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Benefit Plans 3 (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
American Electric Power System Retirement Savings Plans |  |  |
Cost of Company Matching Contributions | $ 81.9 | $ 79.9 | $ 81.8
Benefit Plans Textuals [Abstract] |  |  |
Matching Contributions Provided Percentage | 100.00% |  |
Eligible Compensation Contribution by Employee Percentage | 1.00% |  |
Second Matching Contributions Provided Percentage | 70.00% |  |
Second Eligible Compensation Contribution by Employee Percentage | 5.00% |  |
Multiemployer Plans Withdrawal Obligation | $ 12.0 | 22.0 |
Noncurrent Regulatory Assets | 4,762.0 | 4,618.8 |
Noncurrent Regulatory Liabilities | 8,115.6 | 8,834.4 |
UMWA Withdrawal Obligation [Member] |  |  |
Benefit Plans Textuals [Abstract] |  |  |
Noncurrent Regulatory Assets | 0.0 | 1.0 |
AEP Texas Inc. [Member] |  |  |
American Electric Power System Retirement Savings Plans |  |  |
Cost of Company Matching Contributions | $ 6.5 | 6.4 | 6.4
Benefit Plans Textuals [Abstract] |  |  |
Matching Contributions Provided Percentage | 100.00% |  |
Eligible Compensation Contribution by Employee Percentage | 1.00% |  |
Second Matching Contributions Provided Percentage | 70.00% |  |
Second Eligible Compensation Contribution by Employee Percentage | 5.00% |  |
Noncurrent Regulatory Assets | $ 298.3 | 275.2 |
Noncurrent Regulatory Liabilities | 1,259.6 | 1,242.0 |
Appalachian Power Co [Member] |  |  |
American Electric Power System Retirement Savings Plans |  |  |
Cost of Company Matching Contributions | $ 7.8 | 7.6 | 7.7
Benefit Plans Textuals [Abstract] |  |  |
Matching Contributions Provided Percentage | 100.00% |  |
Eligible Compensation Contribution by Employee Percentage | 1.00% |  |
Second Matching Contributions Provided Percentage | 70.00% |  |
Second Eligible Compensation Contribution by Employee Percentage | 5.00% |  |
Noncurrent Regulatory Assets | $ 1,058.6 | 757.6 |
Noncurrent Regulatory Liabilities | 1,143.6 | 1,238.8 |
Indiana Michigan Power Co [Member] |  |  |
American Electric Power System Retirement Savings Plans |  |  |
Cost of Company Matching Contributions | $ 11.1 | 10.9 | 11.3
Benefit Plans Textuals [Abstract] |  |  |
Matching Contributions Provided Percentage | 100.00% |  |
Eligible Compensation Contribution by Employee Percentage | 1.00% |  |
Second Matching Contributions Provided Percentage | 70.00% |  |
Second Eligible Compensation Contribution by Employee Percentage | 5.00% |  |
Noncurrent Regulatory Assets | $ 459.6 | 410.9 |
Noncurrent Regulatory Liabilities | 1,702.2 | 2,447.9 |
Ohio Power Co [Member] |  |  |
American Electric Power System Retirement Savings Plans |  |  |
Cost of Company Matching Contributions | $ 7.7 | 7.2 | 7.3
Benefit Plans Textuals [Abstract] |  |  |
Matching Contributions Provided Percentage | 100.00% |  |
Eligible Compensation Contribution by Employee Percentage | 1.00% |  |
Second Matching Contributions Provided Percentage | 70.00% |  |
Second Eligible Compensation Contribution by Employee Percentage | 5.00% |  |
Noncurrent Regulatory Assets | $ 327.3 | 293.0 |
Noncurrent Regulatory Liabilities | 1,044.0 | 1,020.9 |
Public Service Co Of Oklahoma [Member] |  |  |
American Electric Power System Retirement Savings Plans |  |  |
Cost of Company Matching Contributions | $ 4.7 | 4.6 | 4.9
Benefit Plans Textuals [Abstract] |  |  |
Matching Contributions Provided Percentage | 100.00% |  |
Eligible Compensation Contribution by Employee Percentage | 1.00% |  |
Second Matching Contributions Provided Percentage | 70.00% |  |
Second Eligible Compensation Contribution by Employee Percentage | 5.00% |  |
Noncurrent Regulatory Assets | $ 653.7 | 1,037.4 |
Noncurrent Regulatory Liabilities | 809.1 | 835.3 |
Southwestern Electric Power Co [Member] |  |  |
American Electric Power System Retirement Savings Plans |  |  |
Cost of Company Matching Contributions | $ 6.4 | 6.4 | 6.7
Benefit Plans Textuals [Abstract] |  |  |
Matching Contributions Provided Percentage | 100.00% |  |
Eligible Compensation Contribution by Employee Percentage | 1.00% |  |
Second Matching Contributions Provided Percentage | 70.00% |  |
Second Eligible Compensation Contribution by Employee Percentage | 5.00% |  |
Noncurrent Regulatory Assets | $ 1,042.4 | 1,005.3 |
Noncurrent Regulatory Liabilities | 825.7 | 806.9 |
Pension Plans [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 3,883.0 | 4,892.2 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 4,072.7 | 5,187.0 | 5,544.5
Accumulated Benefit Obligation | 3,883.0 | 4,892.2 |
Fair Value of Plan Assets | 4,124.7 | 5,352.9 | 5,556.6
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 6.3 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 123.1 | 129.2 | 111.9
Interest Cost | 148.2 | 137.2 | 167.9
Expected Return on Plan Assets | (253.4) | (229.7) | (264.9)
Amortization of Prior Service Cost (Credit) | 0.0 | 0.0 | 0.0
Amortization of Net Actuarial Loss | 63.0 | 101.5 | 93.7
Settlements | 0.0 | 0.0 | 0.0
Net Periodic Benefit Cost (Credit) | 80.9 | 138.2 | 108.6
Capitalized Portion | (53.8) | (55.7) | (47.0)
Net Periodic Benefit Cost (Credit) Recognized in Expense | 27.1 | 82.5 | 61.6
Pension Plans [Member] | Pension Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 369.0 |  |
2023 | 373.6 |  |
2024 | 368.8 |  |
2025 | 369.6 |  |
2026 | 364.3 |  |
Years 2027 to 2031, in Total | 1,702.3 |  |
Pension Plans [Member] | AEP Texas Inc. [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 317.9 | 394.7 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 334.1 | 419.8 | 453.2
Accumulated Benefit Obligation | 317.9 | 394.7 |
Fair Value of Plan Assets | 335.1 | 444.9 | 474.0
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 0.4 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 11.1 | 11.8 | 10.0
Interest Cost | 12.1 | 11.2 | 13.9
Expected Return on Plan Assets | (21.0) | (19.5) | (22.7)
Amortization of Prior Service Cost (Credit) | 0.0 | 0.0 | 0.0
Amortization of Net Actuarial Loss | 5.2 | 8.3 | 7.8
Net Periodic Benefit Cost (Credit) | 7.4 | 11.8 | 9.0
Capitalized Portion | (6.2) | (6.6) | (5.5)
Net Periodic Benefit Cost (Credit) Recognized in Expense | 1.2 | 5.2 | 3.5
Pension Plans [Member] | AEP Texas Inc. [Member] | Pension Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 35.4 |  |
2023 | 36.3 |  |
2024 | 35.2 |  |
2025 | 35.0 |  |
2026 | 32.6 |  |
Years 2027 to 2031, in Total | 138.9 |  |
Pension Plans [Member] | Appalachian Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 470.4 | 597.4 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 485.7 | 621.7 | 670.8
Accumulated Benefit Obligation | 470.4 | 597.4 |
Fair Value of Plan Assets | 531.7 | 683.3 | 701.3
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 0.0 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 11.4 | 11.9 | 10.5
Interest Cost | 17.5 | 16.4 | 20.3
Expected Return on Plan Assets | (32.3) | (29.1) | (33.6)
Amortization of Prior Service Cost (Credit) | 0.0 | 0.0 | 0.0
Amortization of Net Actuarial Loss | 7.4 | 12.0 | 11.2
Net Periodic Benefit Cost (Credit) | 4.0 | 11.2 | 8.4
Capitalized Portion | (5.0) | (5.2) | (4.5)
Net Periodic Benefit Cost (Credit) Recognized in Expense | (1.0) | 6.0 | 3.9
Pension Plans [Member] | Appalachian Power Co [Member] | Pension Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 43.7 |  |
2023 | 43.6 |  |
2024 | 42.5 |  |
2025 | 43.0 |  |
2026 | 41.8 |  |
Years 2027 to 2031, in Total | 202.1 |  |
Pension Plans [Member] | Indiana Michigan Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 445.0 | 576.4 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 466.8 | 612.1 | 653.3
Accumulated Benefit Obligation | 445.0 | 576.4 |
Fair Value of Plan Assets | 533.7 | 681.5 | 698.1
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 0.1 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 16.2 | 17.5 | 15.4
Interest Cost | 17.0 | 16.2 | 19.7
Expected Return on Plan Assets | (32.4) | (28.9) | (33.3)
Amortization of Prior Service Cost (Credit) | 0.0 | 0.0 | 0.0
Amortization of Net Actuarial Loss | 7.1 | 11.7 | 10.8
Net Periodic Benefit Cost (Credit) | 7.9 | 16.5 | 12.6
Capitalized Portion | (4.6) | (4.9) | (4.3)
Net Periodic Benefit Cost (Credit) Recognized in Expense | 3.3 | 11.6 | 8.3
Pension Plans [Member] | Indiana Michigan Power Co [Member] | Pension Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 38.1 |  |
2023 | 39.8 |  |
2024 | 40.7 |  |
2025 | 40.4 |  |
2026 | 41.0 |  |
Years 2027 to 2031, in Total | 196.4 |  |
Pension Plans [Member] | Ohio Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 344.2 | 440.3 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 363.6 | 470.7 | 510.3
Accumulated Benefit Obligation | 344.2 | 440.3 |
Fair Value of Plan Assets | 406.4 | 524.8 | 543.1
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 11.2 | 11.4 | 9.7
Interest Cost | 13.3 | 12.5 | 15.4
Expected Return on Plan Assets | (24.8) | (22.3) | (26.3)
Amortization of Prior Service Cost (Credit) | 0.0 | 0.0 | 0.0
Amortization of Net Actuarial Loss | 5.5 | 9.1 | 8.5
Net Periodic Benefit Cost (Credit) | 5.2 | 10.7 | 7.3
Capitalized Portion | (6.1) | (6.2) | (5.0)
Net Periodic Benefit Cost (Credit) Recognized in Expense | (0.9) | 4.5 | 2.3
Pension Plans [Member] | Ohio Power Co [Member] | Pension Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 32.3 |  |
2023 | 31.9 |  |
2024 | 32.4 |  |
2025 | 32.0 |  |
2026 | 31.6 |  |
Years 2027 to 2031, in Total | 146.0 |  |
Pension Plans [Member] | Public Service Co Of Oklahoma [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 180.3 | 233.6 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 192.3 | 252.6 | 279.9
Accumulated Benefit Obligation | 180.3 | 233.6 |
Fair Value of Plan Assets | 218.5 | 286.2 | 299.8
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 0.1 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 7.4 | 8.0 | 7.3
Interest Cost | 7.0 | 6.7 | 8.5
Expected Return on Plan Assets | (13.4) | (12.3) | (14.5)
Amortization of Prior Service Cost (Credit) | 0.0 | 0.0 | 0.0
Amortization of Net Actuarial Loss | 2.9 | 4.9 | 4.7
Net Periodic Benefit Cost (Credit) | 3.9 | 7.3 | 6.0
Capitalized Portion | (3.2) | (3.4) | (2.8)
Net Periodic Benefit Cost (Credit) Recognized in Expense | 0.7 | 3.9 | 3.2
Pension Plans [Member] | Public Service Co Of Oklahoma [Member] | Pension Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 19.2 |  |
2023 | 18.9 |  |
2024 | 19.0 |  |
2025 | 19.2 |  |
2026 | 18.4 |  |
Years 2027 to 2031, in Total | 81.1 |  |
Pension Plans [Member] | Southwestern Electric Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 235.1 | 292.7 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 250.7 | 317.7 | 334.5
Accumulated Benefit Obligation | 235.1 | 292.7 |
Fair Value of Plan Assets | 231.3 | 308.3 | 326.9
Underfunded Status, Projected Benefit Obligation | (19.4) | (9.4) |
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 0.1 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 10.6 | 11.2 | 9.9
Interest Cost | 9.1 | 8.5 | 10.2
Expected Return on Plan Assets | (14.6) | (13.5) | (15.7)
Amortization of Prior Service Cost (Credit) | 0.0 | 0.0 | 0.0
Amortization of Net Actuarial Loss | 3.8 | 6.2 | 5.7
Net Periodic Benefit Cost (Credit) | 8.9 | 12.4 | 10.1
Capitalized Portion | (4.0) | (4.1) | (3.4)
Net Periodic Benefit Cost (Credit) Recognized in Expense | 4.9 | 8.3 | 6.7
Pension Plans [Member] | Southwestern Electric Power Co [Member] | Pension Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 24.2 |  |
2023 | 25.1 |  |
2024 | 25.3 |  |
2025 | 25.5 |  |
2026 | 25.4 |  |
Years 2027 to 2031, in Total | 107.9 |  |
Qualified Pension Plans [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 3,827.4 | 4,822.5 |
Underfunded Benefit Obligation |  |  |
Accumulated Benefit Obligation | 3,827.4 | 4,822.5 |
Qualified Pension Plans [Member] | AEP Texas Inc. [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 315.4 | 391.4 |
Underfunded Benefit Obligation |  |  |
Accumulated Benefit Obligation | 315.4 | 391.4 |
Qualified Pension Plans [Member] | Appalachian Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 470.1 | 597.0 |
Underfunded Benefit Obligation |  |  |
Accumulated Benefit Obligation | 470.1 | 597.0 |
Qualified Pension Plans [Member] | Indiana Michigan Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 443.8 | 575.2 |
Underfunded Benefit Obligation |  |  |
Accumulated Benefit Obligation | 443.8 | 575.2 |
Qualified Pension Plans [Member] | Ohio Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 344.1 | 440.0 |
Underfunded Benefit Obligation |  |  |
Accumulated Benefit Obligation | 344.1 | 440.0 |
Qualified Pension Plans [Member] | Public Service Co Of Oklahoma [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 179.1 | 232.1 |
Underfunded Benefit Obligation |  |  |
Accumulated Benefit Obligation | 179.1 | 232.1 |
Qualified Pension Plans [Member] | Southwestern Electric Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 234.0 | 291.4 |
Underfunded Benefit Obligation |  |  |
Accumulated Benefit Obligation | 234.0 | 291.4 |
Nonqualified Pension Plans [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 55.6 | 69.7 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 61.5 | 78.4 |
Accumulated Benefit Obligation | 55.6 | 69.7 |
Fair Value of Plan Assets | 0.0 | 0.0 |
Underfunded Status, Projected Benefit Obligation | (61.5) | (78.4) |
Underfunded Status, Accumulated Benefit Obligation | (55.6) | (69.7) |
Nonqualified Pension Plans [Member] | AEP Texas Inc. [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 2.5 | 3.3 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 2.7 | 3.6 |
Accumulated Benefit Obligation | 2.5 | 3.3 |
Fair Value of Plan Assets | 0.0 | 0.0 |
Underfunded Status, Projected Benefit Obligation | (2.7) | (3.6) |
Underfunded Status, Accumulated Benefit Obligation | (2.5) | (3.3) |
Nonqualified Pension Plans [Member] | Appalachian Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 0.3 | 0.4 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 0.6 | 0.8 |
Accumulated Benefit Obligation | 0.3 | 0.4 |
Fair Value of Plan Assets | 0.0 | 0.0 |
Underfunded Status, Projected Benefit Obligation | (0.6) | (0.8) |
Underfunded Status, Accumulated Benefit Obligation | (0.3) | (0.4) |
Nonqualified Pension Plans [Member] | Indiana Michigan Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 1.2 | 1.2 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 1.6 | 1.9 |
Accumulated Benefit Obligation | 1.2 | 1.2 |
Fair Value of Plan Assets | 0.0 | 0.0 |
Underfunded Status, Projected Benefit Obligation | (1.6) | (1.9) |
Underfunded Status, Accumulated Benefit Obligation | (1.2) | (1.2) |
Nonqualified Pension Plans [Member] | Ohio Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 0.1 | 0.3 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 0.3 | 0.7 |
Accumulated Benefit Obligation | 0.1 | 0.3 |
Fair Value of Plan Assets | 0.0 | 0.0 |
Underfunded Status, Projected Benefit Obligation | (0.3) | (0.7) |
Underfunded Status, Accumulated Benefit Obligation | (0.1) | (0.3) |
Nonqualified Pension Plans [Member] | Public Service Co Of Oklahoma [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 1.2 | 1.5 |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 1.5 | 1.9 |
Accumulated Benefit Obligation | 1.2 | 1.5 |
Fair Value of Plan Assets | 0.0 | 0.0 |
Underfunded Status, Projected Benefit Obligation | (1.5) | (1.9) |
Underfunded Status, Accumulated Benefit Obligation | (1.2) | (1.5) |
Nonqualified Pension Plans [Member] | Southwestern Electric Power Co [Member] |  |  |
Accumulated Benefit Obligation |  |  |
Accumulated Benefit Obligation | 1.1 | 1.3 |
Underfunded Benefit Obligation |  |  |
Accumulated Benefit Obligation | 1.1 | 1.3 |
Fair Value of Plan Assets | 231.3 | 0.0 |
Underfunded Status, Accumulated Benefit Obligation | (3.8) | (1.3) |
Other Postretirement Benefit Plans [Member] |  |  |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 872.6 | 1,041.3 | 1,210.9
Fair Value of Plan Assets | 1,549.3 | 2,044.3 | 1,946.7
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 3.1 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 7.4 | 9.5 | 10.0
Interest Cost | 29.2 | 30.5 | 39.8
Expected Return on Plan Assets | (110.0) | (91.1) | (95.6)
Amortization of Prior Service Cost (Credit) | (71.4) | (70.9) | (69.8)
Amortization of Net Actuarial Loss | 0.0 | 0.0 | 5.9
Settlements | 0.0 | 0.0 | 0.0
Net Periodic Benefit Cost (Credit) | (144.8) | (122.0) | (109.7)
Capitalized Portion | (3.2) | (4.1) | (4.2)
Net Periodic Benefit Cost (Credit) Recognized in Expense | (148.0) | (126.1) | (113.9)
Other Postretirement Benefit Plans [Member] | Benefit Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 116.0 |  |
2023 | 117.6 |  |
2024 | 126.9 |  |
2025 | 127.4 |  |
2026 | 126.8 |  |
Years 2027 to 2031, in Total | 604.0 |  |
Other Postretirement Benefit Plans [Member] | Medicare Subsidy Receipts [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 0.2 |  |
2023 | 0.3 |  |
2024 | 0.3 |  |
2025 | 0.3 |  |
2026 | 0.3 |  |
Years 2027 to 2031, in Total | 1.6 |  |
Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] |  |  |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 68.6 | 80.5 | 96.3
Fair Value of Plan Assets | 128.3 | 168.8 | 162.3
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 0.1 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 0.5 | 0.7 | 0.8
Interest Cost | 2.2 | 2.4 | 3.2
Expected Return on Plan Assets | (9.1) | (7.5) | (8.0)
Amortization of Prior Service Cost (Credit) | (6.1) | (6.0) | (5.9)
Amortization of Net Actuarial Loss | 0.0 | 0.0 | 0.5
Net Periodic Benefit Cost (Credit) | (12.5) | (10.4) | (9.4)
Capitalized Portion | (0.3) | (0.4) | (0.4)
Net Periodic Benefit Cost (Credit) Recognized in Expense | (12.8) | (10.8) | (9.8)
Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] | Benefit Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 9.1 |  |
2023 | 9.5 |  |
2024 | 10.4 |  |
2025 | 10.6 |  |
2026 | 10.6 |  |
Years 2027 to 2031, in Total | 48.5 |  |
Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] | Medicare Subsidy Receipts [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 0.0 |  |
2023 | 0.0 |  |
2024 | 0.0 |  |
2025 | 0.0 |  |
2026 | 0.0 |  |
Years 2027 to 2031, in Total | 0.0 |  |
Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] |  |  |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 140.7 | 167.3 | 198.2
Fair Value of Plan Assets | 228.6 | 302.3 | 293.0
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 1.6 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 0.8 | 1.0 | 1.0
Interest Cost | 4.7 | 4.9 | 6.6
Expected Return on Plan Assets | (16.3) | (13.5) | (14.4)
Amortization of Prior Service Cost (Credit) | (10.4) | (10.3) | (10.2)
Amortization of Net Actuarial Loss | 0.0 | 0.0 | 0.9
Net Periodic Benefit Cost (Credit) | (21.2) | (17.9) | (16.1)
Capitalized Portion | (0.4) | (0.4) | (0.4)
Net Periodic Benefit Cost (Credit) Recognized in Expense | (21.6) | (18.3) | (16.5)
Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] | Benefit Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 19.0 |  |
2023 | 19.3 |  |
2024 | 20.5 |  |
2025 | 20.4 |  |
2026 | 20.3 |  |
Years 2027 to 2031, in Total | 95.8 |  |
Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] | Medicare Subsidy Receipts [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 0.1 |  |
2023 | 0.1 |  |
2024 | 0.1 |  |
2025 | 0.1 |  |
2026 | 0.1 |  |
Years 2027 to 2031, in Total | 0.5 |  |
Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] |  |  |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 101.9 | 118.6 | 141.4
Fair Value of Plan Assets | 190.5 | 248.7 | 238.2
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 0.0 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 0.9 | 1.3 | 1.4
Interest Cost | 3.4 | 3.5 | 4.7
Expected Return on Plan Assets | (13.7) | (11.1) | (11.7)
Amortization of Prior Service Cost (Credit) | (9.7) | (9.6) | (9.5)
Amortization of Net Actuarial Loss | 0.0 | 0.0 | 0.7
Net Periodic Benefit Cost (Credit) | (19.1) | (15.9) | (14.4)
Capitalized Portion | (0.3) | (0.4) | (0.4)
Net Periodic Benefit Cost (Credit) Recognized in Expense | (19.4) | (16.3) | (14.8)
Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] | Benefit Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 14.9 |  |
2023 | 15.0 |  |
2024 | 16.1 |  |
2025 | 16.3 |  |
2026 | 16.1 |  |
Years 2027 to 2031, in Total | 75.1 |  |
Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] | Medicare Subsidy Receipts [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 0.0 |  |
2023 | 0.0 |  |
2024 | 0.0 |  |
2025 | 0.0 |  |
2026 | 0.0 |  |
Years 2027 to 2031, in Total | 0.0 |  |
Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member] |  |  |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 88.9 | 104.9 | 126.4
Fair Value of Plan Assets | 166.2 | 220.0 | 213.0
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 0.6 | 0.8 | 0.9
Interest Cost | 3.0 | 3.0 | 4.2
Expected Return on Plan Assets | (12.0) | (9.7) | (10.5)
Amortization of Prior Service Cost (Credit) | (7.1) | (7.2) | (7.0)
Amortization of Net Actuarial Loss | 0.0 | 0.0 | 0.7
Net Periodic Benefit Cost (Credit) | (15.5) | (13.1) | (11.7)
Capitalized Portion | (0.3) | (0.4) | (0.5)
Net Periodic Benefit Cost (Credit) Recognized in Expense | (15.8) | (13.5) | (12.2)
Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member] | Benefit Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 12.6 |  |
2023 | 12.6 |  |
2024 | 13.5 |  |
2025 | 13.4 |  |
2026 | 13.3 |  |
Years 2027 to 2031, in Total | 62.3 |  |
Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member] | Medicare Subsidy Receipts [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 0.0 |  |
2023 | 0.0 |  |
2024 | 0.0 |  |
2025 | 0.0 |  |
2026 | 0.0 |  |
Years 2027 to 2031, in Total | 0.0 |  |
Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member] |  |  |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 45.7 | 54.4 | 64.0
Fair Value of Plan Assets | 85.4 | 114.0 | 107.8
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 0.0 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 0.4 | 0.6 | 0.7
Interest Cost | 1.5 | 1.6 | 2.1
Expected Return on Plan Assets | (6.1) | (5.0) | (5.2)
Amortization of Prior Service Cost (Credit) | (4.4) | (4.4) | (4.4)
Amortization of Net Actuarial Loss | 0.0 | 0.0 | 0.3
Net Periodic Benefit Cost (Credit) | (8.6) | (7.2) | (6.5)
Capitalized Portion | (0.2) | (0.3) | (0.3)
Net Periodic Benefit Cost (Credit) Recognized in Expense | (8.8) | (7.5) | (6.8)
Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member] | Benefit Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 6.7 |  |
2023 | 6.9 |  |
2024 | 7.4 |  |
2025 | 7.3 |  |
2026 | 7.1 |  |
Years 2027 to 2031, in Total | 32.2 |  |
Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member] | Medicare Subsidy Receipts [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 0.0 |  |
2023 | 0.0 |  |
2024 | 0.0 |  |
2025 | 0.0 |  |
2026 | 0.0 |  |
Years 2027 to 2031, in Total | 0.0 |  |
Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] |  |  |
Underfunded Benefit Obligation |  |  |
Projected Benefit Obligation | 55.1 | 65.2 | 77.1
Fair Value of Plan Assets | 103.0 | 136.6 | 129.9
Estimated Future Benefit Payments and Contributions |  |  |
Expected Contributions and Payments During 2022 | 0.0 |  |
Components of Net Periodic Benefit Cost |  |  |
Service Cost | 0.6 | 0.8 | 0.8
Interest Cost | 1.8 | 1.9 | 2.5
Expected Return on Plan Assets | (7.3) | (6.1) | (6.3)
Amortization of Prior Service Cost (Credit) | (5.3) | (5.3) | (5.2)
Amortization of Net Actuarial Loss | 0.0 | 0.0 | 0.4
Net Periodic Benefit Cost (Credit) | (10.2) | (8.7) | (7.8)
Capitalized Portion | (0.2) | (0.3) | (0.3)
Net Periodic Benefit Cost (Credit) Recognized in Expense | (10.4) | $ (9.0) | $ (8.1)
Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] | Benefit Payments [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 7.5 |  |
2023 | 7.8 |  |
2024 | 8.5 |  |
2025 | 8.6 |  |
2026 | 8.5 |  |
Years 2027 to 2031, in Total | 41.2 |  |
Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] | Medicare Subsidy Receipts [Member] |  |  |
Estimated Future Benefit Payments and Contributions |  |  |
2022 | 0.0 |  |
2023 | 0.0 |  |
2024 | 0.0 |  |
2025 | 0.0 |  |
2026 | 0.0 |  |
Years 2027 to 2031, in Total | $ 0.0 |  |

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