Income Taxes - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Sep. 27, 2020	Sep. 29, 2019	Sep. 30, 2018	Oct. 01, 2017
Valuation Allowance [Line Items]
Effective tax rate		23.70%	9.30%	21.50%
Reduction in income tax expense due to excess tax benefits on share-based payments		$ 8,300,000	$ 6,400,000	$ 5,100,000
TCJA deferred income tax benefit			$ 2,600,000	$ 10,100,000
Effective tax rates, excluding impact of non-deductible goodwill impairment and transaction costs, excess tax benefits on share-based payments, TCJA, and valuation allowance release		25.60%	24.60%	30.30%
Undistributed earnings of foreign subsidiaries		$ 66,900,000
Incremental federal tax due to repatriation of foreign earnings		2,000,000.0
Valuation allowance		24,395,000	$ 20,543,000
Unrecognized tax benefits		9,228,000	9,169,000	$ 8,328,000	$ 9,337,000
Accrual of additional interest and penalties		800,000	2,600,000	600,000
Reduction in accrued interest and penalties		0	200,000	300,000
Amount of interest and penalties accrued		4,400,000	$ 3,600,000	$ 1,200,000
Foreign
Valuation Allowance [Line Items]
Decrease in deferred tax valuation allowance	$ 22,300,000
Net operating loss carry forwards which expire at various dates		31,600,000
Net operating loss carryforwards		138,400,000
Net operating loss carry forwards which have no expiration date		106,800,000
Capital loss carryforwards		13,800,000
Research and development credits		4,300,000
State
Valuation Allowance [Line Items]
Net operating loss carry forwards which expire at various dates		$ 43,700,000