Derivatives - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017	Sep. 30, 2017
Estimated unrealized gains (losses), net of tax, expected to be reclassified in next 12 months			$ (100,000)
Gains (losses) recognized in income for derivatives related to ineffective portions and amounts excluded from effectiveness testing	$ 0	$ 0	0	$ 0
Derivatives designated as hedging instruments | Derivatives in Cash Flow Hedging Relationships | Forward currency forward contracts
Notional amount of forward exchange contracts	73,800,000		73,800,000		$ 67,000,000
Fair value of derivative asset					2,000,000
Fair value of derivative liability	100,000		100,000
Derivatives not designated as hedging instruments | Forward currency forward contracts
Notional amount of forward exchange contracts	24,900,000		24,900,000		10,600,000
Fair value of derivative asset	$ 300,000		$ 300,000
Fair value of derivative liability					$ 100,000