Derivative Financial Instruments (Schedule of Company's Derivative Instruments on Other Comprehensive Income and the Consolidated Statement of Operations) (Details) - Foreign currency forward contracts - 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]
Gains (losses) recognized in OCI - Effective Portion	$ 458	$ 625	$ 1,322	$ 1,075
Gains (Losses) Reclassified from OCI into Income - Effective Portion	495	597	1,338	231
Net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	548	750	1,634	235
Cost of revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	(2)	(6)	(10)	(7)
Research and development
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	(2)	0	(47)	86
Sales and marketing
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	(42)	(115)	(209)	(42)
General and administrative
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	$ (7)	$ (32)	$ (30)	$ (41)