GOODWILL AND INTANGIBLE ASSETS - Intangible Assets (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jul. 03, 2020	Jun. 28, 2019	Jul. 03, 2020	Jun. 28, 2019	Sep. 27, 2019
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 137,600,000		$ 137,600,000		$ 137,500,000
Accumulated amortization	(67,000,000.0)		(67,000,000.0)		(54,000,000.0)
Total intangible assets with finite lives, net carrying amount	70,600,000		70,600,000		83,500,000
In-process research and development with indefinite lives	0		0		2,800,000
Total intangible assets	137,600,000		137,600,000		140,300,000
Total intangible assets, net	70,600,000		70,600,000		86,300,000
Amortization of intangible assets	4,200,000	$ 4,100,000	13,100,000	$ 11,400,000
Intangible assets impairment	2,800,000	$ 4,000,000.0	2,800,000	$ 4,800,000
Indefinite-lived intangible assets (excluding goodwill), fair value disclosure	$ 0		$ 0
Measurement Input, Cost of Capital
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets (excluding goodwill), measurement input	25.00%		25.00%
Acquired existing technology
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 74,100,000		$ 74,100,000		74,100,000
Accumulated amortization	(35,200,000)		(35,200,000)		(28,400,000)
Total intangible assets with finite lives, net carrying amount	38,900,000		38,900,000		45,700,000
Patents, licenses and other
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	12,800,000		12,800,000		12,700,000
Accumulated amortization	(9,400,000)		(9,400,000)		(8,400,000)
Total intangible assets with finite lives, net carrying amount	3,400,000		3,400,000		4,300,000
Customer contracts and supplier relationship
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	50,700,000		50,700,000		50,700,000
Accumulated amortization	(22,400,000)		(22,400,000)		(17,200,000)
Total intangible assets with finite lives, net carrying amount	$ 28,300,000		$ 28,300,000		$ 33,500,000