Retirement Plans - Schedule of Costs of Retirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Contribution Plan Disclosure
Expenses associated with contributions made	$ 564	$ 482	$ 1,677	$ 972
United States
Defined Contribution Plan Disclosure
Expenses associated with contributions made	400	346	1,172	558
Canada
Defined Contribution Plan Disclosure
Expenses associated with contributions made	33	25	119	93
United Kingdom
Defined Contribution Plan Disclosure
Expenses associated with contributions made	$ 131	$ 111	$ 386	$ 321