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Rate Matters Regulated Operations (Details) - USD ($)
$ in Millions
9 Months Ended
Sep. 30, 2024
Sep. 30, 2023
Dec. 31, 2023
Public Utilities, General Disclosures [Line Items]      
Net Investment $ 80,073.8   $ 76,693.4
Regulatory Assets, Noncurrent 5,318.9   5,092.4
Asset Impairments and Other Related Charges 142.5 $ 0.0  
Regulatory Assets, Current 399.7   514.0
AEP Texas Inc. [Member]      
Public Utilities, General Disclosures [Line Items]      
Net Investment 13,650.8   12,774.0
Regulatory Assets, Noncurrent 354.0   315.3
AEP Transmission Co [Member]      
Public Utilities, General Disclosures [Line Items]      
Net Investment 15,399.6   14,497.7
Regulatory Assets, Noncurrent 0.9   3.1
Appalachian Power Co [Member]      
Public Utilities, General Disclosures [Line Items]      
Net Investment 13,404.8   12,931.5
Regulatory Assets, Noncurrent 1,312.4   1,155.1
Regulatory Assets, Current 153.7   155.4
Indiana Michigan Power Co [Member]      
Public Utilities, General Disclosures [Line Items]      
Net Investment 7,773.0   7,629.0
Regulatory Assets, Noncurrent 572.6   406.3
Asset Impairments and Other Related Charges 13.4 0.0  
Regulatory Assets, Current 12.0   14.8
Ohio Power Co [Member]      
Public Utilities, General Disclosures [Line Items]      
Net Investment 9,779.0   9,299.9
Regulatory Assets, Noncurrent 394.9   455.0
Asset Impairments and Other Related Charges 52.9 $ 0.0  
Public Service Co Of Oklahoma [Member]      
Public Utilities, General Disclosures [Line Items]      
Net Investment 6,382.8   6,112.3
Regulatory Assets, Noncurrent 524.9   522.7
Regulatory Assets, Current 27.4   118.3
Public Service Co Of Oklahoma [Member] | Northeastern Plant, Unit 3 | Generating Units Probable of Abandonment [Member]      
Public Utilities, General Disclosures [Line Items]      
Net Investment 111.9    
Accelerated Depreciation Regulatory Asset 181.2    
Cost of Removal Regulatory Liability [1] $ 20.8    
Expected Retirement Date [2] 2026    
Depreciation [3] $ 15.7    
Southwestern Electric Power Co [Member]      
Public Utilities, General Disclosures [Line Items]      
Net Investment 8,908.2   8,558.4
Regulatory Assets, Noncurrent 1,120.3   1,131.8
Net Under-Recovered Fuel Costs 23.0    
Regulatory Assets, Current 106.6   170.8
Southwestern Electric Power Co [Member] | Dolet Hills Power Station [Member] | Louisiana Jurisdiction [Member]      
Public Utilities, General Disclosures [Line Items]      
Dolet Hills Prudency Disallowance 14.0    
Southwestern Electric Power Co [Member] | Dolet Hills Power Station and Related Fuel Operations      
Public Utilities, General Disclosures [Line Items]      
Share of Net Investment in Dolet Hills Power Station 76.0    
Southwestern Electric Power Co [Member] | Dolet Hills Power Station and Related Fuel Operations | Arkansas      
Public Utilities, General Disclosures [Line Items]      
Recovery of 2021 Dolet Hills Fuel Costs 20.0    
Southwestern Electric Power Co [Member] | Dolet Hills Power Station and Related Fuel Operations | Louisiana Jurisdiction [Member]      
Public Utilities, General Disclosures [Line Items]      
Recovery of 2021 Dolet Hills Fuel Costs 20.0    
Approved Deferral of Dolet Hills Fuel Costs 35.0    
Recommended Disallowance from Staff or Intervenors 55.0    
ALJ Recommended Customer Refund 55.0    
ALJ Recommended Denial of Recovery for Fuel Costs Deferral 35.0    
Dolet Hills Fuel Disallowance 11.0    
Remaining Dolet Fuel Reg Asset Recovered Over Three Years 24.0    
Southwestern Electric Power Co [Member] | Dolet Hills Power Station and Related Fuel Operations | Texas      
Public Utilities, General Disclosures [Line Items]      
Oxbow Mine Related Costs Recovery Request 48.0    
Southwestern Electric Power Co [Member] | Pirkey Power Plant and Related Fuel Operations      
Public Utilities, General Disclosures [Line Items]      
Share of Net Investment in Pirkey Power Plant 187.0    
Southwestern Electric Power Co [Member] | Pirkey Power Plant and Related Fuel Operations | Texas      
Public Utilities, General Disclosures [Line Items]      
Oxbow Mine Related Costs Recovery Request 33.0    
Southwestern Electric Power Co [Member] | Pirkey Generating Station (Unit No. 1) | Texas      
Public Utilities, General Disclosures [Line Items]      
Net Investment 69.0    
Southwestern Electric Power Co [Member] | Welsh Plant Unit 1 and 3 | Generating Units Probable of Abandonment [Member]      
Public Utilities, General Disclosures [Line Items]      
Net Investment 341.4    
Accelerated Depreciation Regulatory Asset 156.7    
Cost of Removal Regulatory Liability [4] $ 57.6    
Expected Retirement Date [5],[6] 2028    
Depreciation [3] $ 41.6    
Southwestern Electric Power Co [Member] | Dolet Hills Power Station | Arkansas      
Public Utilities, General Disclosures [Line Items]      
Asset Impairments and Other Related Charges 2.0    
Southwestern Electric Power Co [Member] | Dolet Hills Power Station | Texas      
Public Utilities, General Disclosures [Line Items]      
Asset Impairments and Other Related Charges 12.0    
Regulatory Assets Pending Final Regulatory Approval [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 1,283.6   874.4
Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 65.1   64.3
Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 427.7   125.5
Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 111.6   33.2
Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 0.3   23.6
Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 111.6   88.7
Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 477.8   444.9
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Storm Related Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 41.3   0.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 16.2   49.8
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | February 2021 Severe Storm Fuel Costs      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent [7] 75.9   97.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Pirkey Power Plant Accelerated Depreciation      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 120.8   114.4
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Welsh Unit 1 and 3 Accelerated Depreciation      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 156.7   125.6
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Storm Related Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 41.3   0.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 1.0   0.6
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 2.3   0.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 0.2   0.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Dolet Hills Power Station Accelerated Depreciation [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent [8] 11.8   12.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 1.0   26.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent [9] 75.9   97.2
Regulatory Assets, Current 37.0   37.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Pirkey Power Plant Accelerated Depreciation      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 120.8   114.4
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Welsh Unit 1 and 3 Accelerated Depreciation      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 156.7   125.6
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Plant Retirement Costs - Asset Retirement Obligation Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent [10] 340.4   25.9
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Storm Related Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 379.5   408.9
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 51.3   52.6
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | NOLC Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 82.9 [11]   0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | 2024-2025 Virginia Biennial Under-Earnings [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 18.6   0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Storm Related Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 16.6   37.7
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 1.4   11.7
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Texas Retail Electric Provider Bad Debt Expense      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 0.0   4.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Vegetation Management Programs      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 0.0   5.2
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Line Inspection Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 5.8   5.7
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | Plant Retirement Costs - Asset Retirement Obligation Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent [12] 266.9   25.9
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | Storm Related Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 126.5   91.5
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 14.7   7.5
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | 2024-2025 Virginia Biennial Under-Earnings [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 18.6   0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member] | Plant Retirement Costs - Asset Retirement Obligation Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 72.9 [13]   0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member] | Storm Related Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 7.4   29.7
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 4.4   3.3
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member] | NOLC Costs [Member] | Indiana [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 24.6 [14]   0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member] | Storm Related Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 0.0   23.6
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 0.1   0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member] | Storm Related Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 94.2   88.5
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 3.2   0.2
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member] | NOLC Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 14.2 [15]   0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Storm Related Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 49.0   56.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent 18.5   13.7
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | NOLC Costs [Member]      
Public Utilities, General Disclosures [Line Items]      
Regulatory Assets, Noncurrent $ 44.1 [16]   $ 0.0
[1] Includes Northeastern Plant, Unit 4, which was retired in 2016. Removal of Northeastern Plant, Unit 4, will be performed with the removal of Northeastern Plant, Unit 3, after retirement.
[2] Northeastern Plant, Unit 3 is currently being recovered through 2040.
[3] Represents the amount of annual depreciation that has been collected from customers over the prior 12-month period.
[4] Includes Welsh Plant, Unit 2, which was retired in 2016. Removal of Welsh Plant, Unit 2, will be performed with the removal of Welsh Plant, Units 1 and 3, after retirement.
[5] Represents projected retirement date of coal assets, units are being evaluated for conversion to natural gas after 2028.
[6] Unit 1 is being recovered through 2027 in the Louisiana jurisdiction and through 2037 in the Arkansas and Texas jurisdictions. Unit 3 is being recovered through 2032 in the Louisiana jurisdiction and through 2042 in the Arkansas and Texas jurisdictions.
[7] Includes $37 million of unrecovered winter storm fuel costs recorded as a current regulatory asset as of September 30, 2024 and December 31, 2023, respectively. See the “February 2021 Severe Winter Weather Impacts in SPP” section below for additional information.
[8] Amounts include the FERC jurisdiction
[9] Includes $37 million of unrecovered winter storm fuel costs recorded as a current regulatory asset as of September 30, 2024 and December 31, 2023, respectively. See the “February 2021 Severe Winter Weather Impacts in SPP” section below for additional information.
[10] See “Federal EPA’s Revised CCR Rule” section of Note 5 for additional information.
[11] In the second quarter of 2024, requests seeking to establish a recovery mechanism for these regulatory assets were filed in Indiana, Oklahoma and Texas. In Indiana and Oklahoma, certain intervenors have challenged the recovery, or have proposed ratemaking treatment that would offset the recovery, of the regulatory assets. In the third quarter of 2024, PUCT Staff and certain intervenors in Texas requested a hearing and direct testimony was filed by SWEPCo in October 2024.
[12] See “Federal EPA’s Revised CCR Rule” section of Note 5 for additional information.
[13] See “Federal EPA’s Revised CCR Rule” section of Note 5 for additional information.
[14] In the second quarter of 2024, a request seeking to establish a recovery mechanism for these regulatory assets were filed in Indiana. Certain intervenors have challenged the recovery, or have proposed ratemaking treatment that would offset the recovery, of the regulatory assets.
[15] In the second quarter of 2024, a request seeking to establish a recovery mechanism for these regulatory assets were filed in Oklahoma. Certain intervenors have challenged the recovery, or have proposed ratemaking treatment that would offset the recovery, of the regulatory assets.
[16] In the second quarter of 2024, a request seeking to establish a recovery mechanism for the Texas jurisdictional share of these regulatory assets were filed in Texas. In the third quarter of 2024, PUCT Staff and certain intervenors in Texas requested a hearing and direct testimony was filed by SWEPCo in October 2024.