| Segment Reporting [Table Text Block] |
| | | Three Months Ended June 30, 2026 | |
| | | Grid | | | Wind | | | Unallocated | | | Total | |
| Segment operating income: | | | | | | | | | | | | | | | | |
| Revenues | | $ | 76,323 | | | $ | 17,750 | | | $ | — | | | $ | 94,073 | |
| | | | | | | | | | | | | | | | | |
| Less (a) | | | | | | | | | | | | | | | | |
| Segment other operating expenses (b) | | | 78,489 | | | | 13,867 | | | | (8,115 | ) | | | 84,241 | |
| Segment operating income (loss) | | $ | (2,166 | ) | | $ | 3,883 | | | $ | 8,115 | | | $ | 9,832 | |
| | | Three Months Ended June 30, 2025 | |
| | | Grid | | | Wind | | | Unallocated | | | Total | |
| Segment operating income: | | | | | | | | | | | | | | | | |
| Revenues | | $ | 60,087 | | | $ | 12,271 | | | $ | — | | | $ | 72,358 | |
| | | | | | | | | | | | | | | | | |
| Less (a) | | | | | | | | | | | | | | | | |
| Segment other operating expenses (b) | | | 55,932 | | | | 10,782 | | | | — | | | | 66,714 | |
| Segment operating income | | $ | 4,155 | | | $ | 1,489 | | | $ | — | | | $ | 5,644 | |
| | | Three Months Ended June 30, | |
| | | 2026 | | | 2025 | |
| | | | | | | | | |
| Operating income: | | $ | 9,832 | | | $ | 5,644 | |
| Interest income, net | | | 1,537 | | | | 932 | |
| Other (expense)/income, net | | | (617 | ) | | | 347 | |
| Income before income tax expense | | $ | 10,752 | | | $ | 6,923 | |
| | | Three Months Ended June 30, | |
| | | 2026 | | | 2025 | |
| | | | | | | | | |
| Grid | | $ | 2,604 | | | $ | 1,202 | |
| Wind | | | 43 | | | | 27 | |
| Total | | $ | 2,647 | | | $ | 1,229 | |
|
| Segment Reporting, Reconciliation of Asset by Segment to Consolidated [Table Text Block] |
| | | June 30, 2026 | | | March 31, 2026 | |
| Grid | | $ | 590,555 | | | $ | 574,195 | |
| Wind | | | 18,416 | | | | 17,572 | |
| Corporate assets | | | 153,246 | | | | 147,714 | |
| Total | | $ | 762,217 | | | $ | 739,481 | |
|