Liability for loss and loss adjustment expenses - Summary of Liability for Loss and Loss Adjustment Expenses (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]    
Balance at the beginning of the year $ 80,267 $ 69,800
Provision for claims related to:    
Current year 5,656 6,490
Prior years (1,045) (3,241)
Total provision for claims 4,611 3,249
Paid losses related to:    
Current year (548) (222)
Prior years (1,796) (2,176)
Total paid losses (2,344) (2,398)
Balance at the end of the period $ 82,534 $ 70,651
Premiums Written, Net | Provision for Incurred Claims Concentration Risk | Liability for Unpaid Claims and Claims Adjustment Expense, Net    
Paid losses related to:    
Concentration risk percent 4.80% 3.00%