Stockholders' Equity (Schedule of Reclassifications out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Net revenue	$ 230,852	$ 255,276	$ 479,934	$ 500,477
Cost of revenue	165,407	174,996	332,481	343,878
Research and development	18,814	21,946	37,646	43,137
Sales and marketing	34,541	38,552	70,396	76,426
General and administrative	10,463	18,458	23,580	34,219
Income before income taxes	1,595	1,804	16,645	2,736
Tax impact from continuing operations	(756)	(1,271)	(2,963)	(1,185)
Net income from continuing operations	839	533	13,682	1,551
Net loss from discontinued operations, net of tax	0	(5,763)	0	(1,191)
Net income (loss)	839	(5,230)	13,682	360
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	672	1,187	1,086	(515)
Cost of revenue	(6)	(7)	(8)	(1)
Research and development	(20)	(13)	(46)	86
Sales and marketing	(98)	(157)	(167)	73
General and administrative	(12)	(50)	(23)	(9)
Income before income taxes	536	960	842	(366)
Tax impact from continuing operations	(113)	(202)	(177)	77
Net income from continuing operations	423	758	665	(289)
Net loss from discontinued operations, net of tax	0	471	0	(213)
Net income (loss)	$ 423	$ 1,229	$ 665	$ (502)