Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued salaries, wages and related employee benefits	$ 30,214	$ 30,072
Contingent consideration	1,300	2,614
Accrued workers' compensation and health benefits	3,948	4,467
Deferred revenues	6,538	5,860
Right-of-use liability - Operating	10,348	10,133
Pension accrual	2,519	2,519
Other accrued expenses	23,633	25,724
Total accrued expenses and other current liabilities	$ 78,500	$ 81,389