Difference Between Tax Provision (Benefit) at Statutory Federal Income Tax Rate and Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Reconciliation Of Income Taxes [Line Items]
Income tax (benefit) at the federal statutory rate	$ 1,827	$ (2,517)	$ (3,014)
State income taxes, net of federal benefit	13	5	6
Effect of foreign operations taxed at various rates	(1,036)	(232)	(140)
Research tax credits	(2,267)	(1,058)	(931)
Change in federal tax rate	9,201
Effect of tax rate changes, permanent differences and adjustments of prior deferrals	639	1,137	2,114
Unrecognized tax benefits	202	(281)	264
Total	1,103	251	555
United States
Reconciliation Of Income Taxes [Line Items]
Change in valuation allowance	(6,873)	3,333	1,625
Foreign Tax Authority
Reconciliation Of Income Taxes [Line Items]
Change in valuation allowance	$ (603)	$ (136)	$ 631