Employee Benefit Plans (Schedule of Total Stock-Based Compensation Expense Resulting from Stock Options, Restricted Stock Awards, and the Employee Stock Purchase Plan) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 6,739	$ 7,246	$ 13,197	$ 14,110
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	755	572	1,423	1,135
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	1,288	1,122	2,480	2,134
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	2,085	2,188	4,126	4,393
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 2,611	$ 3,364	$ 5,168	$ 6,448