Stockholders' Equity And Stock-Based Compensation (Schedule of Stock-Based Compensation By Classification) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 26, 2021	Mar. 27, 2020	Mar. 26, 2021	Mar. 27, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 24,413	$ 20,951	$ 50,726	$ 43,565
Benefit from income taxes	(3,859)	(3,521)	(8,071)	(7,115)
Total stock-based compensation, net of tax	20,554	17,430	42,655	36,450
Cost of products [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	489	507	1,123	1,050
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	7,190	6,179	15,123	13,166
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	9,110	7,702	18,906	15,876
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 7,624	$ 6,563	$ 15,574	$ 13,473