Goodwill and Identified Intangible Assets - Estimated Future Amortization Expense of Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 28, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
2019 (remaining six months)	$ 4,166
2020	3,974
2021	500
Total future amortization expense	8,640	$ 12,817
Cost of Revenue [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2019 (remaining six months)	2,590
2020	951
2021	0
Total future amortization expense	3,541
Operating Expense [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2019 (remaining six months)	1,576
2020	3,023
2021	500
Total future amortization expense	$ 5,099