Stockholder's Equity (Share Based Compensation) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 27, 2019	Dec. 28, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Document Period End Date	Dec. 27, 2019
Share-based compensation expense	$ 33.6	$ 20.8
Cost of sales [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	4.2	3.6
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	14.8	12.5
Selling, general and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 14.6	$ 4.7