Income taxes - Reconciliation of Income Tax Expenses Computed at Federal Statutory Rate with Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective Tax Rate Reconciliation [Line Items]
Expected income tax expense at 21%	$ 9,597	$ 44,766	$ 87,613
Valuation allowance	6,222	1,569	(4,427)
Nondeductible expenses	3,140	4,731	4,090
Return-to-provision and true-up adjustments	(2,745)	(1,971)	(1,617)
Research and development credits	(1,096)	(1,136)	(398)
State income tax expense - net of Federal impact	156	2,664	8,201
Other – net	(412)	(1,515)	(892)
Total income tax expense	$ 15,263	$ 50,864	$ 93,989
Effective income tax rate	33.40%	23.90%	22.50%
Foreign
Effective Tax Rate Reconciliation [Line Items]
Foreign income tax rate differential	$ 2,778	$ 2,955	$ 3,549
Canada
Effective Tax Rate Reconciliation [Line Items]
Foreign income tax rate differential	$ (2,377)	$ (1,199)	$ (2,130)