| Line Item | Jun 30, 2026 | Mar 31, 2026 | Dec 31, 2025 | Sep 30, 2025 | Jun 30, 2025 | Mar 31, 2025 | Dec 31, 2024 | Sep 30, 2024 | Jun 30, 2024 | Mar 31, 2024 | Dec 31, 2023 | Sep 30, 2023 | Jun 30, 2023 | Mar 31, 2023 | Dec 31, 2022 | Sep 30, 2022 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Operating revenues | ||||||||||||||||
| YoY growth | +3.1% | +10.0% | +15.7% | +9.6% | ||||||||||||
| Operating expenses: | ||||||||||||||||
| Operations and maintenance | ||||||||||||||||
| Purchased gas | ||||||||||||||||
| Depreciation Expense | ||||||||||||||||
| Goodwill Impairment | ||||||||||||||||
| Taxes other than income taxes | ||||||||||||||||
| Total operating expenses | ||||||||||||||||
| % of revenue | 63.6% | 64.0% | 67.5% | 64.4% | ||||||||||||
| Operating income | ||||||||||||||||
| % of revenue | 36.4% | 36.0% | 32.5% | 35.6% | ||||||||||||
| Other expense (income): | ||||||||||||||||
| Interest expense | ||||||||||||||||
| Interest income | ||||||||||||||||
| Allowance for funds used during construction | ||||||||||||||||
| Other, net | ||||||||||||||||
| Income before income taxes | ||||||||||||||||
| Income tax expense (benefit) | ||||||||||||||||
| Net income | ||||||||||||||||
| % of revenue | 19.9% | 26.0% | 19.0% | 19.3% | ||||||||||||
| Basic | ||||||||||||||||
| Diluted |