Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 30, 2018
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 41	$ 28
Accumulated amortization on other assets	$ 1,837	$ 1,772
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	25,274,685	25,074,307
Common stock, shares outstanding	21,624,472	21,424,094
Treasury stock, shares	3,650,213	3,650,213