Goodwill and Identified Intangible Assets - Amortization Expense for Identifiable Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Included in cost of revenue	$ 1,295	$ 1,380	$ 3,885	$ 3,105
Included in operating expenses	793	3,009	2,347	9,606
Total amortization expense	$ 2,088	$ 4,389	$ 6,232	$ 12,711