REGULATORY ASSETS AND LIABILITIES - Additional Information (Details) - CAD ($) $ in Millions |
1 Months Ended | 12 Months Ended | |
|---|---|---|---|
Mar. 31, 2019 |
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Regulatory Matters [Line Items] | |||
| Earnings sharing percentage excess return on equity | 50.00% | ||
| Return on equity excess threshold basis points | 1.00% | ||
| Return on equity threshold basis points regulated acquired utilities | 3.00% | ||
| Polychlorinated Biphenyl Liability | |||
| Regulatory Matters [Line Items] | |||
| Increase (decrease) to regulatory assets | $ 2 | $ 2 | |
| Rural and remote rate protection (RRRP) variance | Hydro One Remote Communities | |||
| Regulatory Matters [Line Items] | |||
| Increase (decrease) to regulatory assets | $ (24) | $ (12) | |