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Derivative Instruments and Hedging Activities - Notional and Fair Value (Details) $ in Thousands, € in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2018 USD ($)	Jul. 01, 2017 USD ($)	Dec. 31, 2016 USD ($)	Oct. 01, 2016 USD ($)	Jun. 30, 2018 USD ($)	Jul. 01, 2017 USD ($)	Jun. 30, 2018 EUR (€)	Jun. 30, 2018 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	$ (4,600)	$ 5,600			$ (6,200)	$ 15,000
Not Designated as Hedging Instrument \| Purchase \| Euro Member Countries, Euro
Derivatives, Fair Value [Line Items]
Derivative asset, notional amount								$ 122,343	$ 109,641
Derivative asset, Fair Value								(359)	(1,397)
Not Designated as Hedging Instrument \| Purchase \| China, Yuan Renminbi
Derivatives, Fair Value [Line Items]
Derivative asset, notional amount								6,589	0
Derivative asset, Fair Value								(222)	0
Not Designated as Hedging Instrument \| Purchase \| Singapore, Dollars
Derivatives, Fair Value [Line Items]
Derivative asset, notional amount								33,351	3,668
Derivative asset, Fair Value								(598)	(4)
Not Designated as Hedging Instrument \| Sell \| Euro Member Countries, Euro
Derivatives, Fair Value [Line Items]
Derivative liability, notional amount								(5,492)	0
Derivative liability, Fair Value								72	0
Not Designated as Hedging Instrument \| Sell \| Japan, Yen
Derivatives, Fair Value [Line Items]
Derivative liability, notional amount								(24,052)	(25,126)
Derivative liability, Fair Value								459	591
Not Designated as Hedging Instrument \| Sell \| Korea (South), Won
Derivatives, Fair Value [Line Items]
Derivative liability, notional amount								(36,772)	(28,996)
Derivative liability, Fair Value								1,204	551
Not Designated as Hedging Instrument \| Sell \| China, Yuan Renminbi
Derivatives, Fair Value [Line Items]
Derivative liability, notional amount								(49,399)	(13,744)
Derivative liability, Fair Value								1,415	128
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
Other Foreign Currency Hedge \| Not Designated as Hedging Instrument \| Purchase
Derivatives, Fair Value [Line Items]
Derivative asset, notional amount								2,783	0
Derivative asset, Fair Value								(34)	0
Other Foreign Currency Hedge \| Not Designated as Hedging Instrument \| Sell
Derivatives, Fair Value [Line Items]
Derivative liability, notional amount								(3,508)	(2,971)
Derivative liability, Fair Value								$ 41	$ (74)
Euro term loan \| Euro Member Countries, Euro
Derivatives, Fair Value [Line Items]
Forward contract purchased for the term loan \| €							€ 373.3			€ 670.0	€ 670.0