v3.24.0.1
Fair Value Financial Assets Liabilities (Details) - USD ($)
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Derivative Assets $ 538,700,000 $ 632,900,000  
Derivative Liabilities 471,400,000 490,400,000  
Assets, Fair Value Disclosure      
Other Temporary Investments 263,200,000 234,700,000  
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 3,860,200,000 3,341,200,000  
Total Assets 4,662,100,000 4,208,800,000  
Risk Management Assets      
Derivative Assets 538,700,000 632,900,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 471,400,000 490,400,000  
Changes in the Fair Value of Net Trading Derivatives and Other Investments      
Beginning Balance 160,400,000 103,100,000 $ 113,300,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets) [1],[2] 52,100,000 69,500,000 48,600,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date [2] 71,100,000 (34,900,000) (45,200,000)
Realized and Unrealized Gains (Losses) Included in Other Comprehensive Income [3] (17,400,000) 9,600,000 24,200,000
Settlements (172,200,000) (154,600,000) (89,000,000.0)
Transfers into Level 3 [4],[5] (6,100,000) 1,700,000 (3,800,000)
Transfers out of Level 3 [5] 3,800,000 100,000 (34,400,000)
Changes in Fair Value Allocated to Regulated Jurisdiction [6] 47,700,000 165,900,000 89,400,000
Ending Balance 139,400,000 160,400,000 103,100,000
Other [Member]      
Derivative Assets (625,500,000) (1,264,300,000)  
Derivative Liabilities (608,800,000) (784,700,000)  
Assets, Fair Value Disclosure      
Other Temporary Investments 13,900,000 9,000,000.0  
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 9,000,000.0 9,900,000  
Total Assets (602,600,000) (1,245,400,000)  
Risk Management Assets      
Derivative Assets (625,500,000) (1,264,300,000)  
Liabilities, Fair Value Disclosure      
Derivative Liabilities (608,800,000) (784,700,000)  
Level 1 [Member]      
Derivative Assets 9,700,000 15,000,000.0  
Derivative Liabilities 24,700,000 21,800,000  
Assets, Fair Value Disclosure      
Other Temporary Investments 249,300,000 225,700,000  
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 2,444,400,000 2,142,600,000  
Total Assets 2,703,400,000 2,383,300,000  
Risk Management Assets      
Derivative Assets 9,700,000 15,000,000.0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 24,700,000 21,800,000  
Level 2 [Member]      
Derivative Assets 860,400,000 1,541,100,000  
Derivative Liabilities 900,800,000 1,072,600,000  
Assets, Fair Value Disclosure      
Other Temporary Investments 0 0  
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,406,800,000 1,188,700,000  
Total Assets 2,267,200,000 2,729,800,000  
Risk Management Assets      
Derivative Assets 860,400,000 1,541,100,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 900,800,000 1,072,600,000  
Level 3 [Member]      
Derivative Assets 294,100,000 341,100,000  
Derivative Liabilities 154,700,000 180,700,000  
Assets, Fair Value Disclosure      
Other Temporary Investments 0 0  
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Total Assets 294,100,000 341,100,000  
Risk Management Assets      
Derivative Assets 294,100,000 341,100,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 154,700,000 180,700,000  
2023 [Member] | Level 1 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities   (7,000,000)  
2023 [Member] | Level 2 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities   182,000,000  
2023 [Member] | Level 3 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities   128,000,000  
2024 [Member] | Level 1 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities (11,000,000)    
2024 [Member] | Level 2 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities (99,000,000)    
2024 [Member] | Level 3 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities 74,000,000    
2024 - 2026 [Member] | Level 2 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities   134,000,000  
2024 - 2026 [Member] | Level 3 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities   6,000,000  
2025 - 2027 [Member] | Level 1 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities (4,000,000)    
2025 - 2027 [Member] | Level 2 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities (44,000,000)    
2025 - 2027 [Member] | Level 3 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities 43,000,000    
2027 - 2028 [Member] | Level 2 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities   10,000,000  
2027 - 2028 [Member] | Level 3 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities   6,000,000  
2028-2029 [Member] | Level 2 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities 7,000,000    
2028-2029 [Member] | Level 3 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities 18,000,000    
2029 - 2033 [Member] | Level 2 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities   1,000,000  
2029 - 2033 [Member] | Level 3 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities   (5,000,000)  
2030 - 2033 [Member] | Level 2 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities 2,000,000    
2030 - 2033 [Member] | Level 3 [Member]      
Fair Value Measurements 1 (Textuals)      
Maturity Of Net Fair Value Of Risk Management Contracts Prior to Cash Collateral, Assets/Liabilities (16,000,000)    
Risk Management Commodity Contracts [Member]      
Derivative Assets [8] 403,900,000 [7] 315,400,000 [9]  
Derivative Liabilities [8] 362,300,000 [7] 339,800,000 [9]  
Risk Management Assets      
Derivative Assets [8] 403,900,000 [7] 315,400,000 [9]  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 362,300,000 [7] 339,800,000 [9]  
Risk Management Commodity Contracts [Member] | Other [Member]      
Derivative Assets [8] (617,000,000.0) [7] (1,211,500,000) [9]  
Derivative Liabilities [8] (600,300,000) [7] (731,900,000) [9]  
Risk Management Assets      
Derivative Assets [8] (617,000,000.0) [7] (1,211,500,000) [9]  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] (600,300,000) [7] (731,900,000) [9]  
Risk Management Commodity Contracts [Member] | Level 1 [Member]      
Derivative Assets [8] 9,700,000 [7] 15,000,000.0 [9]  
Derivative Liabilities [8] 24,700,000 [7] 21,800,000 [9]  
Risk Management Assets      
Derivative Assets [8] 9,700,000 [7] 15,000,000.0 [9]  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 24,700,000 [7] 21,800,000 [9]  
Risk Management Commodity Contracts [Member] | Level 2 [Member]      
Derivative Assets [8] 736,900,000 [7] 1,197,500,000 [9]  
Derivative Liabilities [8] 783,800,000 [7] 870,900,000 [9]  
Risk Management Assets      
Derivative Assets [8] 736,900,000 [7] 1,197,500,000 [9]  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 783,800,000 [7] 870,900,000 [9]  
Risk Management Commodity Contracts [Member] | Level 3 [Member]      
Derivative Assets [8] 274,300,000 [7] 314,400,000 [9]  
Derivative Liabilities [8] 154,100,000 [7] 179,000,000.0 [9]  
Risk Management Assets      
Derivative Assets [8] 274,300,000 [7] 314,400,000 [9]  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 154,100,000 [7] 179,000,000.0 [9]  
Energy Contracts [Member] | Level 3 [Member]      
Derivative Assets 225,500,000 204,000,000.0  
Derivative Liabilities 144,900,000 167,400,000  
Risk Management Assets      
Derivative Assets 225,500,000 204,000,000.0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 144,900,000 167,400,000  
Energy Contracts [Member] | Level 3 [Member] | Low [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] 5.21 2.91  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] 5.21 2.91  
Energy Contracts [Member] | Level 3 [Member] | High [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] 153.77 187.34  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] 153.77 187.34  
Energy Contracts [Member] | Level 3 [Member] | Weighted Average [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 45.05 49.14  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 45.05 49.14  
Natural Gas Contracts [Member] | Level 3 [Member]      
Derivative Assets 0    
Derivative Liabilities 500,000    
Risk Management Assets      
Derivative Assets 0    
Liabilities, Fair Value Disclosure      
Derivative Liabilities 500,000    
Natural Gas Contracts [Member] | Level 3 [Member] | Low [Member]      
Fair Value Significant Unobservable Input Price Per Unit [12] 3.11    
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [12] 3.11    
Natural Gas Contracts [Member] | Level 3 [Member] | High [Member]      
Fair Value Significant Unobservable Input Price Per Unit [12] 3.11    
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [12] 3.11    
Natural Gas Contracts [Member] | Level 3 [Member] | Weighted Average [Member]      
Fair Value Significant Unobservable Input Price Per Unit [11],[12] 3.11    
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [11],[12] 3.11    
FTRs [Member] | Level 3 [Member]      
Derivative Assets 68,600,000 137,100,000  
Derivative Liabilities 9,300,000 13,300,000  
Risk Management Assets      
Derivative Assets 68,600,000 137,100,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 9,300,000 13,300,000  
FTRs [Member] | Level 3 [Member] | Low [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] (25.45) (36.45)  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] (25.45) (36.45)  
FTRs [Member] | Level 3 [Member] | High [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] 17.07 20.72  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] 17.07 20.72  
FTRs [Member] | Level 3 [Member] | Weighted Average [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 0 1.18  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 0 1.18  
Commodity Hedges [Member]      
Derivative Assets [8] 134,800,000 306,500,000  
Derivative Liabilities [8] 1,700,000 23,200,000  
Risk Management Assets      
Derivative Assets [8] 134,800,000 306,500,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 1,700,000 23,200,000  
Commodity Hedges [Member] | Other [Member]      
Derivative Assets [8] (8,500,000) (52,800,000)  
Derivative Liabilities [8] (8,500,000) (52,800,000)  
Risk Management Assets      
Derivative Assets [8] (8,500,000) (52,800,000)  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] (8,500,000) (52,800,000)  
Commodity Hedges [Member] | Level 1 [Member]      
Derivative Assets [8] 0 0  
Derivative Liabilities [8] 0 0  
Risk Management Assets      
Derivative Assets [8] 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 0 0  
Commodity Hedges [Member] | Level 2 [Member]      
Derivative Assets [8] 123,500,000 332,600,000  
Derivative Liabilities [8] 9,600,000 74,300,000  
Risk Management Assets      
Derivative Assets [8] 123,500,000 332,600,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 9,600,000 74,300,000  
Commodity Hedges [Member] | Level 3 [Member]      
Derivative Assets [8] 19,800,000 26,700,000  
Derivative Liabilities [8] 600,000 1,700,000  
Risk Management Assets      
Derivative Assets [8] 19,800,000 26,700,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 600,000 1,700,000  
Fair Value Hedges [Member]      
Derivative Liabilities 98,400,000 127,400,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 98,400,000 127,400,000  
Fair Value Hedges [Member] | Other [Member]      
Derivative Liabilities 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0 0  
Fair Value Hedges [Member] | Level 1 [Member]      
Derivative Liabilities 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0 0  
Fair Value Hedges [Member] | Level 2 [Member]      
Derivative Liabilities 98,400,000 127,400,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 98,400,000 127,400,000  
Fair Value Hedges [Member] | Level 3 [Member]      
Derivative Liabilities 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0 0  
Interest Rate Foreign Currency Hedges [Member]      
Derivative Assets   11,000,000.0  
Derivative Liabilities 9,000,000.0    
Risk Management Assets      
Derivative Assets   11,000,000.0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 9,000,000.0    
Interest Rate Foreign Currency Hedges [Member] | Other [Member]      
Derivative Assets   0  
Derivative Liabilities 0    
Risk Management Assets      
Derivative Assets   0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0    
Interest Rate Foreign Currency Hedges [Member] | Level 1 [Member]      
Derivative Assets   0  
Derivative Liabilities 0    
Risk Management Assets      
Derivative Assets   0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0    
Interest Rate Foreign Currency Hedges [Member] | Level 2 [Member]      
Derivative Assets   11,000,000.0  
Derivative Liabilities 9,000,000.0    
Risk Management Assets      
Derivative Assets   11,000,000.0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 9,000,000.0    
Interest Rate Foreign Currency Hedges [Member] | Level 3 [Member]      
Derivative Assets   0  
Derivative Liabilities 0    
Risk Management Assets      
Derivative Assets   0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0    
AEP Texas Inc. [Member]      
Derivative Liabilities 2,700,000    
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 34,000,000.0 32,700,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 2,700,000    
AEP Texas Inc. [Member] | Other [Member]      
Derivative Liabilities (200,000)    
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities (200,000)    
AEP Texas Inc. [Member] | Level 1 [Member]      
Derivative Liabilities 0    
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 34,000,000.0 32,700,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0    
AEP Texas Inc. [Member] | Level 2 [Member]      
Derivative Liabilities 2,900,000    
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 2,900,000    
AEP Texas Inc. [Member] | Level 3 [Member]      
Derivative Liabilities 0    
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0    
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member]      
Derivative Liabilities [8] 0    
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 0    
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Other [Member]      
Derivative Liabilities [8] (200,000)    
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] (200,000)    
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]      
Derivative Liabilities [8] 0    
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 0    
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]      
Derivative Liabilities [8] 200,000    
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 200,000    
AEP Texas Inc. [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]      
Derivative Liabilities [8] 0    
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 0    
AEP Texas Inc. [Member] | Interest Rate Foreign Currency Hedges [Member]      
Derivative Liabilities 2,700,000    
Liabilities, Fair Value Disclosure      
Derivative Liabilities 2,700,000    
AEP Texas Inc. [Member] | Interest Rate Foreign Currency Hedges [Member] | Other [Member]      
Derivative Liabilities 0    
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0    
AEP Texas Inc. [Member] | Interest Rate Foreign Currency Hedges [Member] | Level 1 [Member]      
Derivative Liabilities 0    
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0    
AEP Texas Inc. [Member] | Interest Rate Foreign Currency Hedges [Member] | Level 2 [Member]      
Derivative Liabilities 2,700,000    
Liabilities, Fair Value Disclosure      
Derivative Liabilities 2,700,000    
AEP Texas Inc. [Member] | Interest Rate Foreign Currency Hedges [Member] | Level 3 [Member]      
Derivative Liabilities 0    
Liabilities, Fair Value Disclosure      
Derivative Liabilities 0    
Appalachian Power Co [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 14,900,000 14,400,000  
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets 37,300,000 83,500,000  
Changes in the Fair Value of Net Trading Derivatives and Other Investments      
Beginning Balance 69,100,000 41,700,000 19,300,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets) [1],[2] (11,700,000) 3,000,000.0 8,300,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date [2] 0 0 0
Realized and Unrealized Gains (Losses) Included in Other Comprehensive Income [3] 0 0 0
Settlements (57,300,000) (44,700,000) (28,000,000.0)
Transfers into Level 3 [4],[5] 0 0 0
Transfers out of Level 3 [5] 0 0 0
Changes in Fair Value Allocated to Regulated Jurisdiction [6] 22,300,000 69,100,000 42,100,000
Ending Balance 22,400,000 69,100,000 41,700,000
Appalachian Power Co [Member] | Other [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 0 0  
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets (2,200,000) (1,000,000.0)  
Appalachian Power Co [Member] | Level 1 [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 14,900,000 14,400,000  
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets 14,900,000 14,400,000  
Appalachian Power Co [Member] | Level 2 [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 0 0  
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets 1,100,000 700,000  
Appalachian Power Co [Member] | Level 3 [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 0 0  
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets 23,500,000 69,400,000  
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member]      
Derivative Assets [8] 22,400,000 69,100,000  
Derivative Liabilities [8] 22,500,000 3,500,000  
Risk Management Assets      
Derivative Assets [8] 22,400,000 69,100,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 22,500,000 3,500,000  
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]      
Derivative Assets [8] (2,200,000) (1,000,000.0)  
Derivative Liabilities [8] (2,600,000) (1,400,000)  
Risk Management Assets      
Derivative Assets [8] (2,200,000) (1,000,000.0)  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] (2,600,000) (1,400,000)  
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]      
Derivative Assets [8] 0 0  
Derivative Liabilities [8] 0 0  
Risk Management Assets      
Derivative Assets [8] 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 0 0  
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]      
Derivative Assets [8] 1,100,000 700,000  
Derivative Liabilities [8] 24,000,000.0 4,600,000  
Risk Management Assets      
Derivative Assets [8] 1,100,000 700,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 24,000,000.0 4,600,000  
Appalachian Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]      
Derivative Assets [8] 23,500,000 69,400,000  
Derivative Liabilities [8] 1,100,000 300,000  
Risk Management Assets      
Derivative Assets [8] 23,500,000 69,400,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 1,100,000 300,000  
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member]      
Derivative Assets 23,500,000 69,400,000  
Derivative Liabilities 1,100,000 300,000  
Risk Management Assets      
Derivative Assets 23,500,000 69,400,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 1,100,000 300,000  
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member] | Low [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] (1.04) (2.82)  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] (1.04) (2.82)  
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member] | High [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] 6.45 18.88  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] 6.45 18.88  
Appalachian Power Co [Member] | FTRs [Member] | Level 3 [Member] | Weighted Average [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 1.36 3.89  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 1.36 3.89  
Indiana Michigan Power Co [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 3,860,200,000 3,341,200,000  
Total Assets 3,899,800,000 3,356,600,000  
Changes in the Fair Value of Net Trading Derivatives and Other Investments      
Beginning Balance 4,600,000 (700,000) 2,100,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets) [1],[2] 4,200,000 3,700,000 (100,000)
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date [2] 0 0 0
Realized and Unrealized Gains (Losses) Included in Other Comprehensive Income [3] 0 0 0
Settlements (8,800,000) (3,000,000.0) (2,200,000)
Transfers into Level 3 [4],[5] 0 0 0
Transfers out of Level 3 [5] 0 0 0
Changes in Fair Value Allocated to Regulated Jurisdiction [6] 2,800,000 4,600,000 (500,000)
Ending Balance 2,800,000 4,600,000 (700,000)
Indiana Michigan Power Co [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 9,000,000.0 9,900,000  
Total Assets 6,700,000 8,700,000  
Indiana Michigan Power Co [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 2,444,400,000 2,142,600,000  
Total Assets 2,444,400,000 2,142,600,000  
Indiana Michigan Power Co [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,406,800,000 1,188,700,000  
Total Assets 1,444,200,000 1,200,000,000  
Indiana Michigan Power Co [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Total Assets 4,500,000 5,300,000  
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member]      
Derivative Assets [8] 39,600,000 15,400,000  
Derivative Liabilities [8] 2,000,000.0 0  
Risk Management Assets      
Derivative Assets [8] 39,600,000 15,400,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 2,000,000.0 0  
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]      
Derivative Assets [8] (2,300,000) (1,200,000)  
Derivative Liabilities [8] (3,400,000) (1,300,000)  
Risk Management Assets      
Derivative Assets [8] (2,300,000) (1,200,000)  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] (3,400,000) (1,300,000)  
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]      
Derivative Assets [8] 0 0  
Derivative Liabilities [8] 0 0  
Risk Management Assets      
Derivative Assets [8] 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 0 0  
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]      
Derivative Assets [8] 37,400,000 11,300,000  
Derivative Liabilities [8] 3,700,000 600,000  
Risk Management Assets      
Derivative Assets [8] 37,400,000 11,300,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 3,700,000 600,000  
Indiana Michigan Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]      
Derivative Assets [8] 4,500,000 5,300,000  
Derivative Liabilities [8] 1,700,000 700,000  
Risk Management Assets      
Derivative Assets [8] 4,500,000 5,300,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 1,700,000 700,000  
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member]      
Derivative Assets 4,500,000 5,300,000  
Derivative Liabilities 1,700,000 700,000  
Risk Management Assets      
Derivative Assets 4,500,000 5,300,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 1,700,000 700,000  
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member] | Low [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] (1.48) 0.16  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] (1.48) 0.16  
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member] | High [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] 8.40 18.79  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] 8.40 18.79  
Indiana Michigan Power Co [Member] | FTRs [Member] | Level 3 [Member] | Weighted Average [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 0.85 1.23  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 0.85 1.23  
Ohio Power Co [Member]      
Changes in the Fair Value of Net Trading Derivatives and Other Investments      
Beginning Balance (40,000,000.0) (92,500,000) (110,300,000)
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets) [1],[2] (3,600,000) 6,500,000 2,400,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date [2] 0 0 0
Realized and Unrealized Gains (Losses) Included in Other Comprehensive Income [3] 0 0 0
Settlements 5,600,000 300,000 6,300,000
Transfers into Level 3 [4],[5] 0 0 0
Transfers out of Level 3 [5] 0 0 0
Changes in Fair Value Allocated to Regulated Jurisdiction [6] (12,600,000) 45,700,000 9,100,000
Ending Balance (50,600,000) (40,000,000.0) (92,500,000)
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member]      
Derivative Liabilities [8] 50,700,000 39,700,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 50,700,000 39,700,000  
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]      
Derivative Liabilities [8] (100,000) (300,000)  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] (100,000) (300,000)  
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]      
Derivative Liabilities [8] 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 0 0  
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]      
Derivative Liabilities [8] 200,000 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 200,000 0  
Ohio Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]      
Derivative Liabilities [8] 50,600,000 40,000,000.0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 50,600,000 40,000,000.0  
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member]      
Derivative Assets 0 0  
Derivative Liabilities 50,600,000 40,000,000.0  
Risk Management Assets      
Derivative Assets 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 50,600,000 40,000,000.0  
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | Low [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] 22.92 2.91  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] 22.92 2.91  
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | High [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] 67.53 187.34  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] 67.53 187.34  
Ohio Power Co [Member] | Energy Contracts [Member] | Level 3 [Member] | Weighted Average [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 42.85 48.76  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] 42.85 48.76  
Public Service Co Of Oklahoma [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets   25,300,000  
Changes in the Fair Value of Net Trading Derivatives and Other Investments      
Beginning Balance 23,700,000 12,100,000 10,300,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets) [1],[2] 29,800,000 24,200,000 16,100,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date [2] 0 0 0
Realized and Unrealized Gains (Losses) Included in Other Comprehensive Income [3] 0 0 0
Settlements (53,400,000) (36,300,000) (26,400,000)
Transfers into Level 3 [4],[5] 0 0 0
Transfers out of Level 3 [5] 0 0 0
Changes in Fair Value Allocated to Regulated Jurisdiction [6] 18,500,000 23,700,000 12,100,000
Ending Balance 18,600,000 23,700,000 12,100,000
Public Service Co Of Oklahoma [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets   (300,000)  
Public Service Co Of Oklahoma [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets   0  
Public Service Co Of Oklahoma [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets   1,600,000  
Public Service Co Of Oklahoma [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Total Assets   24,000,000.0  
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member]      
Derivative Assets [8] 19,000,000.0 25,300,000  
Derivative Liabilities [8] 29,900,000 1,600,000  
Risk Management Assets      
Derivative Assets [8] 19,000,000.0 25,300,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 29,900,000 1,600,000  
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Other [Member]      
Derivative Assets [8] (700,000) 1,300,000  
Derivative Liabilities [8] (800,000) (400,000)  
Risk Management Assets      
Derivative Assets [8] (700,000) 1,300,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] (800,000) (400,000)  
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]      
Derivative Assets [8] 0 0  
Derivative Liabilities [8] 0 0  
Risk Management Assets      
Derivative Assets [8] 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 0 0  
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]      
Derivative Assets [8] 0 0  
Derivative Liabilities [8] 29,600,000 1,700,000  
Risk Management Assets      
Derivative Assets [8] 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 29,600,000 1,700,000  
Public Service Co Of Oklahoma [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]      
Derivative Assets [8] 19,700,000 24,000,000.0  
Derivative Liabilities [8] 1,100,000 300,000  
Risk Management Assets      
Derivative Assets [8] 19,700,000 24,000,000.0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 1,100,000 300,000  
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member]      
Derivative Assets 19,700,000 24,000,000.0  
Derivative Liabilities 1,100,000 300,000  
Risk Management Assets      
Derivative Assets 19,700,000 24,000,000.0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 1,100,000 300,000  
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member] | Low [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] (25.45) (36.45)  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] (25.45) (36.45)  
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member] | High [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] 4.80 3.40  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] 4.80 3.40  
Public Service Co Of Oklahoma [Member] | FTRs [Member] | Level 3 [Member] | Weighted Average [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] (4.33) (7.55)  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] (4.33) (7.55)  
Public Service Co Of Oklahoma [Member] | Interest Rate Foreign Currency Hedges [Member]      
Derivative Assets   0  
Risk Management Assets      
Derivative Assets   0  
Public Service Co Of Oklahoma [Member] | Interest Rate Foreign Currency Hedges [Member] | Other [Member]      
Derivative Assets   (1,600,000)  
Risk Management Assets      
Derivative Assets   (1,600,000)  
Public Service Co Of Oklahoma [Member] | Interest Rate Foreign Currency Hedges [Member] | Level 1 [Member]      
Derivative Assets   0  
Risk Management Assets      
Derivative Assets   0  
Public Service Co Of Oklahoma [Member] | Interest Rate Foreign Currency Hedges [Member] | Level 2 [Member]      
Derivative Assets   1,600,000  
Risk Management Assets      
Derivative Assets   1,600,000  
Public Service Co Of Oklahoma [Member] | Interest Rate Foreign Currency Hedges [Member] | Level 3 [Member]      
Derivative Assets   0  
Risk Management Assets      
Derivative Assets   0  
Southwestern Electric Power Co [Member]      
Changes in the Fair Value of Net Trading Derivatives and Other Investments      
Beginning Balance 14,200,000 10,900,000 1,600,000
Realized Gain (Loss) Included in Net Income (or Changes in Net Assets) [1],[2] 20,000,000.0 35,800,000 9,500,000
Unrealized Gain (Loss) Included in Net Income (or Changes in Net Assets) Relating to Assets Still Held at the Reporting Date [2] 0 0 0
Realized and Unrealized Gains (Losses) Included in Other Comprehensive Income [3] 0 0 0
Settlements (34,200,000) (45,000,000.0) (15,500,000)
Transfers into Level 3 [4],[5] 0 0 0
Transfers out of Level 3 [5] 0 6,900,000 0
Changes in Fair Value Allocated to Regulated Jurisdiction [6] 11,100,000 5,600,000 15,300,000
Ending Balance 11,100,000 14,200,000 $ 10,900,000
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member]      
Derivative Assets [8] 11,600,000 16,400,000  
Derivative Liabilities [8] 15,600,000 1,400,000  
Risk Management Assets      
Derivative Assets [8] 11,600,000 16,400,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 15,600,000 1,400,000  
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Other [Member]      
Derivative Assets [8] (900,000) (400,000)  
Derivative Liabilities [8] (1,000,000.0) (600,000)  
Risk Management Assets      
Derivative Assets [8] (900,000) (400,000)  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] (1,000,000.0) (600,000)  
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 1 [Member]      
Derivative Assets [8] 0 0  
Derivative Liabilities [8] 0 0  
Risk Management Assets      
Derivative Assets [8] 0 0  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 0 0  
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 2 [Member]      
Derivative Assets [8] 500,000 2,200,000  
Derivative Liabilities [8] 15,700,000 1,600,000  
Risk Management Assets      
Derivative Assets [8] 500,000 2,200,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 15,700,000 1,600,000  
Southwestern Electric Power Co [Member] | Risk Management Commodity Contracts [Member] | Level 3 [Member]      
Derivative Assets [8] 12,000,000.0 14,600,000  
Derivative Liabilities [8] 900,000 400,000  
Risk Management Assets      
Derivative Assets [8] 12,000,000.0 14,600,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities [8] 900,000 400,000  
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member]      
Derivative Assets 0    
Derivative Liabilities 500,000    
Risk Management Assets      
Derivative Assets 0    
Liabilities, Fair Value Disclosure      
Derivative Liabilities 500,000    
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member] | Low [Member]      
Fair Value Significant Unobservable Input Price Per Unit [12] 3.11    
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [12] 3.11    
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member] | High [Member]      
Fair Value Significant Unobservable Input Price Per Unit [12] 3.11    
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [12] 3.11    
Southwestern Electric Power Co [Member] | Natural Gas Contracts [Member] | Level 3 [Member] | Weighted Average [Member]      
Fair Value Significant Unobservable Input Price Per Unit [11],[12] 3.11    
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [11],[12] 3.11    
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member]      
Derivative Assets 12,000,000.0 14,600,000  
Derivative Liabilities 400,000 400,000  
Risk Management Assets      
Derivative Assets 12,000,000.0 14,600,000  
Liabilities, Fair Value Disclosure      
Derivative Liabilities 400,000 400,000  
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member] | Low [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] (25.45) (36.45)  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] (25.45) (36.45)  
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member] | High [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10] 4.80 3.40  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10] 4.80 3.40  
Southwestern Electric Power Co [Member] | FTRs [Member] | Level 3 [Member] | Weighted Average [Member]      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] (4.33) (7.55)  
Level 3 Quantitative Information      
Fair Value Significant Unobservable Input Price Per Unit [10],[11] (4.33) (7.55)  
Cash [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 48,900,000 47,100,000  
Other Temporary Investments [13] 48,900,000 47,100,000  
Cash [Member] | Other [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 0 0  
Cash [Member] | Level 1 [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 48,900,000 47,100,000  
Cash [Member] | Level 2 [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 0 0  
Cash [Member] | Level 3 [Member]      
Assets, Fair Value Disclosure      
Cash and Cash Equivalents 0 0  
Other Cash Deposits [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments 13,900,000 9,000,000.0  
Other Cash Deposits [Member] | Other [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments [14] 13,900,000 9,000,000.0  
Other Cash Deposits [Member] | Level 1 [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments 0 0  
Other Cash Deposits [Member] | Level 2 [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments 0 0  
Other Cash Deposits [Member] | Level 3 [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments 0 0  
Mutual Funds Fixed Income [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments [15] 159,700,000 144,100,000  
Mutual Funds Fixed Income [Member] | Other [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments 0 0  
Mutual Funds Fixed Income [Member] | Level 1 [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments 159,700,000 144,100,000  
Mutual Funds Fixed Income [Member] | Level 2 [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments 0 0  
Mutual Funds Fixed Income [Member] | Level 3 [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments 0 0  
Mutual Funds Equity [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments [16] 40,700,000 34,500,000  
Mutual Funds Equity [Member] | Other [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments [16] 0 0  
Mutual Funds Equity [Member] | Level 1 [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments [16] 40,700,000 34,500,000  
Mutual Funds Equity [Member] | Level 2 [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments [16] 0 0  
Mutual Funds Equity [Member] | Level 3 [Member]      
Assets, Fair Value Disclosure      
Other Temporary Investments [16] 0 0  
Cash and Cash Equivalents [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 16,800,000 21,200,000  
Cash and Cash Equivalents [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 9,000,000.0 9,900,000  
Cash and Cash Equivalents [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 7,800,000 11,300,000  
Cash and Cash Equivalents [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 0 0  
Cash and Cash Equivalents [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 0 0  
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 16,800,000 21,200,000  
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 9,000,000.0 9,900,000  
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 7,800,000 11,300,000  
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 0 0  
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [17] 0 0  
US Government Agencies Debt Securities [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,273,000,000 1,123,800,000  
US Government Agencies Debt Securities [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
US Government Agencies Debt Securities [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
US Government Agencies Debt Securities [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,273,000,000 1,123,800,000  
US Government Agencies Debt Securities [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,273,000,000 1,123,800,000  
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,273,000,000 1,123,800,000  
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Corporate Debt Securities [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 132,100,000 61,600,000  
Corporate Debt Securities [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Corporate Debt Securities [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Corporate Debt Securities [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 132,100,000 61,600,000  
Corporate Debt Securities [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Corporate Debt Securities [Member] | Indiana Michigan Power Co [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 132,100,000 61,600,000  
Corporate Debt Securities [Member] | Indiana Michigan Power Co [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Corporate Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Corporate Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 132,100,000 61,600,000  
Corporate Debt Securities [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
State and Local Jurisdiction      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,700,000 3,300,000  
State and Local Jurisdiction | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
State and Local Jurisdiction | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
State and Local Jurisdiction | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,700,000 3,300,000  
State and Local Jurisdiction | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
State and Local Jurisdiction | Indiana Michigan Power Co [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,700,000 3,300,000  
State and Local Jurisdiction | Indiana Michigan Power Co [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
State and Local Jurisdiction | Indiana Michigan Power Co [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
State and Local Jurisdiction | Indiana Michigan Power Co [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,700,000 3,300,000  
State and Local Jurisdiction | Indiana Michigan Power Co [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Fixed Income Funds [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,406,800,000 1,188,700,000  
Fixed Income Funds [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Fixed Income Funds [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Fixed Income Funds [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,406,800,000 1,188,700,000  
Fixed Income Funds [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,406,800,000 1,188,700,000  
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 1,406,800,000 1,188,700,000  
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts 0 0  
Domestic [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] 2,436,600,000 2,131,300,000  
Domestic [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] 0 0  
Domestic [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] 2,436,600,000 2,131,300,000  
Domestic [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] 0 0  
Domestic [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] 0 0  
Domestic [Member] | Indiana Michigan Power Co [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] 2,436,600,000 2,131,300,000  
Domestic [Member] | Indiana Michigan Power Co [Member] | Other [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] 0 0  
Domestic [Member] | Indiana Michigan Power Co [Member] | Level 1 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] 2,436,600,000 2,131,300,000  
Domestic [Member] | Indiana Michigan Power Co [Member] | Level 2 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] 0 0  
Domestic [Member] | Indiana Michigan Power Co [Member] | Level 3 [Member]      
Spent Nuclear Fuel and Decommissioning Trusts      
Spent Nuclear Fuel and Decommissioning Trusts [16] $ 0 $ 0  
[1] Represents the change in fair value between the beginning of the reporting period and the settlement of the risk management commodity contract.
[2] Included in revenues on the statements of income.
[3] Included in cash flow hedges on the statements of comprehensive income.
[4] Represents existing assets or liabilities that were previously categorized as Level 2.
[5] Transfers are recognized based on their value at the beginning of the reporting period that the transfer occurred.
[6] Relates to the net gains (losses) of those contracts that are not reflected on the statements of income.  These changes in fair value are recorded as regulatory liabilities for net gains and as regulatory assets for net losses or accounts payable
[7] The December 31, 2023 maturities of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), were as follows: Level 1 matures $(11) million in 2024 and $(4) million in 2025-2027; Level 2 matures $(99) million in 2024, $(44) million in periods 2025-2027, $7 million in periods 2028-2029 and $2 million in periods 2030-2033; Level 3 matures $74 million in 2024, $43 million in periods 2025-2027, $18 million in periods 2028-2029 and $(16) million in periods 2030-2033. Risk management commodity contracts are substantially comprised of power contracts.
[8] Amounts in “Other” column primarily represent counterparty netting of risk management and hedging contracts and associated cash collateral under the accounting guidance for “Derivatives and Hedging.”
[9] The December 31, 2022 maturities of the net fair value of risk management contracts prior to cash collateral, assets/(liabilities), were as follows:  Level 1 matures $(7) million in 2023; Level 2 matures $182 million in 2023, $134 million in periods 2024-2026; $10 million in periods 2027-2028 and $1 million in periods 2029-2033; Level 3 matures $128 million in 2023, $6 million in periods 2024-2026, $6 million in periods 2027-2028 and $(5) million in periods 2029-2033.  Risk management commodity contracts are substantially comprised of power contracts.
[10] Represents market prices in dollars per MWh.
[11] The weighted-average is the product of the forward market price of the underlying commodity and volume weighted by term.
[12] Represents market prices in dollars per MMBtu.
[13] Primarily represents amounts held for the repayment of debt.
[14] Amounts in “Other” column primarily represent cash deposits in bank accounts with financial institutions or third-parties. Level 1 and Level 2 amounts primarily represent investments in money market funds.
[15] Primarily short and intermediate maturities which may be sold and do not contain maturity dates.
[16] Amounts represent publicly-traded equity securities and equity-based mutual funds.
[17] Amounts in “Other” column primarily represent accrued interest receivables from financial institutions.  Level 1 amounts primarily represent investments in money market funds.