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RATE MATTERS - Regulatory Assets Pending Final Approval (Details) - USD ($) $ in Millions | 1 Months Ended |  |
--- | --- | --- | ---
Feb. 28, 2025 | Jan. 31, 2025 | Mar. 31, 2025 | Dec. 31, 2024
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | $ 5,133.6 | $ 5,129.2
Regulatory assets, current |  |  | 537.4 | 445.9
AEP Texas |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 343.4 | 353.6
APCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 1,436.6 | 1,366.0
Regulatory assets, current |  |  | 135.4 | 148.1
I&M |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 550.0 | 548.1
Regulatory assets, current |  |  | 7.0 | 10.6
OPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 318.9 | 379.1
PSO |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 529.8 | 527.8
Regulatory assets, current |  |  | 141.0 | 64.7
SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 919.4 | 921.3
Regulatory assets, current |  |  | 111.4 | 106.6
Total Regulatory Assets Pending Final Regulatory Approval |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 1,459.6 | 1,348.0
Total Regulatory Assets Pending Final Regulatory Approval | AEP Texas |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 85.3 | 77.1
Total Regulatory Assets Pending Final Regulatory Approval | APCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 627.2 | 535.5
Total Regulatory Assets Pending Final Regulatory Approval | I&M |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 89.7 | 115.0
Total Regulatory Assets Pending Final Regulatory Approval | OPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 0.6 | 0.5
Total Regulatory Assets Pending Final Regulatory Approval | PSO |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 36.4 | 30.3
Total Regulatory Assets Pending Final Regulatory Approval | SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 511.3 | 491.4
Welsh Plant, Units 1 and 3 Accelerated Depreciation | Regulatory Assets Currently Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 180.5 | 168.6
Welsh Plant, Units 1 and 3 Accelerated Depreciation | Regulatory Assets Currently Earning a Return | SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 180.5 | 168.6
Pirkey Plant Accelerated Depreciation | Regulatory Assets Currently Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 121.4 | 121.3
Pirkey Plant Accelerated Depreciation | Regulatory Assets Currently Earning a Return | SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 121.4 | 121.3
Unrecovered Winter Storm Fuel Costs | Regulatory Assets Currently Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 63.2 | 70.7
Unrecovered Winter Storm Fuel Costs | Regulatory Assets Currently Earning a Return | SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 63.2 | 70.7
Regulatory assets, current |  |  | 37.0 | 37.0
Storm-Related Costs | Regulatory Assets Currently Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 53.5 | 51.0
Storm-Related Costs | Regulatory Assets Currently Earning a Return | AEP Texas |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 41.3 | 41.3
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 339.6 | 300.8
Regulatory asset, recovery of fuel costs, deferred | $ 21.0 | $ 62.0 |  |
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | AEP Texas |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 18.0 | 13.1
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | APCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 161.1 | 144.2
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | I&M |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 6.4 | 6.3
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | PSO |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 7.6 | 4.9
Storm-Related Costs | Regulatory Assets Currently Not Earning a Return | SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 44.7 | 39.9
Plant Retirement Costs – Asset Retirement Obligation Costs | Regulatory Assets Currently Not Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 367.0 | 357.4
Plant Retirement Costs – Asset Retirement Obligation Costs | Regulatory Assets Currently Not Earning a Return | APCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 290.0 | 282.1
Plant Retirement Costs – Asset Retirement Obligation Costs | Regulatory Assets Currently Not Earning a Return | I&M |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 75.1 | 74.0
2024-2025 Virginia Biennial Under-Earnings | Regulatory Assets Currently Not Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 136.8 | 78.4
2024-2025 Virginia Biennial Under-Earnings | Regulatory Assets Currently Not Earning a Return | APCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 136.8 | 78.4
NOLC Costs | Regulatory Assets Currently Not Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 72.0 | 92.8
NOLC Costs | Regulatory Assets Currently Not Earning a Return | I&M |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 0.0 | 26.7
NOLC Costs | Regulatory Assets Currently Not Earning a Return | PSO |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 17.7 | 16.4
NOLC Costs | Regulatory Assets Currently Not Earning a Return | SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 54.2 | 49.6
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 25.1 | 20.7
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Earning a Return | APCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 1.2 | 1.1
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Earning a Return | I&M |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 6.6 | 6.4
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Earning a Return | OPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 0.6 | 0.4
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Earning a Return | SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 17.2 | 10.8
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 100.5 | 86.3
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | AEP Texas |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 1.3 | 1.3
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | APCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 20.6 | 11.9
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | I&M |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 1.6 | 1.6
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | OPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 0.0 | 0.1
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | PSO |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 11.1 | 9.0
Other Regulatory Assets Pending Final Regulatory Approval | Regulatory Assets Currently Not Earning a Return | SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 18.3 | 18.7
Deferred Pension and OPEB Costs | Regulatory Assets Currently Not Earning a Return | AEP Texas |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 18.9 | 15.6
Line Inspection Costs | Regulatory Assets Currently Not Earning a Return | AEP Texas |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 5.8 | 5.8
Pension Settlement | Regulatory Assets Currently Not Earning a Return | APCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | 17.5 | 17.8
Dolet Hills Power Station Accelerated Depreciation | Regulatory Assets Currently Earning a Return | SWEPCo |  |  |  |
Regulatory Asset [Line Items] |  |  |  |
Noncurrent Regulatory Assets |  |  | $ 11.8 | $ 11.8

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