Stockholders' Equity And Stock-Based Compensation (Schedule of Stock-Based Compensation By Classification) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 24, 2021	Sep. 25, 2020	Sep. 27, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Recognized tax benefit from the exercise of ISO and ESPP	$ 1,200
Stock-based compensation expense	99,698	$ 86,628	$ 76,580
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	15,790	14,090	12,884
Allocated Share-based Compensation Expense, Net of Tax	83,908	72,538	63,696
Cost of products and services [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	2,033	2,072	1,710
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	29,733	25,634	23,191
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	36,432	31,915	28,137
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 31,500	$ 27,007	$ 23,542