SEGMENT INFORMATION - Operating Results Information for Each Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended
Jan. 01, 2021	Jan. 03, 2020
Segment Reporting Information [Line Items]
Revenues	$ 778.8	$ 828.9
Earnings before taxes	117.2	110.0
Interest income (expense), net	1.5	(1.7)
Other income, net	5.7	4.4
Earnings before taxes	124.4	112.7
Operating Segments
Segment Reporting Information [Line Items]
Revenues	770.1	810.0
Earnings before taxes	131.5	122.1
Operating Segments \| Oncology Systems
Segment Reporting Information [Line Items]
Revenues	744.5	782.4
Earnings before taxes	142.0	136.4
Operating Segments \| Proton Solutions
Segment Reporting Information [Line Items]
Revenues	25.6	27.6
Earnings before taxes	(10.5)	(14.3)
Other
Segment Reporting Information [Line Items]
Revenues	8.7	18.9
Earnings before taxes	(5.3)	2.8
Unallocated corporate
Segment Reporting Information [Line Items]
Earnings before taxes	$ (9.0)	$ (14.9)

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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