Income Taxes - Tax Effect of Temporary Differences and Carryforwards that Give Rise to Significant Portions of the Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 30, 2017	Dec. 31, 2016
Tax effect of temporary differences and carryforwards that give rise to significant portions of the net deferred tax assets
Net operating losses	$ 5,757	$ 4,411
Research and development credits	2,839	2,113
Accruals and reserves	2,031	2,158
Deferred revenue	341	104
Property and equipment	314	396
Intangible assets	495	783
Stock compensation	528	972
Other tax credits	1	90
Net deferred tax asset	12,306	11,027
Valuation allowance	(12,320)	(11,095)
Net deferred tax liabilities	$ (14)	$ (68)