Inventories Inventory Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2019	Dec. 30, 2018	Dec. 31, 2017
Inventory Valuation [Roll Forward]
Balance at beginning of period	$ 7,764	$ 7,769	$ 5,747
Additions charged to expense	4,159	3,146	3,283
Deductions	(4,787)	(3,151)	(1,261)
Balance at end of period	$ 7,136	$ 7,764	$ 7,769