Stock based awards - performance based awards (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount
Options granted ( in shares)	1,648,855
Weighted-average exercise price, Granted (in dollars per share)	$ 22.29
Total stock-based compensation expense	$ 10,054	$ 6,022	$ 1,770
Performance Shares [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount
Options granted ( in shares)	610,546
Weighted-average exercise price, Granted (in dollars per share)	$ 21.10