Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 02, 2016	Sep. 27, 2015	Sep. 28, 2014
Income Taxes [Line Items]
Income Tax Expense (Benefit)	$ 7.2	$ 12.3	$ 0.8
Income (loss) before income taxes	(25.4)	96.9	23.9
Increase in valuation allowance	(205.9)	31.6
Excess tax benefit from employee stock compensation	213.5
Tax credits that carryforward indefinitely	9.0
Deferred Tax Assets, Capital Loss Carryforwards	0.6
Undistributed earnings of foreign operations	793.8	471.2
Unrecognized tax benefit, interest and penalties	3.7	0.7	$ 0.7
Unrecognized tax benefit, cumulative interest and penalties	42.0	$ 7.4
Unrecognized tax benefit that would impact effective tax rate	114.9
within the next twelve months
Income Taxes [Line Items]
Anticipated decrease in unrecognized tax benefits	17.2
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Net operating losses carryforward, subject to expiration	671.7
Research and experimentation credits	125.5
Federal foreign tax credits	38.4
State and Local Jurisdiction
Income Taxes [Line Items]
Net operating losses carryforward, subject to expiration	713.6
Research and experimentation credits	111.2
Foreign Country
Income Taxes [Line Items]
Research and experimentation credits	139.6
Tax credit related to incentive deductions	$ 26.2
Minimum | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax years by major tax jurisdiction	2007
Minimum | Foreign Country
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	2015
Maximum | Foreign Country
Income Taxes [Line Items]
Open tax years by major tax jurisdiction	2015