Derivative Financial Instruments (Schedule of Location and Amount of Gains or Losses Recognized in Income on Cash Flow Hedges) (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]
Revenue	$ 106,116	$ 131,174	$ 247,594	$ 342,760
Cost of revenue	95,613	101,427	225,496	255,666
Research and development	16,701	16,100	52,456	41,929
Sales and marketing	13,657	12,843	42,389	37,123
General and administrative	11,062	$ 8,357	32,512	$ 19,553
Foreign currency contracts \| Gain (losses) on cash flow hedge
Derivative Instruments, Gain (Loss) [Line Items]
Revenue	100		257
Cost of revenue	0		0
Research and development	0		0
Sales and marketing	0		0
General and administrative	0		0
Foreign currency contracts \| Gain (losses) on cash flow hedge \| Amount Reclassified from AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Revenue	86		333
Cost of revenue	0		(2)
Research and development	(3)		(24)
Sales and marketing	(3)		(38)
General and administrative	$ (2)		$ (11)

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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