Stockholders' Equity And Stock-Based Compensation (Schedule of Stock-Based Compensation By Classification) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 25, 2015	Sep. 26, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 66,985	$ 67,069	$ 65,680
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	19,627	19,606	19,315
Allocated Share-based Compensation Expense, Net of Tax	47,358	47,463	46,365
Recognized tax benefit from the exercise of ISO and ESPP	550	328	538
Cost of products [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	859	949	812
Cost of services [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	547	457	402
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	17,771	18,682	18,510
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	27,579	24,283	23,236
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 20,229	$ 22,698	$ 22,720