Goodwill and Identified Intangible Assets - Amortization Expense for Identifiable Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Included in cost of revenue	$ 1,295	$ 1,295	$ 2,590	$ 2,590
Included in operating expenses	784	800	1,572	1,604
Total amortization expense	$ 2,079	$ 2,095	$ 4,162	$ 4,194