Other comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Before-Tax Amount
Other comprehensive income	$ (9,422)	$ (17,027)
Tax Expense (Benefit)
Other comprehensive loss	(1,988)	(2,925)
Net-of-Tax Amount
Other comprehensive loss, net of taxes:	(7,434)	(14,102)
Net unrealized gains and losses on investments
Before-Tax Amount
Change in net unrealized gains and losses on investments	(11,589)	(3,267)
Reclassification adjustment for realized gains and losses on investments	(184)	(101)
Other comprehensive income	(11,773)	(3,368)
Tax Expense (Benefit)
Change in net unrealized gains and losses on investments	(2,433)	(687)
Reclassification adjustment for realized gains and losses on investments	(39)	(21)
Other comprehensive loss	(2,472)	(708)
Net-of-Tax Amount
Change in net unrealized gains and losses on investments	(9,156)	(2,580)
Reclassification adjustment for realized gains and losses on investments	(145)	(80)
Other comprehensive loss, net of taxes:	(9,301)	(2,660)
Foreign currency translation adjustments
Before-Tax Amount
Other comprehensive income	2,351	(13,659)
Tax Expense (Benefit)
Other comprehensive loss	484	(2,217)
Net-of-Tax Amount
Other comprehensive loss, net of taxes:	$ 1,867	$ (11,442)