Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2017	Jul. 03, 2016	Jul. 02, 2017	Jul. 03, 2016	Jan. 01, 2017
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Capital lease maintenance commitment	$ 26		$ 26
Total rent expense, net of sublease income	210	$ 206	421	$ 404
Wafer and finished goods inventory
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Outstanding commitment for purchases	1,000		1,000		$ 1,600
Other goods and services
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Total outstanding purchase obligations	$ 693		$ 693