Segment Information and Operations By Geographic Area (Schedule Of Reportable Segment And Reconciliation Of Segment Contribution Income To Income Before Income Taxes) (Details) - USD ($) $ in Thousands		3 Months Ended
		Apr. 03, 2016	Mar. 29, 2015
Segment Reporting Information [Line Items]
Total net revenues		$ 310,256	$ 309,157
Total segment contribution income		53,594	41,320
Corporate and unallocated costs		(16,716)	(12,966)
Amortization of intangible assets	[1]	(4,165)	(4,396)
Stock-based compensation expense		(4,411)	(4,348)
Restructuring and other charges		(2,678)	(4,394)
Losses on inventory commitments due to restructuring		0	(407)
Litigation reserves, net		(10)	2,690
Interest income		234	52
Other income (expense), net		(366)	475
Income before income taxes		25,482	18,026
Retail [Member]
Segment Reporting Information [Line Items]
Total net revenues		157,543	120,957
Total segment contribution income		$ 24,299	$ 16,319
Segment contribution margin (in percentage)		15.40%	13.50%
Commercial [Member]
Segment Reporting Information [Line Items]
Total net revenues		$ 68,432	$ 72,731
Total segment contribution income		$ 14,837	$ 16,243
Segment contribution margin (in percentage)		21.70%	22.30%
Service Provider [Member]
Segment Reporting Information [Line Items]
Total net revenues		$ 84,281	$ 115,469
Total segment contribution income		$ 14,458	$ 8,758
Segment contribution margin (in percentage)		17.20%	7.60%

[1] Amount excludes amortization expense related to patents included in cost of revenue.