Goodwill and Identified Intangible Assets - Estimated Future Amortization Expense of Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 29, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
2019 (remaining nine months)	$ 6,241
2020	3,965
2021	498
Total future amortization expense	10,704	$ 12,817
Cost of Revenue [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2019 (remaining nine months)	3,885
2020	951
2021	0
Total future amortization expense	4,836
Operating Expense [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2019 (remaining nine months)	2,356
2020	3,014
2021	498
Total future amortization expense	$ 5,868