Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 29, 2018	Dec. 31, 2017	Dec. 30, 2017
Disclosure Accrued Expenses [Abstract]
Accrued payroll and related expenses	$ 70,998		$ 67,935
Standard Product Warranty Accrual, Current	59,644		52,834
Accrued warranty	59,644		52,834
Contract with Customer, Liability	69,936	$ 47,647	31,069
Product Liability Contingency, Loss Exposure in Excess of Accrual, High Estimate	5,140		6,068
Accured Restructuring Liabilities, Current	2,679		1,715
Accrued customer rebates	39,465		48,590
Accrued Product Liability And Workers Compensation Liability Current	16,439		11,976
Accrued agent commission	12,809		11,035
Accrued professional services	18,723		18,250
Sales and Excise Tax Payable, Current	15,509		20,881
Other accrued expenses	61,955		51,818
Accrued expenses	$ 373,297		$ 322,171