Business Segments and Significant Customers (Details) (USD $)
In Thousands, 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
Business segments and significant customers                              
Total net revenue $ 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
Sales Revenue, Goods, Net [Member] | Customer Concentration Risk [Member] | Costco [Member]                              
Business segments and significant customers                              
Total net revenue                         $ 75,300 $ 74,500 $ 64,600
Concentration risk (as a percent)                         26.00% 35.00% 35.00%