Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 29, 2013
Income Taxes [Line Items]
Income Tax Expense (Benefit)	$ 12.3	$ 0.8	$ 12.4
Income (loss) before income taxes	96.9	23.9	56.1
Increase in valuation allowance	(31.6)	8.9
Excess tax benefit from employee stock compensation	51.6
Estimated increase in equity from excess tax benefit	51.6
Tax credits that carryforward indefinitely	8.9
Undistributed earnings of foreign operations	471.2	430.4
Unrecognized tax benefit, interest and penalties	0.7	0.7	$ 0.1
Unrecognized tax benefit, cumulative interest and penalties	7.4	$ 6.6
Unrecognized tax benefit that would impact effective tax rate	62.5
within the next twelve months
Income Taxes [Line Items]
Anticipated decrease in unrecognized tax benefits	28.3
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Net operating losses carryforward, subject to expiration	366.4
Research and experimentation credits	52.3
Federal foreign tax credits	4.7
State and Local Jurisdiction
Income Taxes [Line Items]
Net operating losses carryforward, subject to expiration	253.1
Research and experimentation credits	91.9
Foreign Country
Income Taxes [Line Items]
Net operating losses carryforward, not subject to expiration	283.7
Research and experimentation credits	81.9
Tax credit related to incentive deductions	$ 16.2
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	2011
Maximum | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax years by major tax jurisdiction	2014
Maximum | Foreign Country
Income Taxes [Line Items]
Open tax years by major tax jurisdiction	2014