Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 30, 2017
Consolidated Balance Sheets [Abstract]
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	100,800,000	100,800,000
Common stock, shares issued	33,047,807	33,047,807
Common stock, shares outstanding	26,898,443	26,898,443
Accumulated other comprehensive income, deferred taxes	$ 1	$ 2,310
Treasury stock, shares	6,149,364	6,149,364