Income Taxes - Reconciliation of Income Tax Computed at the Federal Statutory Rate to Actual Tax Expenses (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 02, 2016	Sep. 27, 2015	Sep. 28, 2014
Income Tax Disclosure [Abstract]
Tax computed at federal statutory rate	$ (8.9)	$ 33.9	$ 8.4
State taxes, net of federal impact	0.5	(2.1)	(1.1)
Foreign income taxed at different rates	(7.0)	(33.1)	(24.7)
Tax credits	(10.7)	(5.1)	(2.8)
Stock award compensation	(4.6)	1.3	1.2
Unrecognized tax benefits	30.6	3.7	1.4
Business Combination, Consideration Transferred, Other	(45.6)	0.0	0.0
U.S. tax on foreign income	2.0	1.3	4.1
Non-deductible permanent items	6.2	0.9	0.9
Pre-acquisition loss carryforwards	0.0	0.0	(11.4)
Effective Income Tax Reconciliation, Prior Year Adjustments On Deferred Taxes	5.0	0.0	2.9
Effective Income Tax Reconciliation, Deduction, Foreign Declared Dividends, Amount	2.7	(0.5)	3.6
Withholding taxes	1.1	(0.3)	0.3
Other differences, net	0.6	(1.0)	0.4
Valuation allowance	35.3	13.3	17.6
Income Tax Expense (Benefit)	$ 7.2	$ 12.3	$ 0.8