Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Apr. 04, 2020	Apr. 04, 2020	Oct. 03, 2020	Sep. 28, 2019	Sep. 29, 2018
Finite-Lived Intangible Assets [Line Items]
Impairment of goodwill			$ 327,203
Asset impairment charges	$ 2,500
Goodwill and intangible asset impairment			451,025	$ 0	$ 766
Amortization of intangible assets			30,100	61,500	$ 60,000
Rofin-Sinar
Finite-Lived Intangible Assets [Line Items]
Goodwill and intangible asset impairment			4,700
Existing technology
Finite-Lived Intangible Assets [Line Items]
Goodwill and intangible asset impairment			$ 27,700
Remaining amortization period			1 year 6 months
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Goodwill and intangible asset impairment			$ 6,200
Remaining amortization period			6 years 1 month 6 days
Production know-how
Finite-Lived Intangible Assets [Line Items]
Remaining amortization period			3 years
Foreign Exchange
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets			$ 2,900	$ 7,800
Industrial Lasers & Systems
Finite-Lived Intangible Assets [Line Items]
Impairment of goodwill			327,203
Industrial Lasers & Systems | Finite-Lived Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Asset impairment charges			33,900
Industrial Lasers & Systems | Property and equipment
Finite-Lived Intangible Assets [Line Items]
Asset impairment charges			85,600
Industrial Lasers & Systems | Right-Of-Use Assets
Finite-Lived Intangible Assets [Line Items]
Asset impairment charges		$ 1,800	$ 1,800