Commitments and contingencies - Litigation (Details) - USD ($) |
1 Months Ended | |||
|---|---|---|---|---|
Jan. 31, 2026 |
Jun. 30, 2026 |
Dec. 31, 2025 |
Jun. 30, 2025 |
|
| Commitments and Contingencies Disclosure [Abstract] | ||||
| Potential liabilities related to litigation and environmental matters | $ 24,600,000 | $ 26,100,000 | $ 25,000,000.0 | |
| Loss contingency, receivable | 69,000 | 1,600,000 | 1,400,000 | |
| Loss contingency, regulatory asset | $ 22,700,000 | 23,200,000 | $ 22,300,000 | |
| Loss contingency, complaint | $ 2,000,000.0 | |||
| Amount suspended | $ 250,000 | |||
| Loss contingency accrued | $ 1,750,000 |