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Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands | Sep. 30, 2021 | Dec. 31, 2020
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Payables and Accruals [Abstract] |  |
Accrued salaries, wages and related employee benefits | $ 38,470 | $ 30,214
Contingent consideration, current portion | 1,736 | 1,300
Accrued workers’ compensation and health benefits | 3,654 | 3,948
Deferred revenue | 7,143 | 6,538
Pension accrual | 2,519 | 2,519
Right-of-use liability - Operating | 9,871 | 10,348
Other accrued expenses | 24,919 | 23,633
Accrued expenses and other current liabilities | $ 88,312 | $ 78,500

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