Consolidated Statements Of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Dec. 29, 2017	Dec. 30, 2016
Income Statement [Abstract]
Net revenue	$ 1,051.9	$ 914.3
Cost of goods sold	515.1	450.4
Gross profit	536.8	463.9
Operating expenses:
Research and development	98.0	82.0
Selling, general and administrative	51.3	50.9
Amortization of acquisition-related intangibles	4.0	8.5
Restructuring and other charges	0.0	0.6
Total operating expenses	153.3	142.0
Operating income	383.5	321.9
Other income (expense), net	2.1	(0.8)
Income before income taxes	385.6	321.1
Provision for income taxes	315.2	63.3
Net income	$ 70.4	$ 257.8
Earnings per share:
Basic (in dollars per share)	$ 0.38	$ 1.39
Diluted (in dollars per share)	$ 0.38	$ 1.38
Weighted average shares:
Basic (in shares)	183.1	184.8
Diluted (in shares)	185.5	187.3
Cash dividends declared and paid per share (usd per share)	$ 0.32	$ 0.28