Derivative Financial Instruments (Schedule of Effects and Locations of Gains or Losses Recognized in Income) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Net revenue	$ 230,852	$ 255,276	$ 479,934	$ 500,477
Cost of revenue	165,407	174,996	332,481	343,878
Research and development	18,814	21,946	37,646	43,137
Sales and marketing	34,541	38,552	70,396	76,426
General and administrative	10,463	18,458	23,580	34,219
Net revenue \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	672	1,187	1,086	(515)
Cost of revenue \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	(6)	(7)	(8)	(1)
Research and development \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	(20)	(13)	(46)	86
Sales and marketing \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	(98)	(157)	(167)	73
General and administrative \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	$ (12)	$ (50)	$ (23)	$ (9)

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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