Income Taxes - Reconciliation of Income Tax Computed at the Federal Statutory Rate to Actual Tax Expenses (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 29, 2013
Income Tax Disclosure [Abstract]
Tax computed at federal statutory rate	$ 33.9	$ 8.4	$ 19.6
State taxes, net of federal impact	(2.1)	(1.1)	(1.6)
Foreign income taxed at different rates	(33.1)	(24.7)	(20.5)
Tax credits	(5.1)	(2.8)	(5.4)
Stock award compensation	1.3	1.2	0.2
Unrecognized tax benefits	3.7	1.4	(0.4)
U.S. tax on foreign income	1.3	4.1	1.4
Income tax return to provision	0.0	(0.2)	(0.9)
Non-deductible permanent items	0.9	0.9	0.2
Pre-acquisition loss carryforwards	0.0	(11.4)	0.0
Effective Income Tax Reconciliation, Prior Year Adjustments On Deferred Taxes	0.0	2.9	0.0
Effective Income Tax Reconciliation, Deduction, Foreign Declared Dividends, Amount	(0.5)	3.6	0.0
Withholding taxes	(0.3)	0.3	0.7
Other differences, net	(1.0)	0.6	0.3
Valuation allowance	13.3	17.6	18.8
Income Tax Expense (Benefit)	$ 12.3	$ 0.8	$ 12.4