Cash And Cash Equivalents And Advertising Accounting Policies (Effect Of Reclassification Of Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 30, 2017	Jul. 01, 2017	Dec. 31, 2016
Cash and cash equivalents	$ 34,623	$ 47,917	$ 43,689	$ 46,818
Accounts receivable, net	$ 52,835	56,265
As Previously Reported [Member]
Cash and cash equivalents		21,305	17,582	14,653
Accounts receivable, net		82,877
Reclassifications [Member]
Cash and cash equivalents		26,612	$ 26,107	$ 32,165
Accounts receivable, net		$ (26,612)