Income taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income taxes
Income before income taxes	$ 117,182	$ 33,399
Income tax expense	13,381	1,140
Deferred tax assets, valuation allowance	15,100	15,149	$ 19,000	$ 19,000	$ 11,300
Net operating loss		16,800
Valuation allowance		3,900
Current year utilization comprise of deferred tax		$ 7,270
Federal
Income taxes
Operating loss carryforwards	0
Current year utilization comprise of deferred tax	29,300
State
Income taxes
Operating loss carryforwards	$ 1,500