Consolidated Statements Of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 29, 2019	Mar. 30, 2018	Mar. 29, 2019	Mar. 30, 2018
Income Statement [Abstract]
Net revenue	$ 810.4	$ 913.4	$ 1,782.4	$ 1,965.3
Cost of goods sold	410.2	454.7	897.0	969.8
Gross profit	400.2	458.7	885.4	995.5
Operating expenses:
Research and development	107.5	106.7	216.7	204.7
Selling, general and administrative	47.9	57.5	95.7	108.8
Amortization of acquisition-related intangibles	5.7	4.1	13.1	8.1
Restructuring and other charges	1.5	1.0	1.4	1.0
Total operating expenses	162.6	169.3	326.9	322.6
Operating income	237.6	289.4	558.5	672.9
Other income, net	3.7	2.9	6.6	5.0
Income before income taxes	241.3	292.3	565.1	677.9
Provision for income taxes	27.3	16.3	66.3	331.5
Net income	$ 214.0	$ 276.0	$ 498.8	$ 346.4
Earnings per share:
Basic (in dollars per share)	$ 1.23	$ 1.51	$ 2.85	$ 1.89
Diluted (in dollars per share)	$ 1.23	$ 1.50	$ 2.83	$ 1.87
Weighted average shares:
Basic (in shares)	173.8	182.5	175.2	182.8
Diluted (in shares)	174.6	184.3	176.1	184.9
Cash dividends declared and paid per share (usd per share)	$ 0.38	$ 0.32	$ 0.76	$ 0.64