Commitments and contingencies - Income Statement Information (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Lessee, Lease, Description [Line Items] | ||||
| Finance lease, right-of-use-asset amortization | $ 607 | $ 607 | $ 1,214 | $ 1,214 |
| Operating Lease Costs | 289 | 290 | 579 | 577 |
| Total lease cost | 1,398 | 1,415 | 2,800 | 2,830 |
| Income Statement Location [Axis]: us-gaap:OtherNonoperatingIncomeExpense | ||||
| Lessee, Lease, Description [Line Items] | ||||
| Finance lease, right-of-use-asset amortization | 502 | 518 | 1,007 | 1,039 |
| Income Statement Location [Axis]: us-gaap:ResearchAndDevelopmentExpense | ||||
| Lessee, Lease, Description [Line Items] | ||||
| Finance lease, right-of-use-asset amortization | 607 | 607 | 1,214 | 1,214 |
| Operating Lease Costs | 205 | 225 | 420 | 448 |
| Income Statement Location [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense | ||||
| Lessee, Lease, Description [Line Items] | ||||
| Operating Lease Costs | $ 84 | $ 65 | $ 159 | $ 129 |