v3.26.1
FAIR VALUE MEASUREMENTS - Fair Value of Assets and Liabilities on a Recurring Basis (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Assets:    
Restricted Cash $ 72 $ 71
Total Other Temporary Investments and Restricted Cash 300 291
Total Risk Management Assets 768 617
Total Spent Nuclear Fuel and Decommissioning Trusts 5,241 4,916
Total Assets 6,309 5,824
Liabilities:    
Total Risk Management Liabilities 327 310
AEP TEXAS INC.    
Assets:    
Restricted Cash 13 14
Total Risk Management Assets 0 0
Total Assets 13  
Liabilities:    
Total Risk Management Liabilities 0 0
APPALACHIAN POWER COMPANY    
Assets:    
Restricted Cash 25 18
Total Risk Management Assets 171 82
Total Assets 196 100
Liabilities:    
Total Risk Management Liabilities 12 3
INDIANA MICHIGAN POWER COMPANY    
Assets:    
Total Risk Management Assets 22 10
Total Spent Nuclear Fuel and Decommissioning Trusts 5,241 4,916
Total Assets 5,263 4,926
Liabilities:    
Total Risk Management Liabilities 0 0
OHIO POWER COMPANY    
Assets:    
Total Risk Management Assets 0 0
Liabilities:    
Total Risk Management Liabilities 28 33
PUBLIC SERVICE COMPANY OF OKLAHOMA    
Assets:    
Total Risk Management Assets 43 42
Liabilities:    
Total Risk Management Liabilities 28 28
SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Restricted Cash 14 15
Total Risk Management Assets 42 35
Total Assets 56 50
Liabilities:    
Total Risk Management Liabilities 13 11
Commodity    
Assets:    
Total Risk Management Assets 653 513
Liabilities:    
Total Risk Management Liabilities 292 274
Commodity | AEP TEXAS INC.    
Assets:    
Total Risk Management Assets 0  
Commodity | APPALACHIAN POWER COMPANY    
Assets:    
Total Risk Management Assets 171 82
Liabilities:    
Total Risk Management Liabilities 12 3
Commodity | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Total Risk Management Assets 22 10
Liabilities:    
Total Risk Management Liabilities 0 0
Commodity | OHIO POWER COMPANY    
Assets:    
Total Risk Management Assets 0  
Liabilities:    
Total Risk Management Liabilities 28 33
Commodity | PUBLIC SERVICE COMPANY OF OKLAHOMA    
Assets:    
Total Risk Management Assets 43 42
Liabilities:    
Total Risk Management Liabilities 28 28
Commodity | SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Total Risk Management Assets 42 35
Liabilities:    
Total Risk Management Liabilities 13 11
Commodity Contract, Cash Flow Hedging    
Assets:    
Total Risk Management Assets 115 104
Liabilities:    
Total Risk Management Liabilities 8 6
Fair Value Hedge Instruments    
Liabilities:    
Total Risk Management Liabilities 27 30
Other    
Assets:    
Restricted Cash 20 23
Total Other Temporary Investments and Restricted Cash 30 36
Risk management asset, offset (1,206) (727)
Total Spent Nuclear Fuel and Decommissioning Trusts 14 15
Assets including netting (1,162) (676)
Liabilities:    
Risk management liabilities, offset (1,108) (647)
Other | AEP TEXAS INC.    
Assets:    
Restricted Cash 0 0
Risk management asset, offset (1)  
Other | APPALACHIAN POWER COMPANY    
Assets:    
Restricted Cash 0 0
Risk management asset, offset (4) (2)
Other | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Total Spent Nuclear Fuel and Decommissioning Trusts 14 15
Assets including netting (16) 4
Other | SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Restricted Cash 0 0
Risk management asset, offset (1) (2)
Other | Commodity    
Assets:    
Risk management asset, offset (1,186) (713)
Liabilities:    
Risk management liabilities, offset (1,087) (633)
Other | Commodity | AEP TEXAS INC.    
Assets:    
Risk management asset, offset (1)  
Other | Commodity | APPALACHIAN POWER COMPANY    
Assets:    
Risk management asset, offset (4) (2)
Liabilities:    
Risk management liabilities, offset (4) (3)
Other | Commodity | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Risk management asset, offset (30) (11)
Liabilities:    
Risk management liabilities, offset (35) (11)
Other | Commodity | OHIO POWER COMPANY    
Assets:    
Risk management asset, offset (1)  
Liabilities:    
Risk management liabilities, offset 0 0
Other | Commodity | PUBLIC SERVICE COMPANY OF OKLAHOMA    
Assets:    
Risk management asset, offset (1) (2)
Liabilities:    
Risk management liabilities, offset (1) (2)
Other | Commodity | SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Risk management asset, offset (1) (2)
Liabilities:    
Risk management liabilities, offset 0 (2)
Other | Commodity Contract, Cash Flow Hedging    
Assets:    
Risk management asset, offset (20) (14)
Liabilities:    
Risk management liabilities, offset (21) (14)
Other | Fair Value Hedge Instruments    
Liabilities:    
Risk management liabilities, offset 0 0
Mutual Funds    
Assets:    
Fixed Income Securities: 173 165
Equity securities, fair value disclosure 45 42
Mutual Funds | Other    
Assets:    
Fixed Income Securities: 0 0
Equity securities, fair value disclosure 0 0
Subtotal Fixed Income Securities    
Assets:    
Fixed Income Securities: 1,734 1,727
Subtotal Fixed Income Securities | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 1,734 1,727
Subtotal Fixed Income Securities | Other    
Assets:    
Fixed Income Securities: 0 0
Subtotal Fixed Income Securities | Other | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 0 0
United States Government    
Assets:    
Fixed Income Securities: 1,322 1,351
United States Government | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 1,322 1,351
United States Government | Other    
Assets:    
Fixed Income Securities: 0 0
United States Government | Other | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 0 0
Corporate Debt    
Assets:    
Fixed Income Securities: 412 376
Corporate Debt | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 412 376
Corporate Debt | Other    
Assets:    
Fixed Income Securities: 0 0
Corporate Debt | Other | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 0 0
Equity Securities - Domestic    
Assets:    
Equity securities, fair value disclosure 3,485 3,160
Equity Securities - Domestic | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Equity securities, fair value disclosure 3,485 3,160
Equity Securities - Domestic | Other    
Assets:    
Equity securities, fair value disclosure 0 0
Equity Securities - Domestic | Other | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Equity securities, fair value disclosure 0 0
Other Cash Deposits    
Assets:    
Cash and cash equivalents, fair value disclosure 10 13
Other Cash Deposits | Other    
Assets:    
Cash and cash equivalents, fair value disclosure 10 13
Cash and Cash Equivalents    
Assets:    
Cash and cash equivalents, fair value disclosure 22 29
Cash and Cash Equivalents | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Cash and cash equivalents, fair value disclosure 22 29
Cash and Cash Equivalents | Other    
Assets:    
Cash and cash equivalents, fair value disclosure 14 15
Cash and Cash Equivalents | Other | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Cash and cash equivalents, fair value disclosure 14 15
Level 1 | Within Current Year    
Liabilities:    
Maturities of net fair value of risk management contracts (1) (2)
Level 1 | Maturity Period 2    
Liabilities:    
Maturities of net fair value of risk management contracts 2  
Level 1 | Estimate of Fair Value Measurement    
Assets:    
Restricted Cash 52 48
Total Other Temporary Investments and Restricted Cash 270 255
Risk Management Assets 5 2
Total Spent Nuclear Fuel and Decommissioning Trusts 3,493 3,174
Total Assets 3,768 3,431
Liabilities:    
Risk Management Liabilities 4 4
Level 1 | Estimate of Fair Value Measurement | AEP TEXAS INC.    
Assets:    
Restricted Cash 13 14
Total Assets 13  
Level 1 | Estimate of Fair Value Measurement | APPALACHIAN POWER COMPANY    
Assets:    
Restricted Cash 25 18
Total Assets 25 18
Level 1 | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Total Spent Nuclear Fuel and Decommissioning Trusts 3,493 3,174
Total Assets 3,493 3,174
Level 1 | Estimate of Fair Value Measurement | SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Restricted Cash 14 15
Total Assets 14 15
Level 1 | Estimate of Fair Value Measurement | Commodity    
Assets:    
Risk Management Assets 5 2
Liabilities:    
Risk Management Liabilities 4 4
Level 1 | Estimate of Fair Value Measurement | Commodity | AEP TEXAS INC.    
Assets:    
Risk Management Assets 0  
Level 1 | Estimate of Fair Value Measurement | Commodity | APPALACHIAN POWER COMPANY    
Assets:    
Risk Management Assets 0 0
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Commodity | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Risk Management Assets 0 0
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Commodity | OHIO POWER COMPANY    
Assets:    
Risk Management Assets 0  
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Commodity | PUBLIC SERVICE COMPANY OF OKLAHOMA    
Assets:    
Risk Management Assets 0 0
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Commodity | SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Risk Management Assets 0 0
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Commodity Contract, Cash Flow Hedging    
Assets:    
Risk Management Assets 0 0
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Fair Value Hedge Instruments    
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Mutual Funds | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 173 165
Equity securities, fair value disclosure 45 42
Level 1 | Subtotal Fixed Income Securities | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 0 0
Level 1 | Subtotal Fixed Income Securities | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 0 0
Level 1 | United States Government | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 0 0
Level 1 | United States Government | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 0 0
Level 1 | Corporate Debt | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 0 0
Level 1 | Corporate Debt | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 0 0
Level 1 | Equity Securities - Domestic | Estimate of Fair Value Measurement    
Assets:    
Equity securities, fair value disclosure 3,485 3,160
Level 1 | Equity Securities - Domestic | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Equity securities, fair value disclosure 3,485 3,160
Level 1 | Other Cash Deposits | Estimate of Fair Value Measurement    
Assets:    
Cash and cash equivalents, fair value disclosure 0 0
Level 1 | Cash and Cash Equivalents | Estimate of Fair Value Measurement    
Assets:    
Cash and cash equivalents, fair value disclosure 8 14
Level 1 | Cash and Cash Equivalents | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Cash and cash equivalents, fair value disclosure 8 14
Level 2 | Within Current Year    
Liabilities:    
Maturities of net fair value of risk management contracts 20 12
Level 2 | Maturity Period 2    
Liabilities:    
Maturities of net fair value of risk management contracts 76 65
Level 2 | Maturity Period 3    
Liabilities:    
Maturities of net fair value of risk management contracts 1 1
Level 2 | Estimate of Fair Value Measurement    
Assets:    
Restricted Cash 0 0
Total Other Temporary Investments and Restricted Cash 0 0
Risk Management Assets 1,414 931
Total Spent Nuclear Fuel and Decommissioning Trusts 1,734 1,727
Total Assets 3,148 2,658
Liabilities:    
Risk Management Liabilities 1,256 801
Level 2 | Estimate of Fair Value Measurement | AEP TEXAS INC.    
Assets:    
Restricted Cash 0 0
Total Assets 1  
Level 2 | Estimate of Fair Value Measurement | APPALACHIAN POWER COMPANY    
Assets:    
Restricted Cash 0 0
Total Assets 2 3
Level 2 | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Total Spent Nuclear Fuel and Decommissioning Trusts 1,734 1,727
Total Assets 1,760 1,739
Level 2 | Estimate of Fair Value Measurement | SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Restricted Cash 0 0
Total Assets 1 0
Level 2 | Estimate of Fair Value Measurement | Commodity    
Assets:    
Risk Management Assets 1,297 831
Liabilities:    
Risk Management Liabilities 1,201 752
Level 2 | Estimate of Fair Value Measurement | Commodity | AEP TEXAS INC.    
Assets:    
Risk Management Assets 1  
Level 2 | Estimate of Fair Value Measurement | Commodity | APPALACHIAN POWER COMPANY    
Assets:    
Risk Management Assets 2 3
Liabilities:    
Risk Management Liabilities 14 6
Level 2 | Estimate of Fair Value Measurement | Commodity | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Risk Management Assets 26 12
Liabilities:    
Risk Management Liabilities 31 11
Level 2 | Estimate of Fair Value Measurement | Commodity | OHIO POWER COMPANY    
Assets:    
Risk Management Assets 1  
Liabilities:    
Risk Management Liabilities 0 0
Level 2 | Estimate of Fair Value Measurement | Commodity | PUBLIC SERVICE COMPANY OF OKLAHOMA    
Assets:    
Risk Management Assets 1 1
Liabilities:    
Risk Management Liabilities 29 28
Level 2 | Estimate of Fair Value Measurement | Commodity | SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Risk Management Assets 1 0
Liabilities:    
Risk Management Liabilities 13 11
Level 2 | Estimate of Fair Value Measurement | Commodity Contract, Cash Flow Hedging    
Assets:    
Risk Management Assets 117 100
Liabilities:    
Risk Management Liabilities 28 19
Level 2 | Estimate of Fair Value Measurement | Fair Value Hedge Instruments    
Liabilities:    
Risk Management Liabilities 27 30
Level 2 | Mutual Funds | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 0 0
Equity securities, fair value disclosure 0 0
Level 2 | Subtotal Fixed Income Securities | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 1,734 1,727
Level 2 | Subtotal Fixed Income Securities | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 1,734 1,727
Level 2 | United States Government | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 1,322 1,351
Level 2 | United States Government | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 1,322 1,351
Level 2 | Corporate Debt | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 412 376
Level 2 | Corporate Debt | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 412 376
Level 2 | Equity Securities - Domestic | Estimate of Fair Value Measurement    
Assets:    
Equity securities, fair value disclosure 0 0
Level 2 | Equity Securities - Domestic | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Equity securities, fair value disclosure 0 0
Level 2 | Other Cash Deposits | Estimate of Fair Value Measurement    
Assets:    
Cash and cash equivalents, fair value disclosure 0 0
Level 2 | Cash and Cash Equivalents | Estimate of Fair Value Measurement    
Assets:    
Cash and cash equivalents, fair value disclosure 0 0
Level 2 | Cash and Cash Equivalents | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Cash and cash equivalents, fair value disclosure 0 0
Level 3 | Within Current Year    
Liabilities:    
Maturities of net fair value of risk management contracts 156 210
Level 3 | Maturity Period 2    
Liabilities:    
Maturities of net fair value of risk management contracts 224 51
Level 3 | Maturity Period 3    
Liabilities:    
Maturities of net fair value of risk management contracts (3) (6)
Level 3 | Maturity Period 4    
Liabilities:    
Maturities of net fair value of risk management contracts (14) (13)
Level 3 | Estimate of Fair Value Measurement    
Assets:    
Restricted Cash 0 0
Total Other Temporary Investments and Restricted Cash 0 0
Risk Management Assets 555 411
Total Spent Nuclear Fuel and Decommissioning Trusts 0 0
Total Assets 555 411
Liabilities:    
Risk Management Liabilities 175 152
Level 3 | Estimate of Fair Value Measurement | AEP TEXAS INC.    
Assets:    
Restricted Cash 0 0
Total Assets 0  
Level 3 | Estimate of Fair Value Measurement | APPALACHIAN POWER COMPANY    
Assets:    
Restricted Cash 0 0
Total Assets 173 81
Level 3 | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Total Spent Nuclear Fuel and Decommissioning Trusts 0 0
Total Assets 26 9
Level 3 | Estimate of Fair Value Measurement | SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Restricted Cash 0 0
Total Assets 42 37
Level 3 | Estimate of Fair Value Measurement | Commodity    
Assets:    
Risk Management Assets 537 393
Liabilities:    
Risk Management Liabilities 174 151
Level 3 | Estimate of Fair Value Measurement | Commodity | AEP TEXAS INC.    
Assets:    
Risk Management Assets 0  
Level 3 | Estimate of Fair Value Measurement | Commodity | APPALACHIAN POWER COMPANY    
Assets:    
Risk Management Assets 173 81
Liabilities:    
Risk Management Liabilities 2 0
Level 3 | Estimate of Fair Value Measurement | Commodity | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Risk Management Assets 26 9
Liabilities:    
Risk Management Liabilities 4 0
Level 3 | Estimate of Fair Value Measurement | Commodity | OHIO POWER COMPANY    
Assets:    
Risk Management Assets 0  
Liabilities:    
Risk Management Liabilities 28 33
Level 3 | Estimate of Fair Value Measurement | Commodity | PUBLIC SERVICE COMPANY OF OKLAHOMA    
Assets:    
Risk Management Assets 43 43
Liabilities:    
Risk Management Liabilities 0 2
Level 3 | Estimate of Fair Value Measurement | Commodity | SOUTHWESTERN ELECTRIC POWER COMPANY    
Assets:    
Risk Management Assets 42 37
Liabilities:    
Risk Management Liabilities 0 2
Level 3 | Estimate of Fair Value Measurement | Commodity Contract, Cash Flow Hedging    
Assets:    
Risk Management Assets 18 18
Liabilities:    
Risk Management Liabilities 1 1
Level 3 | Estimate of Fair Value Measurement | Fair Value Hedge Instruments    
Liabilities:    
Risk Management Liabilities 0 0
Level 3 | Mutual Funds | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 0 0
Equity securities, fair value disclosure 0 0
Level 3 | Subtotal Fixed Income Securities | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 0 0
Level 3 | Subtotal Fixed Income Securities | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 0 0
Level 3 | United States Government | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 0 0
Level 3 | United States Government | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 0 0
Level 3 | Corporate Debt | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 0 0
Level 3 | Corporate Debt | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Fixed Income Securities: 0 0
Level 3 | Equity Securities - Domestic | Estimate of Fair Value Measurement    
Assets:    
Equity securities, fair value disclosure 0 0
Level 3 | Equity Securities - Domestic | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Equity securities, fair value disclosure 0 0
Level 3 | Other Cash Deposits | Estimate of Fair Value Measurement    
Assets:    
Cash and cash equivalents, fair value disclosure 0 0
Level 3 | Cash and Cash Equivalents | Estimate of Fair Value Measurement    
Assets:    
Cash and cash equivalents, fair value disclosure 0 0
Level 3 | Cash and Cash Equivalents | Estimate of Fair Value Measurement | INDIANA MICHIGAN POWER COMPANY    
Assets:    
Cash and cash equivalents, fair value disclosure $ 0 $ 0