Goodwill and Identified Intangible Assets - Amortization Expense for Identifiable Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 25, 2020	Sep. 27, 2019	Sep. 25, 2020	Sep. 27, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Included in cost of revenue	$ 0	$ 1,295	$ 950	$ 3,885
Included in operating expenses	752	785	2,264	2,357
Total amortization expense	$ 752	$ 2,080	$ 3,214	$ 6,242

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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