Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Payroll and related items	$ 73,121		$ 75,869
Management incentive compensation	18,962		24,320
Income taxes payable	25,753		28,033
Insurance	9,929		9,424
Warranty	5,852		6,281
Deferred revenue	10,271	$ 11,031	11,031
Restructuring	6,391		4,180
Liability for uncertain tax positions	1,296		1,745
Accrued interest	10,443		1,759
Other	23,435		22,063
Total accrued expenses	$ 185,453		$ 184,705