Consolidated Statements Of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 30, 2018	Mar. 31, 2017	Mar. 30, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net revenue	$ 913.4	$ 851.7	$ 1,965.3	$ 1,766.0
Cost of goods sold	454.7	426.3	969.8	876.7
Gross profit	458.7	425.4	995.5	889.3
Operating expenses:
Research and development	106.7	89.4	204.7	171.4
Selling, general and administrative	57.5	47.8	108.8	98.7
Amortization of acquisition-related intangibles	4.1	7.0	8.1	15.5
Restructuring and other charges	1.0	0.0	1.0	0.6
Total operating expenses	169.3	144.2	322.6	286.2
Operating income	289.4	281.2	672.9	603.1
Other income (expense), net	2.9	0.2	5.0	(0.6)
Income before income taxes	292.3	281.4	677.9	602.5
Provision for income taxes	16.3	56.5	331.5	119.8
Net income	$ 276.0	$ 224.9	$ 346.4	$ 482.7
Earnings per share:
Basic (in dollars per share)	$ 1.51	$ 1.22	$ 1.89	$ 2.61
Diluted (in dollars per share)	$ 1.50	$ 1.20	$ 1.87	$ 2.58
Weighted average shares:
Basic (in shares)	182.5	184.8	182.8	184.8
Diluted (in shares)	184.3	187.1	184.9	187.2
Cash dividends declared and paid per share (usd per share)	$ 0.32	$ 0.28	$ 0.64	$ 0.56