Income Taxes - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Sep. 28, 2019	Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Tax Expense (Benefit) of Undistributed Earnings of Foreign Subsidiaries		$ (10.5)
Additions (reductions) to valuation allowance	$ (3.6)	1.9	$ (32.9)	$ 14.9
Increase (Decrease) to valuation allowance		0.8
Uncertain tax benefits	2.3	2.3
Unrecognized tax benefits that would reduce company's effective tax rate if recognized	1.5	1.5	4.6
Total accrued penalties and net accrued interest with respect to income taxes	0.2	0.2	0.2	0.2
Expense recognized for accrued penalties and net accrued interest (less than)		0.1	0.1	0.1
Other liabilities (noncurrent)
Uncertain tax benefits	1.5	1.5
Deferred income taxes (noncurrent asset)
Uncertain tax benefits	0.8	0.8
Foreign Tax Authority
Net operating loss carryforwards	79.6	79.6
State Jurisdiction
Net operating loss carryforwards	$ 189.2	189.2
Tax Cuts and Jobs Act of 2017
Additions (reductions) to valuation allowance			(9.7)
SEC Schedule, 12-09, Valuation Allowance, Operating Loss Carryforward
Additions (reductions) to valuation allowance			(21.0)
Global intangible low-taxed income
Additions (reductions) to valuation allowance			(3.6)
APAC
Tax reductions related to tax holiday		$ 23.9	$ 39.1	$ 37.5
Tax reductions related to tax holiday, basic (in dollars per share)		$ 0.79	$ 1.19	$ 1.11
Tax reductions related to tax holiday, diluted (in dollars per share)		$ 0.77	$ 1.15	$ 1.08
EMEA
Additions (reductions) to valuation allowance			$ 1.4
Increase (Decrease) to valuation allowance		$ 0.9
AMER
Increase (Decrease) to valuation allowance		$ (1.7)