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. 29, 2018	Dec. 30, 2017
Tax effect of temporary differences and carryforwards that give rise to significant portions of the net deferred tax assets
Net operating losses	$ 8,195	$ 5,757
Research and development credits	3,048	2,839
Accruals and reserves	2,357	2,031
Deferred revenue	304	341
Property and equipment	314	314
Intangible assets	452	495
Stock compensation	797	528
Other tax credits	1	1
Net deferred tax asset	15,468	12,306
Valuation allowance	(15,485)	(12,320)
Net deferred tax liabilities	$ (17)	$ (14)