CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 29, 2020	Dec. 29, 2019
Trade receivables, allowance	$ 2,950	$ 1,754
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Treasury stock, shares	1,035	608
Common Class A
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	5,507,220	5,506,030
Common Class B
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	2,428,191	2,428,191