v3.26.1
RATE MATTERS - Regulatory Assets Pending Final Approval (Details) - USD ($)
$ in Millions
Jun. 30, 2026
May 31, 2026
Mar. 31, 2026
Dec. 31, 2025
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets $ 5,021     $ 4,804
AEP TEXAS INC.        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 444     402
AEP TRANSMISSION COMPANY, LLC        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 84     73
APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 1,407     1,439
INDIANA MICHIGAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 553     585
PUBLIC SERVICE COMPANY OF OKLAHOMA        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 693     637
SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 955     903
Total Regulatory Assets Pending Final Regulatory Approval        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 1,426     1,307
Total Regulatory Assets Pending Final Regulatory Approval | AEP TEXAS INC.        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 221     181
Total Regulatory Assets Pending Final Regulatory Approval | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 376     440
Total Regulatory Assets Pending Final Regulatory Approval | INDIANA MICHIGAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 138     118
Total Regulatory Assets Pending Final Regulatory Approval | PUBLIC SERVICE COMPANY OF OKLAHOMA        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 116     84
Total Regulatory Assets Pending Final Regulatory Approval | SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 524     445
Total Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | AEP TRANSMISSION COMPANY, LLC        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 9     9
Welsh Plant, Units 1 and 3 Accelerated Depreciation | Regulatory Assets Currently Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 249     220
Welsh Plant, Units 1 and 3 Accelerated Depreciation | Regulatory Assets Currently Earning a Return | SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 249     220
UTM Deferred Costs | Regulatory Assets Currently Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 65     56
UTM Deferred Costs | Regulatory Assets Currently Earning a Return | AEP TEXAS INC.        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 65     56
UTM Deferred Costs | Regulatory Assets Currently Not Earning a Return | AEP TEXAS INC.        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 7     0
Pirkey Plant Accelerated Depreciation | Regulatory Assets Currently Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 61     93
Pirkey Plant Accelerated Depreciation | Regulatory Assets Currently Earning a Return | SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 61     93
Storm-Related Costs | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
Regulatory asset, requested to be financed through securitization, approved   $ 141    
Storm-Related Costs | Regulatory Assets Currently Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 47     43
Storm-Related Costs | Regulatory Assets Currently Earning a Return | AEP TEXAS INC.        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 41     41
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 300     191
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | AEP TEXAS INC.        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 39     31
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 64     39
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | INDIANA MICHIGAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 46     29
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | PUBLIC SERVICE COMPANY OF OKLAHOMA        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 34     25
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 92     43
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | West Virginia        
Regulatory Asset [Line Items]        
Regulatory asset, requested to be financed through securitization     $ 40  
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | West Virginia | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
Regulatory asset, requested to be financed through securitization     $ 40  
System Resiliency Plan Deferred Costs | Regulatory Assets Currently Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 46     17
System Resiliency Plan Deferred Costs | Regulatory Assets Currently Earning a Return | AEP TEXAS INC.        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 23     17
System Resiliency Plan Deferred Costs | Regulatory Assets Currently Earning a Return | SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 23     1
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 5     6
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 2     2
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Earning a Return | INDIANA MICHIGAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 4     4
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Earning a Return | SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 5     2
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 165     136
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | AEP TEXAS INC.        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 10     9
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 27     18
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | INDIANA MICHIGAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 7     7
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | PUBLIC SERVICE COMPANY OF OKLAHOMA        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 1     8
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 22     20
Plant Retirement Costs – Asset Retirement Obligation Costs | Regulatory Assets Currently Not Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 283     257
Plant Retirement Costs – Asset Retirement Obligation Costs | Regulatory Assets Currently Not Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 185     169
Plant Retirement Costs – Asset Retirement Obligation Costs | Regulatory Assets Currently Not Earning a Return | INDIANA MICHIGAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 81     78
Plant Retirement Costs – Asset Retirement Obligation Costs | Regulatory Assets Currently Not Earning a Return | PUBLIC SERVICE COMPANY OF OKLAHOMA        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 12     6
NOLC Costs | Regulatory Assets Currently Not Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 85     89
NOLC Costs | Regulatory Assets Currently Not Earning a Return | PUBLIC SERVICE COMPANY OF OKLAHOMA        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 19     23
NOLC Costs | Regulatory Assets Currently Not Earning a Return | SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 65     66
2024-2025 Virginia Biennial Under-Earnings | Regulatory Assets Currently Not Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 51     172
2024-2025 Virginia Biennial Under-Earnings | Regulatory Assets Currently Not Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 51     172
Vegetation Management Costs | Regulatory Assets Currently Not Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 33     0
Vegetation Management Costs | Regulatory Assets Currently Not Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 13     0
Deferred Pension and OPEB Costs | Regulatory Assets Currently Not Earning a Return        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 36     27
Deferred Pension and OPEB Costs | Regulatory Assets Currently Not Earning a Return | AEP TEXAS INC.        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 36     27
2026-2027 Virginia Biennial Under-Earnings | Regulatory Assets Currently Not Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 18     0
Pension Settlement | Regulatory Assets Currently Not Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 16     16
Income Taxes, Net | Regulatory Assets Currently Earning a Return | SOUTHWESTERN ELECTRIC POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 7     0
Income Taxes, Net | Regulatory Assets Currently Not Earning a Return | AEP TRANSMISSION COMPANY, LLC        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 9     9
Virginia Corporate Alternative Minimum Tax | Regulatory Assets Currently Not Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 0     13
West Virginia Corporate Alternative Minimum Tax | Regulatory Assets Currently Not Earning a Return | APPALACHIAN POWER COMPANY        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 0     11
Generation PBA and Delayed Retirement Deferral | Regulatory Assets Currently Not Earning a Return | PUBLIC SERVICE COMPANY OF OKLAHOMA        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets 26     13
Oklahoma Senate Bill 998 Deferral | Regulatory Assets Currently Not Earning a Return | PUBLIC SERVICE COMPANY OF OKLAHOMA        
Regulatory Asset [Line Items]        
 Noncurrent Regulatory Assets $ 24     $ 9