Geographic and Group Information (Long-Lived Assets Attributable To Geographic Area) (Details) - USD ($) $ in Thousands	Jun. 29, 2018	Dec. 29, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	$ 112,591	$ 109,946
North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	92,990	90,605
International (Primarily European Countries) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	$ 19,601	$ 19,341