Stockholders' Equity And Stock-Based Compensation (Schedule of Stock-Based Compensation By Classification) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Apr. 01, 2016	Mar. 27, 2015	Apr. 01, 2016	Mar. 27, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 16,086	$ 16,667	$ 35,466	$ 34,509
Benefit from income taxes	(4,706)	(4,890)	(10,412)	(10,041)
Total stock-based compensation, net of tax	11,380	11,777	25,054	24,468
Cost of products [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	219	224	499	470
Cost of services [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	114	115	243	237
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,268	4,938	9,375	10,212
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	6,441	5,576	14,151	11,485
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 5,044	$ 5,814	$ 11,198	$ 12,105