Derivative Financial Instruments (Schedule of Effects and Locations of Gains or Losses Recognized in Income) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Apr. 01, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Net revenue	$ 249,082	$ 245,201
Cost of revenue	167,074	168,882
Research and development	18,832	21,191
Sales and marketing	35,855	37,874
General and administrative	13,117	15,761
Net revenue \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	414	(1,702)
Cost of revenue \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	(2)	6
Research and development \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	(26)	99
Sales and marketing \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	(69)	230
General and administrative \| Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedge	$ (11)	$ 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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