Derivative Financial Instruments (Schedule of Effects and Locations of Gains or Losses Recognized in Income) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Net revenue	$ 265,858	$ 269,411	$ 745,792	$ 769,888
Cost of revenue	188,666	174,966	521,147	518,844
Research and development	19,537	20,136	57,183	63,273
Sales and marketing	33,491	37,892	103,887	114,318
General and administrative	11,887	16,184	35,467	50,403
Net revenue \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	548	750	1,634	235
Cost of revenue \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	(2)	(6)	(10)	(7)
Research and development \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	(2)	0	(47)	86
Sales and marketing \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	(42)	(115)	(209)	(42)
General and administrative \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	$ (7)	$ (32)	$ (30)	$ (41)

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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The aggregate total amount of expenses directly related to the marketing or selling of products or services.

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