Goodwill and Identified Intangible Assets - Amortization Expense for Identifiable Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Included in cost of revenue	$ 1,295	$ 1,295	$ 2,590	$ 2,590
Included in operating expenses	800	780	1,604	1,554
Total amortization expense	$ 2,095	$ 2,075	$ 4,194	$ 4,144