Goodwill and Identified Intangible Assets - Estimated Future Amortization Expense of Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 25, 2020	Dec. 31, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
2020 (remaining three months)	$ 754
2021	502
Total future amortization expense	1,256	$ 4,461
Cost of Revenue [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2020 (remaining three months)	0
2021	0
Total future amortization expense	0
Operating Expense [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2020 (remaining three months)	754
2021	502
Total future amortization expense	$ 1,256