SEGMENT INFORMATION - Operating Results Information for Each Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Apr. 03, 2020	Mar. 29, 2019	Apr. 03, 2020	Mar. 29, 2019
Segment Reporting Information [Line Items]
Revenues	$ 794.5	$ 779.4	$ 1,623.4	$ 1,520.4
Earnings before taxes	54.9	109.8	164.9	221.5
Interest income (expense), net	(1.2)	3.0	(2.9)	5.7
Other income (expense), net	(0.9)	0.2	3.5	23.2
Earnings before taxes	52.8	113.0	165.5	250.4
Unallocated corporate
Segment Reporting Information [Line Items]
Earnings before taxes	(39.4)	(1.9)	(54.3)	(5.5)
Operating Segments
Segment Reporting Information [Line Items]
Revenues	782.8	779.4	1,592.8	1,520.4
Earnings before taxes	96.6	111.7	218.7	227.0
Operating Segments \| Oncology Systems
Segment Reporting Information [Line Items]
Revenues	760.5	746.8	1,542.9	1,449.3
Earnings before taxes	110.9	131.7	247.3	255.8
Operating Segments \| Proton Solutions
Segment Reporting Information [Line Items]
Revenues	22.3	32.6	49.9	71.1
Earnings before taxes	(14.3)	(20.0)	(28.6)	(28.8)
Operating Segments \| Other
Segment Reporting Information [Line Items]
Revenues	11.7	0.0	30.6	0.0
Earnings before taxes	$ (2.3)	$ 0.0	$ 0.5	$ 0.0

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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