REGULATORY ASSETS AND LIABILITIES - REGULATORY LIABILITIES (Details) - USD ($) $ in Millions |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Regulatory liabilities | ||
| Other current liabilities | $ 10.6 | $ 15.6 |
| Regulatory liabilities | 1,824.8 | 1,759.0 |
| Total regulatory liabilities | 1,835.4 | 1,774.6 |
| Removal costs | ||
| Regulatory liabilities | ||
| Total regulatory liabilities | 892.9 | 862.1 |
| Income tax related items | ||
| Regulatory liabilities | ||
| Total regulatory liabilities | 652.8 | 663.5 |
| Pension and OPEB benefits | ||
| Regulatory liabilities | ||
| Total regulatory liabilities | 112.5 | 114.6 |
| Energy costs refundable through rate adjustments | ||
| Regulatory liabilities | ||
| Total regulatory liabilities | 71.9 | 47.2 |
| Earnings sharing mechanisms | ||
| Regulatory liabilities | ||
| Total regulatory liabilities | 27.7 | 29.3 |
| We Power escrowed costs | ||
| Regulatory liabilities | ||
| Total regulatory liabilities | 16.5 | 15.1 |
| Derivatives | ||
| Regulatory liabilities | ||
| Total regulatory liabilities | 14.7 | 6.8 |
| Other, net | ||
| Regulatory liabilities | ||
| Total regulatory liabilities | $ 46.4 | $ 36.0 |