Restructuring Costs Expensed (Details) - Realignment of Office Furniture Facilities and Exit of Business Line - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 128	$ 2,335	$ 2,303	$ 12,036
Cost of sales - accelerated depreciation
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	1,552	0	8,711
Restructuring and impairment charges
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 128	$ 783	$ 2,303	$ 3,325