SEGMENT INFORMATION - Operating Results Information for Each Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended
Jan. 03, 2020	Dec. 28, 2018
Segment Reporting Information [Line Items]
Revenues	$ 828.9	$ 741.0
Earnings from continuing operations before taxes	110.0	111.7
Interest income (expense), net	(1.7)	2.7
Other income, net	4.4	23.0
Earnings before taxes	112.7	137.4
Unallocated corporate
Segment Reporting Information [Line Items]
Earnings from continuing operations before taxes	(14.9)	(3.6)
Operating Segments
Segment Reporting Information [Line Items]
Revenues	810.0	741.0
Earnings from continuing operations before taxes	122.1	115.3
Operating Segments \| Oncology Systems
Segment Reporting Information [Line Items]
Revenues	782.4	702.5
Earnings from continuing operations before taxes	136.4	124.1
Operating Segments \| Proton Solutions
Segment Reporting Information [Line Items]
Revenues	27.6	38.5
Earnings from continuing operations before taxes	(14.3)	(8.8)
Operating Segments \| Other
Segment Reporting Information [Line Items]
Revenues	18.9	0.0
Earnings from continuing operations before taxes	$ 2.8	$ 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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