Fair value measurements - Schedule of Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair value
Less than 12 months	$ 153,737	$ 143,991
12 months or greater	6,392	603
Total	160,129	144,594
Unrealized losses
Less than 12 months	(561)	(57)
12 months or greater	(6)	0
Total	(567)	(57)
U.S. government agency securities and treasuries
Fair value
Less than 12 months	108,695	105,692
12 months or greater	2,496	0
Total	111,191	105,692
Unrealized losses
Less than 12 months	(505)	(37)
12 months or greater	(4)	0
Total	(509)	(37)
Corporate bonds
Fair value
Less than 12 months	45,042	38,299
12 months or greater	3,896	603
Total	48,938	38,902
Unrealized losses
Less than 12 months	(56)	(20)
12 months or greater	(2)	0
Total	$ (58)	$ (20)