Stockholders' Equity (Schedule of Reclassifications out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Net revenue	$ 265,858	$ 269,411	$ 745,792	$ 769,888
Cost of revenue	188,666	174,966	521,147	518,844
Research and development	19,537	20,136	57,183	63,273
Sales and marketing	33,491	37,892	103,887	114,318
General and administrative	11,887	16,184	35,467	50,403
Income before income taxes	12,301	21,793	28,946	24,529
Tax impact from continuing operations	228	(5,483)	(2,735)	(6,668)
Net income from continuing operations	12,529	16,310	26,211	17,861
Net loss from discontinued operations, net of tax	0	(7,160)	0	(8,351)
Net income	12,529	9,150	26,211	9,510
Amount Reclassified from AOCI | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Net revenue	548	750	1,634	235
Cost of revenue	(2)	(6)	(10)	(7)
Research and development	(2)	0	(47)	86
Sales and marketing	(42)	(115)	(209)	(42)
General and administrative	(7)	(32)	(30)	(41)
Income before income taxes	495	597	1,338	231
Tax impact from continuing operations	(104)	(125)	(281)	(49)
Net income from continuing operations	391	472	1,057	182
Net loss from discontinued operations, net of tax	0	197	0	(15)
Net income	$ 391	$ 669	$ 1,057	$ 167