| Disaggregation of Revenue [Table Text Block] |
| | | Electricity | | | Natural Gas | | | Other | | | Total | |
| | | (in thousands) | |
| Three Months Ended June 30, 2026 | | | | | | | | | | | | | | | | |
| Fixed rate | | $ | 45,507 | | | $ | 2,813 | | | $ | — | | | $ | 48,320 | |
| Variable rate | | | 38,043 | | | | 7,768 | | | | — | | | | 45,811 | |
| Other | | | — | | | | — | | | | 6,268 | | | | 6,268 | |
| Total | | $ | 83,550 | | | $ | 10,581 | | | $ | 6,268 | | | $ | 100,399 | |
| | | | | | | | | | | | | | | | | |
| Three Months Ended June 30, 2025 | | | | | | | | | | | | | | | | |
| Fixed rate | | $ | 55,400 | | | $ | 2,653 | | | $ | — | | | $ | 58,053 | |
| Variable rate | | | 34,485 | | | | 6,454 | | | | — | | | | 40,939 | |
| Other | | | — | | | | — | | | | 6,259 | | | | 6,259 | |
| Total | | $ | 89,885 | | | $ | 9,107 | | | $ | 6,259 | | | $ | 105,251 | |
| | | | | | | | | | | | | | | | | |
| Six Months Ended June 30, 2026 | | | | | | | | | | | | | | | | |
| Fixed rate | | $ | 93,153 | | | $ | 7,576 | | | $ | — | | | $ | 100,729 | |
| Variable rate | | | 89,809 | | | | 38,356 | | | | — | | | | 128,165 | |
| Other | | | — | | | | — | | | | 13,817 | | | | 13,817 | |
| Total | | $ | 182,962 | | | $ | 45,932 | | | $ | 13,817 | | | $ | 242,711 | |
| | | | | | | | | | | | | | | | | |
| Six Months Ended June 30, 2025 | | | | | | | | | | | | | | | | |
| Fixed rate | | $ | 114,304 | | | $ | 9,583 | | | $ | — | | | $ | 123,887 | |
| Variable rate | | | 79,644 | | | | 27,933 | | | | — | | | | 107,577 | |
| Other | | | — | | | | — | | | | 10,594 | | | | 10,594 | |
| Total | | $ | 193,948 | | | $ | 37,516 | | | $ | 10,594 | | | $ | 242,058 | |
| | | Electricity | | | Natural Gas | | | Other | | | Total | |
| | | (in thousands) | |
| Three Months Ended June 30, 2026 | | | | | | | | | | | | | | | | |
| Non-Commercial Channel | | $ | 78,925 | | | $ | 7,671 | | | $ | — | | | $ | 86,596 | |
| Commercial Channel | | | 4,625 | | | | 2,910 | | | | — | | | | 7,535 | |
| Other | | | — | | | | — | | | | 6,268 | | | | 6,268 | |
| Total | | $ | 83,550 | | | $ | 10,581 | | | $ | 6,268 | | | $ | 100,399 | |
| | | | | | | | | | | | | | | | | |
| Three Months Ended June 30, 2025 | | | | | | | | | | | | | | | | |
| Non-Commercial Channel | | $ | 74,251 | | | $ | 6,488 | | | $ | — | | | $ | 80,739 | |
| Commercial Channel | | | 15,634 | | | | 2,619 | | | | — | | | | 18,253 | |
| Other | | | — | | | | — | | | | 6,259 | | | | 6,259 | |
| Total | | $ | 89,885 | | | $ | 9,107 | | | $ | 6,259 | | | $ | 105,251 | |
| | | | | | | | | | | | | | | | | |
| Six Months Ended June 30, 2026 | | | | | | | | | | | | | | | | |
| Non-Commercial Channel | | $ | 172,698 | | | $ | 38,619 | | | $ | — | | | $ | 211,317 | |
| Commercial Channel | | | 10,264 | | | | 7,313 | | | | — | | | | 17,577 | |
| Other | | | — | | | | — | | | | 13,817 | | | | 13,817 | |
| Total | | $ | 182,962 | | | $ | 45,932 | | | $ | 13,817 | | | $ | 242,711 | |
| | | | | | | | | | | | | | | | | |
| Six Months Ended June 30, 2025 | | | | | | | | | | | | | | | | |
| Non-Commercial Channel | | $ | 161,134 | | | $ | 29,862 | | | $ | — | | | $ | 190,996 | |
| Commercial Channel | | | 32,814 | | | | 7,654 | | | | — | | | | 40,468 | |
| Other | | | — | | | | — | | | | 10,594 | | | | 10,594 | |
| Total | | $ | 193,948 | | | $ | 37,516 | | | $ | 10,594 | | | $ | 242,058 | |
|