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RELATED-PARTY TRANSACTIONS - Investment in Privately-Held Companies Narrative (Details) $ in Millions	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	May 13, 2020 USD ($)	Oct. 31, 2013	Apr. 03, 2020 USD ($) member	Mar. 29, 2019 USD ($)	Apr. 03, 2020 USD ($) member	Mar. 29, 2019 USD ($)	Dec. 31, 2020 USD ($)	Sep. 27, 2019 USD ($)	Nov. 30, 2018
Related Party Transaction [Line Items]
(Loss) income from equity method investments					$ (0.7)	$ 0.3
Dpi X LLC
Related Party Transaction [Line Items]
Equity method investment, ownership percentage			100.00%		100.00%
dpiX Holding \| Varian
Related Party Transaction [Line Items]
Equity method investment, ownership percentage			40.00%		40.00%
Number of consortium members \| member			4		4
(Loss) income from equity method investments			$ (0.8)	$ 0.0	$ 0.1	(0.7)
Equity method investments			47.9		47.9			$ 48.1
Purchases from related party			5.3	$ 1.4	10.9	$ 4.2
Accounts payable, related parties			7.0		7.0			3.6
Percentage of manufacturing capacity		50.00%
Percentage of fixed costs		50.00%
VEC Imaging GmbH & Co. KG
Related Party Transaction [Line Items]
Equity method investment, ownership percentage									50.00%
Equity method investments			2.6		$ 2.6			$ 2.0
Payments to acquire equity method investments			4.0
Fixed Cost Commitments \| dpiX Holding \| Varian
Related Party Transaction [Line Items]
Purchases from related party			$ 9.5
Scenario, Forecast \| VEC Imaging GmbH & Co. KG
Related Party Transaction [Line Items]
Payments to acquire equity method investments	$ 1.1
Scenario, Forecast \| Fixed Cost Commitments \| dpiX Holding \| Varian
Related Party Transaction [Line Items]
Purchases from related party							$ 12.7