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Derivative Instruments and Hedging Activities - Notional and Fair Value (Details) $ in Thousands, € in Millions	3 Months Ended
	Dec. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Oct. 01, 2016 USD ($)	Dec. 30, 2017 EUR (€)	Dec. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Nov. 07, 2016 EUR (€)	Aug. 01, 2016 EUR (€)	Aug. 01, 2016 USD ($)
Derivatives, Fair Value [Line Items]
Gain (loss) on derivatives	$ (2,600)	$ 9,500
Foreign currency contracts
Derivatives, Fair Value [Line Items]
Term loan obtain at Rofin acquisition									$ 750,000
Unrealized gain (loss) on derivatives			$ (2,200)
Net gain from forward contracts settlement		9,100
Derivative, gain (loss) on derivative, net		$ 11,300
Purchase \| Not Designated as Hedging Instrument \| Euro Member Countries, Euro
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount					$ 116,372	$ 109,641
Derivative Asset, Fair Value, Gross Asset					(669)	(1,397)
Purchase \| Not Designated as Hedging Instrument \| Korea (South), Won
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount					29,580	0
Derivative Asset, Fair Value, Gross Asset					362	0
Purchase \| Other Foreign Currency Hedge \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount					9,562	3,668
Derivative Asset, Fair Value, Gross Asset					2	(4)
Sell \| Not Designated as Hedging Instrument \| Euro Member Countries, Euro
Derivatives, Fair Value [Line Items]
Derivative Liability, Notional Amount					(33,588)	0
Derivative Liability, Fair Value, Gross Liability					(44)	0
Sell \| Not Designated as Hedging Instrument \| Japan, Yen
Derivatives, Fair Value [Line Items]
Derivative Liability, Notional Amount					(10,818)	(25,126)
Derivative Liability, Fair Value, Gross Liability					224	591
Sell \| Not Designated as Hedging Instrument \| Korea (South), Won
Derivatives, Fair Value [Line Items]
Derivative Liability, Notional Amount					(49,721)	(28,996)
Derivative Liability, Fair Value, Gross Liability					(140)	551
Sell \| Not Designated as Hedging Instrument \| China, Yuan Renminbi
Derivatives, Fair Value [Line Items]
Derivative Liability, Notional Amount					(15,138)	(13,744)
Derivative Liability, Fair Value, Gross Liability					(97)	128
Sell \| Other Foreign Currency Hedge \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Liability, Notional Amount					(2,077)	(2,971)
Derivative Liability, Fair Value, Gross Liability					$ (12)	$ (74)
Euro term loan \| Euro Member Countries, Euro
Derivatives, Fair Value [Line Items]
forward contract purchased for the term loan \| €				€ 436.6			€ 670.0	€ 670.0