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, 2022	Dec. 31, 2021	Dec. 31, 2020
Effective Tax Rate Reconciliation [Line Items]
Expected income tax expense at 21%	$ 44,766	$ 87,613	$ 42,785
Nondeductible expenses	4,731	4,090	2,399
State income tax expense - net of Federal impact	2,664	8,201	2,944
Return-to-provision and true-up adjustments	(1,971)	(1,617)	(438)
Valuation allowance	1,569	(4,427)	2,427
Research and development credits	(1,136)	(398)	(1,055)
Other – net	(1,515)	(892)	(216)
Total income tax expense	$ 50,864	$ 93,989	$ 48,833
Effective income tax rate	23.90%	22.50%	24.00%
Foreign
Effective Tax Rate Reconciliation [Line Items]
Foreign income tax rate differential	$ 2,955	$ 3,549	$ 1,465
Canada
Effective Tax Rate Reconciliation [Line Items]
Foreign income tax rate differential	$ (1,199)	$ (2,130)	$ (1,478)