Goodwill and Identified Intangible Assets - Amortization Expense for Identifiable Purchased Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Included in cost of revenue	$ 1,295	$ 1,295	$ 3,885	$ 3,885
Included in operating expenses	792	793	2,396	2,347
Total amortization expense	$ 2,087	$ 2,088	$ 6,281	$ 6,232

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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- Definition

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.

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- Definition

Amount of expense for allocation of cost of intangible asset over its useful life directly used in production of good and rendering of service.

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