(10) Concentrations of Credit Risk Significant Customers and Geographic Information (Details)	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Percent of Total Revenues Country
United States of America	30.00%	29.00%	21.00%
Germany	42.00%	38.00%	50.00%
Other	28.00%	33.00%	29.00%