Income taxes - Schedule of Reconciliation of Effective Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Effective Income Tax Rate Reconciliation, Amount [Abstract]
U.S. federal statutory income tax	$ 47,176	$ 35,491	$ 15,732
U.S. state and local income taxes, net of U.S. federal income tax benefits	13,585	8,770	4,258
Unrecognized tax benefit	59	(853)	0
Valuation allowance	1,121	517	1,663
Non-taxable income	(430)	(580)	(738)
Provision to return adjustments	281	239	(723)
Change in state and foreign tax rates	1,384	238	(135)
Foreign tax rate differentials	(223)	(469)	(59)
Excess tax benefits from share-based awards	(1,542)	(1,008)	(234)
Non-Deductible Executive Compensation	3,956	2,831	1,072
Other non-deductible expenses	310	838	1,123
Total income taxes	$ 65,677	$ 46,014	$ 21,959
Effective Income Tax Rate Reconciliation, Percent [Abstract]
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)	6.00%	5.20%	5.70%
Unrecognized tax benefits (as a percent)	0.00%	(0.50%)	0.00%
Valuation allowance (as a percent)	0.50%	0.30%	2.20%
Non-taxable income (as a percent)	(0.20%)	(0.30%)	(1.00%)
Provision to return adjustments (as a percent)	0.10%	0.10%	(1.00%)
Change in state and foreign tax rates (as a percent)	0.60%	0.10%	(0.20%)
Foreign tax rate differentials (as a percent)	(0.10%)	(0.30%)	(0.10%)
Excess tax benefits from share-based awards (as a percent)	(0.70%)	(0.60%)	(0.30%)
Non-Deductible Executive Compensation (as a percent)	1.80%	1.70%	1.40%
Other non-deductible expenses (as a percent)	0.20%	0.50%	1.60%
Total income tax expense (as a percent)	29.20%	27.20%	29.30%