Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 01, 2017	Oct. 02, 2016	Sep. 27, 2015
Income Taxes [Line Items]
Income Tax Expense (Benefit)	$ (40.2)	$ 7.2	$ 12.3
Income (loss) before income taxes	136.1	(25.4)	96.9
Increase in valuation allowance	77.2	205.9
Excess tax benefit from employee stock compensation	144.3
Tax credits that carryforward indefinitely	1.9
Alternative minimum tax	11.2
Deferred Tax Assets, Capital Loss Carryforwards	0.6
Undistributed earnings of foreign operations	904.3	793.8
Unrecognized tax benefit, interest and penalties	4.2	3.7	$ 0.7
Unrecognized tax benefit, cumulative interest and penalties	38.0	$ 42.2
Unrecognized tax benefit that would impact effective tax rate	107.4
within the next twelve months
Income Taxes [Line Items]
Anticipated decrease in unrecognized tax benefits	18.0
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Net operating losses carryforward, subject to expiration	526.2
Research and experimentation credits	103.4
Federal foreign tax credits	34.5
State and Local Jurisdiction
Income Taxes [Line Items]
Net operating losses carryforward, subject to expiration	730.3
Research and experimentation credits	98.5
Foreign Country
Income Taxes [Line Items]
Research and experimentation credits	116.9
Tax credit related to incentive deductions	$ 34.2
Minimum | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax years by major tax jurisdiction	2007
Maximum | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax years by major tax jurisdiction	2016