Segment Information, Operations By Geographic Area And Customer Concentration (Schedule Of Reportable Segment And Reconciliation Of Segment Contribution Income To Income Before Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jul. 01, 2012	Apr. 01, 2012	Dec. 31, 2011	Oct. 02, 2011	Jul. 03, 2011	Apr. 03, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Total net revenues	$ 310,436	$ 315,210	$ 320,655	$ 325,620	$ 309,155	$ 301,800	$ 291,240	$ 278,823	$ 1,271,921		$ 1,181,018		$ 902,052
Total segment contribution income									195,428		189,132		148,909
Corporate and unallocated costs									(47,766)		(43,301)		(39,244)
Amortization of intangible assets									(4,763)	[1]	(4,658)	[1]	(5,293)	[1]
Stock-based compensation expense									(14,372)		(13,762)		(12,201)
Restructuring and other charges									(1,190)		(2,094)		88
Acquisition related compensation and expense									(833)		(40)		(686)
Impact to cost of sales from acquisition accounting adjustments to inventory									0		(609)		0
Litigation reserves, net									(390)		201		(211)
Interest income									498		477		426
Other income (expense), net									2,670		(1,136)		(564)
Income before income taxes									129,282		124,210		91,224
Retail [Member]
Segment Reporting Information [Line Items]
Total net revenues									504,797		481,795		435,484
Total segment contribution income									86,808		81,589		71,862
Segment contribution margin (in percentage)									17.20%		16.90%		16.50%
Commercial [Member]
Segment Reporting Information [Line Items]
Total net revenues									307,945		331,439		284,539
Total segment contribution income									67,826		74,746		63,021
Segment contribution margin (in percentage)									22.00%		22.60%		22.10%
Service Provider [Member]
Segment Reporting Information [Line Items]
Total net revenues									459,179		367,784		182,029
Total segment contribution income									$ 40,794		$ 32,797		$ 14,026
Segment contribution margin (in percentage)									8.90%		8.90%		7.70%

[1] Amount excludes amortization expense related to patents within purchased intangible assets in costs of revenues.