Summary of Significant Accounting Policies (Allowance for doubtful accounts) (Details) - Allowance for doubtful accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 3,867	$ 1,904	$ 2,140
Adjustments to allowance	508	2,440	846
Amounts written off, net of recoveries and other adjustments	816	477	1,082
Balance at end of period	$ 3,559	$ 3,867	$ 1,904