Quarterly Financial Data (unaudited) (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
 3 Months Ended 12 Months Ended
Dec. 27, 2014
Sep. 27, 2014
Jun. 28, 2014
Mar. 29, 2014
Dec. 28, 2013
Sep. 28, 2013
Jun. 29, 2013
Mar. 30, 2013
Dec. 29, 2012
Sep. 29, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 27, 2014
Dec. 28, 2013
Dec. 29, 2012
Quarterly Financial Data (unaudited):                              
Net revenues $ 73,746 $ 72,556 $ 71,852 $ 67,509 $ 58,852 $ 54,514 $ 53,667 $ 48,537 $ 43,542 $ 46,601 $ 48,016 $ 47,020 $ 285,663 $ 215,580 $ 185,179
Gross profit 15,176 12,926 13,456 11,563 10,869 10,056 9,136 8,825 8,872 9,471 9,204 9,345 53,121 38,886 36,892
Operating income 5,980 5,356 4,432 3,165 3,074 3,661 2,247 1,868 2,739 2,936 2,825 2,844 18,933 10,850 11,344
Net income $ 3,408 $ 3,084 $ 2,472 $ 1,597 $ 2,007 $ 2,148 $ 1,407 $ 1,056 $ 2,364 $ 1,740 $ 1,623 $ 1,722 $ 10,561 $ 6,618 $ 7,449
Earnings per common share:                              
Basic (in dollars per share) $ 0.17 $ 0.16 $ 0.13 $ 0.08 $ 0.10 $ 0.11 $ 0.07 $ 0.05 $ 0.12 $ 0.09 $ 0.09 $ 0.09 $ 0.54 $ 0.34 $ 0.40
Diluted (in dollars per share) $ 0.17 $ 0.15 $ 0.12 $ 0.08 $ 0.10 $ 0.11 $ 0.07 $ 0.05 $ 0.12 $ 0.09 $ 0.08 $ 0.09 $ 0.53 $ 0.33 $ 0.38
Weighted average number of common shares:                              
Basic (in shares) 19,564 19,530 19,468 19,437 19,454 19,473 19,307 19,206 19,075 19,031 18,899 18,282 19,500 19,360 18,821
Diluted (in shares) 20,062 20,014 19,960 19,924 19,916 19,843 19,702 19,694 19,684 19,690 19,555 19,365 19,990 19,789 19,574