Stockholders' Equity And Stock-Based Compensation (Schedule of Stock-Based Compensation By Classification) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 25, 2015	Sep. 26, 2014	Sep. 27, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options	$ 328	$ 538	$ 417
Stock-based compensation expense	67,069	65,680	64,328
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	19,606	19,315	19,316
Cost of products [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	949	812	765
Cost of services [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	457	402	387
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	18,682	18,510	17,117
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	24,283	23,236	21,507
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	22,698	22,720	22,685
Restructuring Charges [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 0	$ 0	$ 1,867