CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 25, 2017	Dec. 25, 2016
Trade receivables, allowance	$ 2,692	$ 3,254
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Treasury stock, shares	25,776	34
Common Class A
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	5,205,318	5,132,417
Common Class B
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	2,443,191	2,443,191