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				6 Months Ended
	Jun. 28, 2015		Jun. 29, 2014		Jun. 28, 2015		Jun. 29, 2014
Segment Reporting Information [Line Items]
Total net revenues	$ 288,782		$ 337,604		$ 597,939		$ 686,995
Total segment contribution income	32,706		47,090		74,026		94,832
Corporate and unallocated costs	(12,230)		(13,128)		(25,196)		(26,884)
Amortization of intangible assets	(4,243)	[1]	(4,391)	[1]	(8,639)	[1]	(8,781)
Stock-based compensation expense	(4,058)		(4,934)		(8,406)		(10,064)
Restructuring and other charges	(974)		12		(5,368)		(830)
Acquisition-related expense	0		0		0		(8)
Losses on inventory commitments due to restructuring	0		0		(407)		0
Litigation reserves, net	0		(68)		2,690		(185)
Interest income	67		49		119		106
Other income (expense), net	(343)		(227)		132		(335)
Income before income taxes	10,925		24,403		28,951		47,851
Retail [Member]
Segment Reporting Information [Line Items]
Total net revenues	131,809		110,663		252,766		228,895
Total segment contribution income	$ 16,247		$ 14,726		$ 32,566		$ 29,409
Segment contribution margin (in percentage)	12.30%		13.30%		12.90%		12.80%
Commercial [Member]
Segment Reporting Information [Line Items]
Total net revenues	$ 63,017		$ 75,447		$ 135,748		$ 154,310
Total segment contribution income	$ 12,564		$ 17,129		$ 28,807		$ 36,669
Segment contribution margin (in percentage)	19.90%		22.70%		21.20%		23.80%
Service Provider [Member]
Segment Reporting Information [Line Items]
Total net revenues	$ 93,956		$ 151,494		$ 209,425		$ 303,790
Total segment contribution income	$ 3,895		$ 15,235		$ 12,653		$ 28,754
Segment contribution margin (in percentage)	4.10%		10.10%		6.00%		9.50%

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