Income taxes - Schedule of Reconciliation of Effective Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Amount
U.S. federal statutory income tax	$ 9,806	$ 9,497	$ 47,176
U.S. state and local income taxes, net of U.S. federal income tax benefits	4,150	3,110	13,585
Unrecognized tax benefit	45	180	59
Valuation allowance	964	1,054	1,121
Non-taxable income	(964)	(1,083)	(430)
Provision to return adjustments	(812)	(316)	281
Change in state and foreign tax rates	(514)	(660)	1,384
Foreign tax rate differentials	(146)	(285)	(223)
Excess tax benefits from share-based awards	(1,378)	(471)	(1,542)
Non-deductible executive compensation	1,514	1,605	3,956
Other non-deductible expenses	3,833	813	310
Total income taxes	$ 16,498	$ 13,444	$ 65,677
Percentage
U.S. federal statutory income tax rate (as a percent)	21.00%	21.00%	21.00%
U.S. state and local income taxes, net of U.S. federal income tax benefits (as a percent)	8.90%	6.80%	6.00%
Unrecognized tax benefits (as a percent)	0.10%	0.40%	0.00%
Valuation allowance (as a percent)	2.10%	2.30%	0.50%
Non-taxable income (as a percent)	(2.10%)	(2.40%)	(0.20%)
Provision to return adjustments (as a percent)	(1.70%)	(0.70%)	0.10%
Change in state and foreign tax rates (as a percent)	(1.10%)	(1.40%)	0.60%
Foreign tax rate differentials (as a percent)	(0.30%)	(0.60%)	(0.10%)
Excess tax benefits from share-based awards (as a percent)	(2.90%)	(1.00%)	(0.70%)
Non-Deductible Executive Compensation (as a percent)	3.20%	3.50%	1.80%
Other non-deductible expenses (as a percent)	8.10%	1.60%	0.20%
Total income tax expense (as a percent)	35.30%	29.50%	29.20%