Consolidated Statements Of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Dec. 28, 2018	Dec. 29, 2017
Income Statement [Abstract]
Net revenue	$ 972.0	$ 1,051.9
Cost of goods sold	486.9	515.1
Gross profit	485.1	536.8
Operating expenses:
Research and development	109.2	98.0
Selling, general and administrative	47.8	51.3
Amortization of intangibles	7.4	4.0
Restructuring and other charges (benefits)	(0.2)	0.0
Total operating expenses	164.2	153.3
Operating income	320.9	383.5
Other income, net	2.9	2.1
Income before income taxes	323.8	385.6
Provision for income taxes	38.9	315.2
Net income	$ 284.9	$ 70.4
Earnings per share:
Basic (in dollars per share)	$ 1.61	$ 0.38
Diluted (in dollars per share)	$ 1.60	$ 0.38
Weighted average shares:
Basic (in shares)	176.6	183.1
Diluted (in shares)	177.7	185.5
Cash dividends declared and paid per share (usd per share)	$ 0.38	$ 0.32