Stock Plans (Summary of Total Compensation Recognized Related to Outstanding Stock Options) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2017	Jul. 03, 2016	Jul. 02, 2017	Jul. 03, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total pre-tax stock-based compensation expense	$ 6,841	$ 5,829	$ 11,767	$ 9,675
Cost of Revenue [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total pre-tax stock-based compensation expense	281	304	541	494
Research and development expenses [Member ]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total pre-tax stock-based compensation expense	377	231	704	400
Selling, general and administrative and other expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total pre-tax stock-based compensation expense	$ 6,183	$ 5,294	$ 10,522	$ 8,781