Stockholders' Equity And Stock-Based Compensation (Schedule of Stock-Based Compensation By Classification) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 27, 2020	Mar. 29, 2019	Mar. 27, 2020	Mar. 29, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 20,951	$ 19,235	$ 43,565	$ 40,717
Benefit from income taxes	(3,521)	(3,465)	(7,115)	(7,225)
Total stock-based compensation, net of tax	17,430	15,770	36,450	33,492
Cost of products [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	507	412	1,050	900
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	6,179	5,785	13,166	12,026
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	7,702	7,217	15,876	15,434
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 6,563	$ 5,821	$ 13,473	$ 12,357

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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