Asset Retirement Obligations (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] | ||
| Beginning Balance | $ 100.7 | $ 96.2 |
| Liabilities Incurred | 0.0 | 0.2 |
| Liabilities Settled | 0.0 | 0.0 |
| Accretion | 4.2 | 4.1 |
| Revisions to Prior Estimates | (0.3) | 0.2 |
| Ending Balance | 104.6 | 100.7 |
| Electric Utilities | ||
| Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] | ||
| Beginning Balance | 30.0 | 28.7 |
| Liabilities Incurred | 0.0 | 0.0 |
| Liabilities Settled | 0.0 | 0.0 |
| Accretion | 1.3 | 1.1 |
| Revisions to Prior Estimates | (0.3) | 0.2 |
| Ending Balance | 31.0 | 30.0 |
| Gas Utilities | ||
| Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] | ||
| Beginning Balance | 70.7 | 67.5 |
| Liabilities Incurred | 0.0 | 0.2 |
| Liabilities Settled | 0.0 | 0.0 |
| Accretion | 2.9 | 3.0 |
| Revisions to Prior Estimates | 0.0 | 0.0 |
| Ending Balance | $ 73.6 | $ 70.7 |