Other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Before-Tax Amount
Other comprehensive loss	$ (16,358)	$ (30,095)	$ (9,072)	$ (80,086)
Tax Expense (Benefit)
Other comprehensive loss	(3,063)	(5,489)	(1,794)	(15,025)
Net-of-Tax Amount
Other comprehensive loss, net of taxes:	(13,295)	(24,606)	(7,278)	(65,061)
Net unrealized gains and losses on investments
Before-Tax Amount
Change in net unrealized gains and losses on investments	(9,452)	(11,292)	(8,374)	(52,548)
Reclassification adjustments for realized gains and losses on investments	25	(488)	421	(870)
Other comprehensive loss	(9,427)	(11,780)	(7,953)	(53,418)
Tax Expense (Benefit)
Change in net unrealized gains and losses on investments	(1,984)	(2,371)	(1,758)	(11,035)
Reclassification adjustments for realized gains and losses on investments	5	(103)	88	(183)
Other comprehensive loss	(1,979)	(2,474)	(1,670)	(11,218)
Net-of-Tax Amount
Change in net unrealized gains and losses on investments	(7,468)	(8,921)	(6,616)	(41,513)
Reclassification adjustments for realized gains and losses on investments	20	(385)	333	(687)
Other comprehensive loss, net of taxes:	(7,448)	(9,306)	(6,283)	(42,200)
Foreign currency translation adjustments
Before-Tax Amount
Other comprehensive loss	(6,931)	(18,315)	(1,119)	(26,668)
Tax Expense (Benefit)
Other comprehensive loss	(1,084)	(3,015)	(124)	(3,807)
Net-of-Tax Amount
Other comprehensive loss, net of taxes:	$ (5,847)	$ (15,300)	$ (995)	$ (22,861)