Balance Sheet Classification of Warranty Provision Account (Detail) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 29, 2018	Mar. 31, 2018	Dec. 31, 2017
Product Warranty Liability [Line Items]
Other accrued liabilities	$ 1,147	$ 839
Other long-term liabilities	150	158
Total warranty provision	$ 1,297	$ 997	$ 866	$ 994