Earnings per share - Summary of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Basic weighted average number of shares outstanding	12,467,632	12,579,130
Net dilutive effect of share-based awards, treasury method	1,031,702	720,113
Diluted weighted average number of shares outstanding	13,499,334	13,299,243
Net income	$ 9,292	$ 38,658
Basic (in dollars per share)	$ 0.75	$ 3.07
Diluted (in dollars per share)	$ 0.69	$ 2.91