Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Payroll and benefits	$ 143,383	$ 115,693
Short-term operating lease liability	49,748	40,972
Deferred revenue and customer advances	30,269	16,177
Income taxes payable	26,602	11,661
Short-term finance lease liability	12,634	9,121
Accrued severance plan obligations (Note 12)	10,837	13,408
Accrued interest	10,767	11,638
Other accrued expenses	64,967	48,556
Total accrued expenses	$ 349,207	$ 267,226
Operating lease, liability, current, statement of financial position	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent