FINANCING ACTIVITIES - Schedule of Accounts Receivable and Accrued Unbilled Revenues (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| APCo | ||
| Short-Term Debt [Line Items] | ||
| Accounts receivable and accrued unbilled revenues | $ 210 | $ 203 |
| I&M | ||
| Short-Term Debt [Line Items] | ||
| Accounts receivable and accrued unbilled revenues | 191 | 175 |
| OPCo | ||
| Short-Term Debt [Line Items] | ||
| Accounts receivable and accrued unbilled revenues | 600 | 501 |
| PSO | ||
| Short-Term Debt [Line Items] | ||
| Accounts receivable and accrued unbilled revenues | 281 | 140 |
| SWEPCo | ||
| Short-Term Debt [Line Items] | ||
| Accounts receivable and accrued unbilled revenues | $ 232 | $ 169 |