Components of Inventories (Detail) - USD ($) $ in Thousands	Dec. 30, 2017	Dec. 31, 2016
Current inventory:
Raw materials	$ 33,086	$ 35,314
Work in process	6,826	8,131
Finished goods	10,739	9,054
Total current inventory	50,651	52,499
Long term inventory	9,905	6,316
Total inventory	$ 60,556	$ 58,815