Note 1 - Summary of Significant Accounting Policies - Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 30, 2017
Raw materials and purchased parts	$ 27,277	$ 27,918
Work in process	25,267	25,130
Finished goods	10,132	9,037
Total inventories	$ 62,676	$ 62,085	[1]

[1] Derived from December 30, 2017 audited financial statements