Stock-based Compensation (Narrative) (Details)	3 Months Ended		9 Months Ended
	Jun. 30, 2018 USD ($) shares / unit	Jul. 01, 2017 USD ($)	Jun. 30, 2018 USD ($) shares / unit	Jul. 01, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Common Stock Issuable per Restricted Stock Unit | shares / unit	1		1
ESPP maximum contribution percentage	10.00%		10.00%
ESPP maximum contribution amount by employee			$ 25,000
ESPP purchase price as a % of stock price	85.00%		85.00%
Stock-based compensation	$ 16,658,000	$ 16,574,000	$ 52,015,000	$ 56,139,000
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,100,000	$ 900,000	$ 3,200,000	$ 2,200,000