Business Segments - Revenue Information by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	$ 10,483	$ 11,931
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	5,704	5,848
Europe
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	1,935	2,291
Rest of Americas
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	609	620
Asia/Pacific Rim
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	$ 2,235	$ 3,172