Deferred acquisition costs and deferred ceding commissions - Narrative (Details) - USD ($) |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Insurance [Abstract] | ||||
| Ceding commission income, net increase (decrease) | $ 7,100,000 | $ 12,500,000 | $ 7,100,000 | $ 12,500,000 |