Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 30, 2017
Allowance for doubtful accounts on accounts receivable	$ 47	$ 0
Common Class A
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	22,700,000	22,700,000
Common Stock, shares issued	8,700,167	8,603,152
Common Stock, shares outstanding	8,700,167	8,603,152
Common Class B
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	4,200,000	4,200,000
Common Stock, shares issued	3,017,983	3,017,983
Common Stock, shares outstanding	3,017,983	3,017,983