Other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Before-Tax Amount
Other comprehensive loss	$ (24,446)	$ (9,422)
Tax Expense (Benefit)
Other comprehensive loss	(4,983)	(1,988)
Net-of-Tax Amount
Other comprehensive loss	(19,463)	(7,434)
Net unrealized gains and losses on investments
Before-Tax Amount
Change in net unrealized gains and losses on investments	(25,188)	(11,589)
Reclassification adjustments for realized gains and losses on investments	(234)	(184)
Other comprehensive loss	(25,422)	(11,773)
Tax Expense (Benefit)
Change in net unrealized gains and losses on investments	(5,290)	(2,433)
Reclassification adjustments for realized gains and losses on investments	(49)	(39)
Other comprehensive loss	(5,339)	(2,472)
Net-of-Tax Amount
Change in net unrealized gains and losses on investments	(19,898)	(9,156)
Reclassification adjustments for realized gains and losses on investments	(185)	(145)
Other comprehensive loss	(20,083)	(9,301)
Foreign currency translation adjustments
Before-Tax Amount
Other comprehensive loss	976	2,351
Tax Expense (Benefit)
Other comprehensive loss	356	484
Net-of-Tax Amount
Other comprehensive loss	$ 620	$ 1,867