Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Trade accounts payable	$ 40,969	$ 24,189
Accrued salaries, vacation and benefits	21,550	22,205
Other accrued expenses	28,372	26,256
Accrued contingent consideration	594	2,724
Negative cash book balance	1,769	2,906
Accounts Payable and Accrued Liabilities, Current, Total	$ 93,254	$ 78,280