Retirement Plans - Schedule of Costs of Retirement Plans (Details) - Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Contribution Plan Disclosure
Expenses associated with contributions made	$ 1,440	$ 2,909	$ 3,406
United States
Defined Contribution Plan Disclosure
Expenses associated with contributions made	866	2,323	2,762
Canada
Defined Contribution Plan Disclosure
Expenses associated with contributions made	137	144	193
United Kingdom
Defined Contribution Plan Disclosure
Expenses associated with contributions made	$ 437	$ 442	$ 451