v3.26.3
FAIR VALUE MEASUREMENTS - Fair Value of Assets and Liabilities on a Recurring Basis (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Assets:    
Restricted Cash $ 89 $ 71
Total Other Temporary Investments and Restricted Cash 341 291
Total Risk Management Assets 854 617
Total Spent Nuclear Fuel and Decommissioning Trusts 5,256 4,916
Total Assets 6,451 5,824
Liabilities:    
Total Risk Management Liabilities 423 310
AEP Texas    
Assets:    
Restricted Cash 9 14
Total Risk Management Assets 0 0
Total Assets 9  
Liabilities:    
Total Risk Management Liabilities 0 0
APCo    
Assets:    
Restricted Cash 60 18
Total Risk Management Assets 188 82
Total Assets 248 100
Liabilities:    
Total Risk Management Liabilities 18 3
I&M    
Assets:    
Total Risk Management Assets 26 10
Total Spent Nuclear Fuel and Decommissioning Trusts 5,256 4,916
Total Assets 5,282 4,926
Liabilities:    
Total Risk Management Liabilities 1 0
OPCo    
Assets:    
Total Risk Management Assets 0 0
Liabilities:    
Total Risk Management Liabilities 22 33
PSO    
Assets:    
Total Risk Management Assets 41 42
Liabilities:    
Total Risk Management Liabilities 34 28
SWEPCo    
Assets:    
Restricted Cash 6 15
Total Risk Management Assets 43 35
Total Assets 49 50
Liabilities:    
Total Risk Management Liabilities 12 11
Commodity    
Assets:    
Total Risk Management Assets 740 513
Liabilities:    
Total Risk Management Liabilities 386 274
Commodity | AEP Texas    
Assets:    
Total Risk Management Assets 0  
Commodity | APCo    
Assets:    
Total Risk Management Assets 188 82
Liabilities:    
Total Risk Management Liabilities 18 3
Commodity | I&M    
Assets:    
Total Risk Management Assets 26 10
Liabilities:    
Total Risk Management Liabilities 1 0
Commodity | OPCo    
Assets:    
Total Risk Management Assets 0  
Liabilities:    
Total Risk Management Liabilities 22 33
Commodity | PSO    
Assets:    
Total Risk Management Assets 41 42
Liabilities:    
Total Risk Management Liabilities 34 28
Commodity | SWEPCo    
Assets:    
Total Risk Management Assets 43 35
Liabilities:    
Total Risk Management Liabilities 12 11
Commodity Contract, Cash Flow Hedging    
Assets:    
Total Risk Management Assets 114 104
Liabilities:    
Total Risk Management Liabilities 7 6
Fair Value Hedge Instruments    
Liabilities:    
Total Risk Management Liabilities 30 30
Other    
Assets:    
Restricted Cash 14 23
Total Other Temporary Investments and Restricted Cash 29 36
Risk management asset, offset (1,361) (727)
Total Spent Nuclear Fuel and Decommissioning Trusts 17 15
Assets including netting (1,315) (676)
Liabilities:    
Risk management liabilities, offset (1,252) (647)
Other | AEP Texas    
Assets:    
Restricted Cash 0 0
Risk management asset, offset (2)  
Other | APCo    
Assets:    
Restricted Cash 0 0
Risk management asset, offset (2) (2)
Other | I&M    
Assets:    
Total Spent Nuclear Fuel and Decommissioning Trusts 17 15
Assets including netting (1) 4
Other | SWEPCo    
Assets:    
Restricted Cash 0 0
Risk management asset, offset (1) (2)
Other | Commodity    
Assets:    
Risk management asset, offset (1,345) (713)
Liabilities:    
Risk management liabilities, offset (1,236) (633)
Other | Commodity | AEP Texas    
Assets:    
Risk management asset, offset (2)  
Other | Commodity | APCo    
Assets:    
Risk management asset, offset (2) (2)
Liabilities:    
Risk management liabilities, offset (1) (3)
Other | Commodity | I&M    
Assets:    
Risk management asset, offset (18) (11)
Liabilities:    
Risk management liabilities, offset (25) (11)
Other | Commodity | OPCo    
Assets:    
Risk management asset, offset (1)  
Liabilities:    
Risk management liabilities, offset 0 0
Other | Commodity | PSO    
Assets:    
Risk management asset, offset (1) (2)
Liabilities:    
Risk management liabilities, offset 0 (2)
Other | Commodity | SWEPCo    
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 (16) (14)
Liabilities:    
Risk management liabilities, offset (16) (14)
Other | Fair Value Hedge Instruments    
Liabilities:    
Risk management liabilities, offset 0 0
Mutual Funds    
Assets:    
Fixed Income Securities: 191 165
Equity securities, fair value disclosure 46 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: 1,823 1,727
Subtotal Fixed Income Securities | I&M    
Assets:    
Fixed Income Securities: 1,823 1,727
Subtotal Fixed Income Securities | Other    
Assets:    
Fixed Income Securities: 0 0
Subtotal Fixed Income Securities | Other | I&M    
Assets:    
Fixed Income Securities: 0 0
United States Government    
Assets:    
Fixed Income Securities: 1,440 1,351
United States Government | I&M    
Assets:    
Fixed Income Securities: 1,440 1,351
United States Government | Other    
Assets:    
Fixed Income Securities: 0 0
United States Government | Other | I&M    
Assets:    
Fixed Income Securities: 0 0
Corporate Debt    
Assets:    
Fixed Income Securities: 383 376
Corporate Debt | I&M    
Assets:    
Fixed Income Securities: 383 376
Corporate Debt | Other    
Assets:    
Fixed Income Securities: 0 0
Corporate Debt | Other | I&M    
Assets:    
Fixed Income Securities: 0 0
Equity Securities - Domestic    
Assets:    
Equity securities, fair value disclosure 3,398 3,160
Equity Securities - Domestic | I&M    
Assets:    
Equity securities, fair value disclosure 3,398 3,160
Equity Securities - Domestic | Other    
Assets:    
Equity securities, fair value disclosure 0 0
Equity Securities - Domestic | Other | I&M    
Assets:    
Equity securities, fair value disclosure 0 0
Other Cash Deposits    
Assets:    
Cash and cash equivalents, fair value disclosure 15 13
Other Cash Deposits | Other    
Assets:    
Cash and cash equivalents, fair value disclosure 15 13
Cash and Cash Equivalents    
Assets:    
Cash and cash equivalents, fair value disclosure 35 29
Cash and Cash Equivalents | I&M    
Assets:    
Cash and cash equivalents, fair value disclosure 35 29
Cash and Cash Equivalents | Other    
Assets:    
Cash and cash equivalents, fair value disclosure 17 15
Cash and Cash Equivalents | Other | I&M    
Assets:    
Cash and cash equivalents, fair value disclosure 17 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 3  
Level 1 | Estimate of Fair Value Measurement    
Assets:    
Restricted Cash 75 48
Total Other Temporary Investments and Restricted Cash 312 255
Risk Management Assets 10 2
Total Spent Nuclear Fuel and Decommissioning Trusts 3,416 3,174
Total Assets 3,738 3,431
Liabilities:    
Risk Management Liabilities 5 4
Level 1 | Estimate of Fair Value Measurement | AEP Texas    
Assets:    
Restricted Cash 9 14
Total Assets 9  
Level 1 | Estimate of Fair Value Measurement | APCo    
Assets:    
Restricted Cash 60 18
Total Assets 60 18
Level 1 | Estimate of Fair Value Measurement | I&M    
Assets:    
Total Spent Nuclear Fuel and Decommissioning Trusts 3,416 3,174
Total Assets 3,416 3,174
Level 1 | Estimate of Fair Value Measurement | SWEPCo    
Assets:    
Restricted Cash 6 15
Total Assets 6 15
Level 1 | Estimate of Fair Value Measurement | Commodity    
Assets:    
Risk Management Assets 10 2
Liabilities:    
Risk Management Liabilities 5 4
Level 1 | Estimate of Fair Value Measurement | Commodity | AEP Texas    
Assets:    
Risk Management Assets 0  
Level 1 | Estimate of Fair Value Measurement | Commodity | APCo    
Assets:    
Risk Management Assets 0 0
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Commodity | I&M    
Assets:    
Risk Management Assets 0 0
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Commodity | OPCo    
Assets:    
Risk Management Assets 0  
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Commodity | PSO    
Assets:    
Risk Management Assets 0 0
Liabilities:    
Risk Management Liabilities 0 0
Level 1 | Estimate of Fair Value Measurement | Commodity | SWEPCo    
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: 191 165
Equity securities, fair value disclosure 46 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 | I&M    
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 | I&M    
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 | I&M    
Assets:    
Fixed Income Securities: 0 0
Level 1 | Equity Securities - Domestic | Estimate of Fair Value Measurement    
Assets:    
Equity securities, fair value disclosure 3,398 3,160
Level 1 | Equity Securities - Domestic | Estimate of Fair Value Measurement | I&M    
Assets:    
Equity securities, fair value disclosure 3,398 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 18 14
Level 1 | Cash and Cash Equivalents | Estimate of Fair Value Measurement | I&M    
Assets:    
Cash and cash equivalents, fair value disclosure 18 14
Level 2 | Within Current Year    
Liabilities:    
Maturities of net fair value of risk management contracts (5) 12
Level 2 | Maturity Period 2    
Liabilities:    
Maturities of net fair value of risk management contracts 107 65
Level 2 | Maturity Period 3    
Liabilities:    
Maturities of net fair value of risk management contracts 2 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 1,630 931
Total Spent Nuclear Fuel and Decommissioning Trusts 1,823 1,727
Total Assets 3,453 2,658
Liabilities:    
Risk Management Liabilities 1,468 801
Level 2 | Estimate of Fair Value Measurement | AEP Texas    
Assets:    
Restricted Cash 0 0
Total Assets 2  
Level 2 | Estimate of Fair Value Measurement | APCo    
Assets:    
Restricted Cash 0 0
Total Assets 7 3
Level 2 | Estimate of Fair Value Measurement | I&M    
Assets:    
Total Spent Nuclear Fuel and Decommissioning Trusts 1,823 1,727
Total Assets 1,839 1,739
Level 2 | Estimate of Fair Value Measurement | SWEPCo    
Assets:    
Restricted Cash 0 0
Total Assets 1 0
Level 2 | Estimate of Fair Value Measurement | Commodity    
Assets:    
Risk Management Assets 1,519 831
Liabilities:    
Risk Management Liabilities 1,415 752
Level 2 | Estimate of Fair Value Measurement | Commodity | AEP Texas    
Assets:    
Risk Management Assets 2  
Level 2 | Estimate of Fair Value Measurement | Commodity | APCo    
Assets:    
Risk Management Assets 7 3
Liabilities:    
Risk Management Liabilities 19 6
Level 2 | Estimate of Fair Value Measurement | Commodity | I&M    
Assets:    
Risk Management Assets 16 12
Liabilities:    
Risk Management Liabilities 21 11
Level 2 | Estimate of Fair Value Measurement | Commodity | OPCo    
Assets:    
Risk Management Assets 1  
Liabilities:    
Risk Management Liabilities 0 0
Level 2 | Estimate of Fair Value Measurement | Commodity | PSO    
Assets:    
Risk Management Assets 1 1
Liabilities:    
Risk Management Liabilities 34 28
Level 2 | Estimate of Fair Value Measurement | Commodity | SWEPCo    
Assets:    
Risk Management Assets 1 0
Liabilities:    
Risk Management Liabilities 12 11
Level 2 | Estimate of Fair Value Measurement | Commodity Contract, Cash Flow Hedging    
Assets:    
Risk Management Assets 111 100
Liabilities:    
Risk Management Liabilities 23 19
Level 2 | Estimate of Fair Value Measurement | Fair Value Hedge Instruments    
Liabilities:    
Risk Management Liabilities 30 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: 1,823 1,727
Level 2 | Subtotal Fixed Income Securities | Estimate of Fair Value Measurement | I&M    
Assets:    
Fixed Income Securities: 1,823 1,727
Level 2 | United States Government | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 1,440 1,351
Level 2 | United States Government | Estimate of Fair Value Measurement | I&M    
Assets:    
Fixed Income Securities: 1,440 1,351
Level 2 | Corporate Debt | Estimate of Fair Value Measurement    
Assets:    
Fixed Income Securities: 383 376
Level 2 | Corporate Debt | Estimate of Fair Value Measurement | I&M    
Assets:    
Fixed Income Securities: 383 376
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 | I&M    
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 | I&M    
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 119 210
Level 3 | Maturity Period 2    
Liabilities:    
Maturities of net fair value of risk management contracts 251 51
Level 3 | Maturity Period 3    
Liabilities:    
Maturities of net fair value of risk management contracts (2) (6)
Level 3 | Maturity Period 4    
Liabilities:    
Maturities of net fair value of risk management contracts (13) (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 575 411
Total Spent Nuclear Fuel and Decommissioning Trusts 0 0
Total Assets 575 411
Liabilities:    
Risk Management Liabilities 202 152
Level 3 | Estimate of Fair Value Measurement | AEP Texas    
Assets:    
Restricted Cash 0 0
Total Assets 0  
Level 3 | Estimate of Fair Value Measurement | APCo    
Assets:    
Restricted Cash 0 0
Total Assets 183 81
Level 3 | Estimate of Fair Value Measurement | I&M    
Assets:    
Total Spent Nuclear Fuel and Decommissioning Trusts 0 0
Total Assets 28 9
Level 3 | Estimate of Fair Value Measurement | SWEPCo    
Assets:    
Restricted Cash 0 0
Total Assets 43 37
Level 3 | Estimate of Fair Value Measurement | Commodity    
Assets:    
Risk Management Assets 556 393
Liabilities:    
Risk Management Liabilities 202 151
Level 3 | Estimate of Fair Value Measurement | Commodity | AEP Texas    
Assets:    
Risk Management Assets 0  
Level 3 | Estimate of Fair Value Measurement | Commodity | APCo    
Assets:    
Risk Management Assets 183 81
Liabilities:    
Risk Management Liabilities 0 0
Level 3 | Estimate of Fair Value Measurement | Commodity | I&M    
Assets:    
Risk Management Assets 28 9
Liabilities:    
Risk Management Liabilities 5 0
Level 3 | Estimate of Fair Value Measurement | Commodity | OPCo    
Assets:    
Risk Management Assets 0  
Liabilities:    
Risk Management Liabilities 22 33
Level 3 | Estimate of Fair Value Measurement | Commodity | PSO    
Assets:    
Risk Management Assets 41 43
Liabilities:    
Risk Management Liabilities 0 2
Level 3 | Estimate of Fair Value Measurement | Commodity | SWEPCo    
Assets:    
Risk Management Assets 43 37
Liabilities:    
Risk Management Liabilities 0 2
Level 3 | Estimate of Fair Value Measurement | Commodity Contract, Cash Flow Hedging    
Assets:    
Risk Management Assets 19 18
Liabilities:    
Risk Management Liabilities 0 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 | I&M    
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 | I&M    
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 | I&M    
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 | I&M    
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 | I&M    
Assets:    
Cash and cash equivalents, fair value disclosure $ 0 $ 0