Stockholders' Equity And Stock-Based Compensation (Schedule Of Stock-Based Compensation Expense By Plan) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 26, 2020	Jun. 28, 2019	Jun. 26, 2020	Jun. 28, 2019
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock-based compensation expense	$ 21,285	$ 18,863	$ 64,850	$ 59,580
Share-based Compensation			64,850	59,580
Benefit from income taxes	(3,392)	(3,320)	(10,507)	(10,545)
Total stock-based compensation, net of tax	17,893	15,543	54,343	49,035
Stock Option [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock-based compensation expense	4,053	4,260	12,573	13,561
Restricted Stock Units (RSUs) [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock-based compensation expense	15,983	13,566	48,800	42,836
Employee Stock Purchase Plan [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock-based compensation expense	1,249	1,037	3,477	3,183
Cost of Sales [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock-based compensation expense	505	428	1,555	1,328
Research and Development Expense [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock-based compensation expense	6,202	5,830	19,368	17,856
Selling and Marketing Expense [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock-based compensation expense	7,892	6,918	23,768	22,352
General and Administrative Expense [Member]
Stockholders' Equity And Stock-Based Compensation [Line Items]
Stock-based compensation expense	$ 6,686	$ 5,687	$ 20,159	$ 18,044