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Income Taxes (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Federal:      
Current $ 113.1 $ (27.8) $ (138.2)
Deferred (88.8) 182.6 146.9
Total Federal 24.3 154.8 8.7
Current 26.6 6.0 (16.7)
Deferred (45.5) (45.3) 48.5
Total State and Local (18.9) (39.3) 31.8
Income Tax Expense (Benefit):      
Income Tax Expense/Benefit 5.4 115.5 40.5
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Net Income 2,305.6 2,488.1 2,196.7
Less: Equity Earnings 109.4 (91.7) (91.1)
Income Tax Expense/Benefit 5.4 115.5 40.5
Pretax Income 2,309.6 2,600.2 2,234.3
Income Taxes on Pretax Income at Statutory Rate (21%) $ 485.0 $ 546.0 $ 469.2
Federal Statutory Income Tax Rate 21.00% 21.00% 21.00%
Reconciliation of Federal Statutory Rate and Amount of Taxes Reported      
Depreciation $ 17.1 $ 25.9 $ 26.5
Income Tax Reconciliation Nondeductible Expense Permanent Miscellaneous 11.5 (1.3) (9.7)
Investment Tax Credit Amortization (14.3) (22.0) (18.8)
Production Tax Credits (197.1) (98.8) (83.1)
State and Local Income Taxes, Net (14.0) 39.4 25.1
Removal Costs (26.5) (20.0) (18.6)
AFUDC (29.3) (30.6) (32.5)
Increase Decrease in Income Taxes Due to Tax Reserve Adjustments 0.0 (55.1) [1] 0.0
Tax Reform Excess ADIT Reversal (214.5) (255.6) (268.2)
Federal Return to Provision (17.4) (1.6) (2.6)
CARES Act Provision 0.0 0.0 (48.0)
Other 4.9 (10.8) 1.2
Income Tax Expense/Benefit $ 5.4 $ 115.5 $ 40.5
Effective Income Tax Rate 0.20% 4.40% 1.80%
Net Deferred Tax Liability and Significant Temporary Differences      
Deferred Tax Assets $ 3,567.4 $ 3,347.1  
Deferred Tax Liabilities (12,464.3) (11,991.2)  
Property Related Temporary Differences (7,788.1) (7,346.4)  
Amounts Due from Customers for Future Federal Income Taxes 962.7 1,086.6  
Deferred State Income Taxes (1,049.3) (1,211.8)  
Securitized Assets (98.9) (128.8)  
Regulatory Assets (865.2) (746.6)  
Accrued Nuclear Decommissioning (632.7) (743.2)  
Net Operating Loss Carryforward 132.4 303.2  
Deferred Tax Assets, Tax Credit Carryforwards [Abstract]      
Tax Credit Carryforward 612.0 440.1  
Operating Lease Liability 142.9 116.3  
Investment in Partnership (338.9) (392.1)  
All Other, Net 44.8 41.0  
Net Deferred Tax Liabilities (8,896.9) (8,644.1)  
Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits      
Balance at January 1, 14.3 13.2 $ 24.1
Increase - Tax Positions Taken During a Prior Period 5.1 1.2 0.6
Decrease - Tax Positions Taken During a Prior Period 0.0 (3.2) (14.5)
Increase - Tax Positions Taken During the Current Year 3.8 3.1 3.0
Decrease - Settlements with Taxing Authorities 0.0 0.0 0.0
Decrease - Lapse of the Applicable Statute of Limitations 0.0 0.0 0.0
Balance at December 31, 23.2 14.3 13.2
Tax Contingency [Abstract]      
Unrecognized Tax Benefits, if Recognized - Amount 23.0 14.0 12.0
Income Taxes (Textuals) [Abstract]      
Valuation Allowance (28.2) (25.0)  
Income Tax Expense/Benefit 5.4 115.5 40.5
Income Taxes Receivable   95.0  
Income Tax Expense Re-Measurement   23.0  
Operating Income (Loss) (3,482.7) (3,411.3) (2,987.7)
Deferred Revenue 7.1 8.8  
Liability, Retirement and Postemployment Benefits 2.5 (46.2)  
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]      
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions 5.1 1.2 0.6
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions 0.0 3.2 14.5
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions 3.8 3.1 3.0
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions 0.0 0.0 0.0
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities 0.0 0.0 0.0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations 0.0 0.0 0.0
Unrecognized Tax Benefits $ 23.2 14.3 13.2
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability     48.0
Minimum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2036    
Maximum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2041    
AEP Texas Inc. [Member]      
Federal:      
Current $ 29.0 (1.2) 5.2
Deferred 41.4 40.5 (15.4)
Total Federal 70.4 39.3 (10.2)
Current 2.2 3.0 (0.1)
Deferred 0.0 0.8 (0.9)
Total State and Local 2.2 3.8 (1.0)
Income Tax Expense (Benefit):      
Income Tax Expense/Benefit 72.6 43.1 (11.2)
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Net Income 307.9 289.8 241.0
Income Tax Expense/Benefit 72.6 43.1 (11.2)
Pretax Income 380.5 332.9 229.8
Income Taxes on Pretax Income at Statutory Rate (21%) $ 79.9 $ 69.9 $ 48.3
Federal Statutory Income Tax Rate 21.00% 21.00% 21.00%
Reconciliation of Federal Statutory Rate and Amount of Taxes Reported      
State and Local Income Taxes, Net $ 1.7 $ 2.4 $ (0.8)
AFUDC (4.1) (4.5) (4.1)
Parent Company Loss Benefit 0.0 (3.2) (4.5)
Tax Reform Excess ADIT Reversal (5.5) (21.3) (47.9)
Other 0.6 (0.2) (2.2)
Income Tax Expense/Benefit $ 72.6 $ 43.1 $ (11.2)
Effective Income Tax Rate 19.10% 12.90% (4.90%)
Net Deferred Tax Liability and Significant Temporary Differences      
Deferred Tax Assets $ 177.0 $ 173.8  
Deferred Tax Liabilities (1,321.2) (1,262.7)  
Property Related Temporary Differences (1,130.7) (1,060.2)  
Amounts Due from Customers for Future Federal Income Taxes 111.0 110.0  
Deferred State Income Taxes (36.6) (32.2)  
Securitized Transition Assets (65.0) (84.4)  
Regulatory Assets (48.9) (45.1)  
Deferred Tax Assets, Tax Credit Carryforwards [Abstract]      
Operating Lease Liability 20.3 15.8  
All Other, Net 5.7 7.2  
Net Deferred Tax Liabilities (1,144.2) (1,088.9)  
Income Taxes (Textuals) [Abstract]      
Income Tax Expense/Benefit 72.6 43.1 $ (11.2)
Operating Income (Loss) $ (549.2) (476.0) (369.6)
AEP Texas Inc. [Member] | Minimum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2036    
AEP Texas Inc. [Member] | Maximum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2041    
AEP Transmission Co [Member]      
Federal:      
Current $ 98.0 69.8 22.2
Deferred 46.0 54.1 65.4
Total Federal 144.0 123.9 87.6
Current 8.8 5.8 2.8
Deferred 16.3 14.4 16.3
Total State and Local 25.1 20.2 19.1
Income Tax Expense (Benefit):      
Income Tax Expense/Benefit 169.1 144.1 106.7
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Net Income 594.2 591.7 423.4
Income Tax Expense/Benefit 169.1 144.1 106.7
Pretax Income 763.3 735.8 530.1
Income Taxes on Pretax Income at Statutory Rate (21%) $ 160.3 $ 154.5 $ 111.3
Federal Statutory Income Tax Rate 21.00% 21.00% 21.00%
Reconciliation of Federal Statutory Rate and Amount of Taxes Reported      
State and Local Income Taxes, Net $ 19.8 $ 19.8 $ 15.1
AFUDC (14.8) (14.1) (15.5)
Parent Company Loss Benefit 0.0 (18.3) (7.0)
Other 3.8 2.2 2.8
Income Tax Expense/Benefit $ 169.1 $ 144.1 $ 106.7
Effective Income Tax Rate 22.20% 19.60% 20.10%
Net Deferred Tax Liability and Significant Temporary Differences      
Deferred Tax Assets $ 165.0 $ 161.2  
Deferred Tax Liabilities (1,221.5) (1,139.5)  
Property Related Temporary Differences (1,081.5) (1,012.4)  
Amounts Due from Customers for Future Federal Income Taxes 118.5 120.1  
Deferred State Income Taxes (108.1) (97.0)  
Regulatory Assets (1.1) (1.3)  
Net Operating Loss Carryforward 5.5 8.1  
Deferred Tax Assets, Tax Credit Carryforwards [Abstract]      
Tax Credit Carryforward 0.2 0.1  
Operating Lease Liability 0.3 0.1  
Investment in Partnership (0.1) (0.1)  
All Other, Net 9.8 4.1  
Net Deferred Tax Liabilities (1,056.5) (978.3)  
Income Taxes (Textuals) [Abstract]      
Income Tax Expense/Benefit 169.1 144.1 $ 106.7
Operating Income (Loss) $ (853.7) (809.3) (581.5)
AEP Transmission Co [Member] | Minimum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2036    
AEP Transmission Co [Member] | Maximum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2041    
Appalachian Power Co [Member]      
Federal:      
Current $ (61.0) 5.0 21.4
Deferred 86.6 14.9 (27.1)
Total Federal 25.6 19.9 (5.7)
Current (0.4) 2.2 9.3
Deferred (7.0) 0.0 0.7
Total State and Local (7.4) 2.2 10.0
Income Tax Expense (Benefit):      
Income Tax Expense/Benefit 18.2 22.1 4.3
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Net Income 394.2 348.9 369.7
Income Tax Expense/Benefit 18.2 22.1 4.3
Pretax Income 412.4 371.0 374.0
Income Taxes on Pretax Income at Statutory Rate (21%) $ 86.6 $ 77.9 $ 78.5
Federal Statutory Income Tax Rate 21.00% 21.00% 21.00%
Reconciliation of Federal Statutory Rate and Amount of Taxes Reported      
Depreciation $ 4.7 $ 11.7 $ 12.7
State and Local Income Taxes, Net (5.9) 2.1 7.9
Removal Costs (9.8) (7.3) (5.7)
AFUDC (3.7) (4.6) (4.5)
Parent Company Loss Benefit 0.0 0.0 (6.2)
Increase Decrease in Income Taxes Due to Tax Reserve Adjustments 0.0 4.5 [1] 0.0
Tax Reform Excess ADIT Reversal (50.9) (60.5) (72.3)
Federal Return to Provision (2.8) (1.6) (7.2)
Other 0.0 (0.1) 1.1
Income Tax Expense/Benefit $ 18.2 $ 22.1 $ 4.3
Effective Income Tax Rate 4.40% 6.00% 1.10%
Net Deferred Tax Liability and Significant Temporary Differences      
Deferred Tax Assets $ 510.3 $ 495.1  
Deferred Tax Liabilities (2,502.5) (2,299.8)  
Property Related Temporary Differences (1,509.8) (1,476.5)  
Amounts Due from Customers for Future Federal Income Taxes 163.0 182.1  
Deferred State Income Taxes (318.5) (288.8)  
Securitized Assets (33.9) (39.3)  
Regulatory Assets (301.2) (177.0)  
Deferred Tax Assets, Tax Credit Carryforwards [Abstract]      
Operating Lease Liability 15.6 14.2  
All Other, Net (7.4) (19.4)  
Net Deferred Tax Liabilities (1,992.2) (1,804.7)  
Income Taxes (Textuals) [Abstract]      
Income Tax Expense/Benefit 18.2 22.1 $ 4.3
Operating Income (Loss) $ (602.1) (549.4) (556.6)
Appalachian Power Co [Member] | Minimum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2036    
Appalachian Power Co [Member] | Maximum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2041    
Indiana Michigan Power Co [Member]      
Federal:      
Current $ 43.4 26.9 11.3
Deferred (51.3) (35.5) (20.6)
Total Federal (7.9) (8.6) (9.3)
Current 10.9 (0.6) 1.9
Deferred 1.2 (1.4) (0.1)
Total State and Local 12.1 (2.0) 1.8
Income Tax Expense (Benefit):      
Income Tax Expense/Benefit 4.2 (10.6) (7.5)
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Net Income 324.7 279.8 284.8
Income Tax Expense/Benefit 4.2 (10.6) (7.5)
Pretax Income 328.9 269.2 277.3
Income Taxes on Pretax Income at Statutory Rate (21%) $ 69.1 $ 56.5 $ 58.2
Federal Statutory Income Tax Rate 21.00% 21.00% 21.00%
Reconciliation of Federal Statutory Rate and Amount of Taxes Reported      
Depreciation $ 2.9 $ 3.5 $ 1.6
Investment Tax Credit Amortization (3.1) (6.4) (4.5)
State and Local Income Taxes, Net 9.6 (1.3) 1.5
Removal Costs (12.4) (9.7) (10.5)
AFUDC (2.1) (2.7) (2.4)
Parent Company Loss Benefit 0.0 (2.8) (6.4)
Tax Reform Excess ADIT Reversal (54.0) (46.3) (46.8)
Federal Return to Provision (6.2) (0.6) 1.8
Other 0.4 (0.8) 0.0
Income Tax Expense/Benefit $ 4.2 $ (10.6) $ (7.5)
Effective Income Tax Rate 1.30% (3.90%) (2.70%)
Net Deferred Tax Liability and Significant Temporary Differences      
Deferred Tax Assets $ 933.7 $ 1,072.2  
Deferred Tax Liabilities (2,090.7) (2,172.4)  
Property Related Temporary Differences (398.0) (286.2)  
Amounts Due from Customers for Future Federal Income Taxes 114.3 135.5  
Deferred State Income Taxes (227.0) (222.0)  
Regulatory Assets (29.5) (23.6)  
Accrued Nuclear Decommissioning (632.7) (743.2)  
Deferred Tax Assets, Tax Credit Carryforwards [Abstract]      
Operating Lease Liability 13.6 13.5  
All Other, Net 2.3 25.8  
Net Deferred Tax Liabilities (1,157.0) (1,100.2)  
Income Taxes (Textuals) [Abstract]      
Income Tax Expense/Benefit 4.2 (10.6) $ (7.5)
Operating Income (Loss) $ (419.9) (357.9) (362.9)
Indiana Michigan Power Co [Member] | Minimum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2036    
Indiana Michigan Power Co [Member] | Maximum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2041    
Ohio Power Co [Member]      
Federal:      
Current $ (27.0) 6.8 (26.6)
Deferred 73.3 25.2 74.0
Total Federal 46.3 32.0 47.4
Current (0.3) (3.1) (5.4)
Deferred (1.8) 5.5 3.2
Total State and Local (2.1) 2.4 (2.2)
Income Tax Expense (Benefit):      
Income Tax Expense/Benefit 44.2 34.4 45.2
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Net Income 287.8 253.6 271.4
Less: Equity Earnings (0.6) 0.0 0.0
Income Tax Expense/Benefit 44.2 34.4 45.2
Pretax Income 331.4 288.0 316.6
Income Taxes on Pretax Income at Statutory Rate (21%) $ 69.6 $ 60.5 $ 66.5
Federal Statutory Income Tax Rate 21.00% 21.00% 21.00%
Reconciliation of Federal Statutory Rate and Amount of Taxes Reported      
Depreciation $ 3.0 $ 2.2 $ 3.7
State and Local Income Taxes, Net (1.6) 0.0 (1.7)
AFUDC (2.9) (2.3) (2.6)
Increase Decrease in Income Taxes Due to Tax Reserve Adjustments 0.0 8.9 [1] 0.0
Tax Reform Excess ADIT Reversal (27.5) (32.6) (27.2)
Federal Return to Provision 3.5 (1.2) 6.5
Other 0.1 (1.1) 0.0
Income Tax Expense/Benefit $ 44.2 $ 34.4 $ 45.2
Effective Income Tax Rate 13.30% 11.90% 14.30%
Net Deferred Tax Liability and Significant Temporary Differences      
Deferred Tax Assets $ 218.8 $ 204.4  
Deferred Tax Liabilities (1,319.9) (1,205.3)  
Property Related Temporary Differences (1,133.8) (1,042.0)  
Amounts Due from Customers for Future Federal Income Taxes 112.6 117.7  
Deferred State Income Taxes (59.6) (58.8)  
Regulatory Assets (57.6) (39.8)  
Deferred Tax Assets, Tax Credit Carryforwards [Abstract]      
Operating Lease Liability 15.5 17.2  
All Other, Net 21.8 4.8  
Net Deferred Tax Liabilities (1,101.1) (1,000.9)  
Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits      
Balance at January 1, 0.0 3.2 $ 8.4
Increase - Tax Positions Taken During a Prior Period 5.1 0.0 0.0
Decrease - Tax Positions Taken During a Prior Period 0.0 (3.2) (5.2)
Increase - Tax Positions Taken During the Current Year 0.0 0.0 0.0
Decrease - Settlements with Taxing Authorities 0.0 0.0 0.0
Decrease - Lapse of the Applicable Statute of Limitations 0.0 0.0 0.0
Balance at December 31, 5.1 0.0 3.2
Income Taxes (Textuals) [Abstract]      
Income Tax Expense/Benefit 44.2 34.4 45.2
Operating Income (Loss) (413.7) (385.2) (403.7)
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]      
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions 5.1 0.0 0.0
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions 0.0 3.2 5.2
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions 0.0 0.0 0.0
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions 0.0 0.0 0.0
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities 0.0 0.0 0.0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations 0.0 0.0 0.0
Unrecognized Tax Benefits $ 5.1 0.0 3.2
Ohio Power Co [Member] | Minimum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2036    
Ohio Power Co [Member] | Maximum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2041    
Public Service Co Of Oklahoma [Member]      
Federal:      
Current $ (3.3) (109.6) (11.4)
Deferred (50.5) 105.6 8.3
Total Federal (53.8) (4.0) (3.1)
Current 0.0 0.0 0.1
Deferred 4.6 8.1 8.2
Total State and Local 4.6 8.1 8.3
Income Tax Expense (Benefit):      
Income Tax Expense/Benefit (49.2) 4.1 5.2
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Net Income 167.6 141.1 123.0
Income Tax Expense/Benefit (49.2) 4.1 5.2
Pretax Income 118.4 145.2 128.2
Income Taxes on Pretax Income at Statutory Rate (21%) $ 24.9 $ 30.5 $ 26.9
Federal Statutory Income Tax Rate 21.00% 21.00% 21.00%
Reconciliation of Federal Statutory Rate and Amount of Taxes Reported      
Investment Tax Credit Amortization $ (1.6) $ (1.8) $ (2.1)
Production Tax Credits (47.7) (6.0) 0.0
State and Local Income Taxes, Net 4.3 6.4 6.5
Parent Company Loss Benefit 0.0 0.0 (0.2)
Tax Reform Excess ADIT Reversal (25.4) (25.4) (25.5)
Federal Return to Provision (3.7) 0.7 (0.5)
Other 0.0 (0.3) 0.1
Income Tax Expense/Benefit $ (49.2) $ 4.1 $ 5.2
Effective Income Tax Rate (41.60%) 2.80% 4.10%
Net Deferred Tax Liability and Significant Temporary Differences      
Deferred Tax Assets $ 225.0 $ 170.0  
Deferred Tax Liabilities (1,013.6) (952.3)  
Property Related Temporary Differences (763.3) (708.6)  
Amounts Due from Customers for Future Federal Income Taxes 96.0 111.5  
Deferred State Income Taxes (81.9) (83.2)  
Regulatory Assets (140.2) (228.0)  
Net Operating Loss Carryforward 25.8 111.4  
Deferred Tax Assets, Tax Credit Carryforwards [Abstract]      
Tax Credit Carryforward 54.3 6.6  
All Other, Net 20.7 8.0  
Net Deferred Tax Liabilities (788.6) (782.3)  
Income Taxes (Textuals) [Abstract]      
Income Tax Expense/Benefit (49.2) 4.1 $ 5.2
Operating Income (Loss) $ (180.8) (192.9) (175.9)
Public Service Co Of Oklahoma [Member] | Minimum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2036    
Public Service Co Of Oklahoma [Member] | Maximum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2041    
Southwestern Electric Power Co [Member]      
Federal:      
Current $ (32.3) (16.7) (13.6)
Deferred 13.4 26.2 19.6
Total Federal (18.9) 9.5 6.0
Current (1.8) 0.4 (8.2)
Deferred (4.5) (10.5) 11.6
Total State and Local (6.3) (10.1) 3.4
Income Tax Expense (Benefit):      
Income Tax Expense/Benefit (25.2) (0.6) 9.4
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Net Income 294.3 242.1 183.7
Less: Equity Earnings (1.4) (3.4) (2.9)
Income Tax Expense/Benefit (25.2) (0.6) 9.4
Pretax Income 267.7 238.1 190.2
Income Taxes on Pretax Income at Statutory Rate (21%) $ 56.2 $ 50.0 $ 39.9
Federal Statutory Income Tax Rate 21.00% 21.00% 21.00%
Reconciliation of Federal Statutory Rate and Amount of Taxes Reported      
Depreciation $ 2.3 $ 1.8 $ 1.9
Depletion (4.0) (2.7) (3.4)
Production Tax Credits (57.1) (7.2) 0.0
State and Local Income Taxes, Net (4.9) (8.0) 2.7
Parent Company Loss Benefit 0.0 0.0 (5.6)
Tax Reform Excess ADIT Reversal (14.8) (31.1) (21.9)
Other (2.9) (3.4) (4.2)
Income Tax Expense/Benefit $ (25.2) $ (0.6) $ 9.4
Effective Income Tax Rate (9.40%) (0.30%) 4.90%
Net Deferred Tax Liability and Significant Temporary Differences      
Deferred Tax Assets $ 374.9 $ 336.4  
Deferred Tax Liabilities (1,464.6) (1,424.0)  
Property Related Temporary Differences (1,053.8) (989.6)  
Amounts Due from Customers for Future Federal Income Taxes 146.2 154.8  
Deferred State Income Taxes (208.7) (234.9)  
Regulatory Assets (114.1) (101.4)  
Net Operating Loss Carryforward 42.7 67.4  
Deferred Tax Assets, Tax Credit Carryforwards [Abstract]      
Tax Credit Carryforward 66.0 8.5  
All Other, Net 32.0 7.6  
Net Deferred Tax Liabilities (1,089.7) (1,087.6)  
Income Taxes (Textuals) [Abstract]      
Income Tax Expense/Benefit (25.2) (0.6) $ 9.4
Operating Income (Loss) $ (370.0) (339.5) (290.5)
Southwestern Electric Power Co [Member] | Minimum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2036    
Southwestern Electric Power Co [Member] | Maximum [Member]      
Income Taxes (Textuals) [Abstract]      
Tax Credit Carryforward, Expiration Date Dec. 31, 2041    
Arkansas      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 224.4    
Arkansas | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2023    
Arkansas | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2032    
Arkansas | Southwestern Electric Power Co [Member] | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2023    
Arkansas | Southwestern Electric Power Co [Member] | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2032    
Kentucky      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 231.3    
Kentucky | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2030    
Kentucky | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
Louisiana      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 586.8    
Louisiana | Southwestern Electric Power Co [Member]      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward 577.2    
Oklahoma      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 943.3    
Oklahoma | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
Oklahoma | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
Oklahoma | AEP Transmission Co [Member]      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 33.0    
Oklahoma | AEP Transmission Co [Member] | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
Oklahoma | AEP Transmission Co [Member] | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
Oklahoma | Public Service Co Of Oklahoma [Member]      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 899.6    
Oklahoma | Public Service Co Of Oklahoma [Member] | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
Oklahoma | Public Service Co Of Oklahoma [Member] | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
Tennessee      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 77.7    
Tennessee | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2030    
Tennessee | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
Virginia      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 11.2    
Virginia | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2030    
Virginia | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
West Virginia      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 12.3    
West Virginia | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2029    
West Virginia | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2037    
Ohio Municipal      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 1,257.7    
Ohio Municipal | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2023    
Ohio Municipal | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2027    
Ohio Municipal | Ohio Power Co [Member]      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 190.1    
Ohio Municipal | Ohio Power Co [Member] | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2024    
Ohio Municipal | Ohio Power Co [Member] | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2027    
Colorado      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 82.6    
Pennsylvania | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2030    
Pennsylvania | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2042    
Illinois      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 52.4    
Federal      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 612.0    
Federal | AEP Texas Inc. [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 1.5    
Federal | AEP Transmission Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 0.2    
Federal | Appalachian Power Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 2.0    
Federal | Indiana Michigan Power Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 11.4    
Federal | Ohio Power Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 1.0    
Federal | Public Service Co Of Oklahoma [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 54.3    
Federal | Southwestern Electric Power Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 66.0    
State and Local Jurisdiction      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 39.2    
State and Local Jurisdiction | AEP Texas Inc. [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 0.0    
State and Local Jurisdiction | AEP Transmission Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 0.0    
State and Local Jurisdiction | Appalachian Power Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 0.0    
State and Local Jurisdiction | Indiana Michigan Power Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 0.0    
State and Local Jurisdiction | Ohio Power Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 0.0    
State and Local Jurisdiction | Public Service Co Of Oklahoma [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 39.2    
State and Local Jurisdiction | Southwestern Electric Power Co [Member]      
Tax Credit Carryforward      
Tax Credit Carryforward, Amount 0.0    
MICHIGAN      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 58.7    
MICHIGAN | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2029    
MICHIGAN | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2031    
NEW JERSEY      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 13.7    
NEW JERSEY | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2036    
NEW JERSEY | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2040    
NEW MEXICO      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 22.9    
PENNSYLVANIA      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 64.4    
ILLINOIS | Minimum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2031    
ILLINOIS | Maximum [Member]      
Net Income Tax Operating Loss Carryforwards      
Operating Loss Carryforwards, Expiration Date Dec. 31, 2041    
Arkansas | Southwestern Electric Power Co [Member]      
Net Income Tax Operating Loss Carryforwards      
Net Income Tax Operating Loss Carryforward $ 224.2    
Dolet Hills Lignite Co, LLC [Member]      
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Less: Equity Earnings (1.4) (3.4) (2.9)
Dolet Hills Lignite Co, LLC [Member] | Southwestern Electric Power Co [Member]      
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Less: Equity Earnings (1.4) (3.4) (2.9)
Investment funds | Ohio Power Co [Member]      
Reconciliation of Federal Income Taxes and Amount of Income Tax Reported      
Less: Equity Earnings $ (0.6) $ 0.0 $ 0.0
[1] 2021 amount represents an out of period adjustment related to Deferred Income Taxes and Income Tax Expense (Benefit). Management concluded the misstatement and subsequent correction was not material to the 2021 or prior period financial statements.