Business Segments - Reportable Segments Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 24, 2016 USD ($)	Sep. 30, 2017 segment	Sep. 30, 2017 item	Sep. 30, 2017 USD ($)	Sep. 24, 2016 USD ($)
Business segments revenue by products
Number of reportable segments			2	2
Net revenues from external customers	$ 27,428	$ 28,587			$ 84,248	$ 80,956
Healthy And Natural Food Product
Business segments revenue by products
Net revenues from external customers	18,400	19,400			56,200	52,000
Healthy Natural Snacks Product
Business segments revenue by products
Net revenues from external customers	$ 9,000	$ 9,200			$ 28,100	$ 29,000