Tax Expense (Benefit) 9   (31)   35 (24)
INDIANA MICHIGAN POWER COMPANY | 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 (LOSS) 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      
OHIO POWER COMPANY            
Regulatory Asset [Line Items]            
Total Revenues 1,012   919   2,097 1,923
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT) 121   126   250 202
Income Tax Expense (Benefit) 12   23   24 37
OHIO POWER COMPANY | 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 (LOSS) 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      
PUBLIC SERVICE COMPANY OF OKLAHOMA            
Regulatory Asset [Line Items]            
Total Revenues 521   469   960 863
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation (180)   (172)   (344) (301)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT) 22   33   (3) 59
Income Tax Expense (Benefit) (32)   (30)   (72) (32)
PUBLIC SERVICE COMPANY OF OKLAHOMA | 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 (LOSS) 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      
SOUTHWESTERN ELECTRIC POWER COMPANY            
Regulatory Asset [Line Items]            
Total Revenues 588   570   1,159 1,101
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation (156)   (192)   (327) (383)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT) 42   58   50 101
Income Tax Expense (Benefit) (44)   (58)   (93) (64)
Net Income 86 $ 57 117 $ 49 143 166
Net Income Attributable to Noncontrolling Interest 0   1   1 2
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Basic 86   116   142 164
EARNINGS (LOSS) ATTRIBUTABLE TO AEP COMMON SHAREHOLDERS, Diluted $ 86   116   $ 142 $ 164
SOUTHWESTERN ELECTRIC POWER COMPANY | 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 (LOSS) 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