SEGMENT INFORMATION - Operating Results Information for Each Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended
Dec. 28, 2018	Dec. 29, 2017
Segment Reporting Information [Line Items]
Revenues	$ 741.0	$ 678.5
Earnings before taxes	111.7	121.6
Interest income, net	2.7	1.1
Other income (expense), net	23.0	(0.2)
Earnings before taxes	137.4	122.5
Oncology Systems
Segment Reporting Information [Line Items]
Revenues	702.5	649.4
Proton Solutions
Segment Reporting Information [Line Items]
Revenues	38.5	29.1
Unallocated corporate
Segment Reporting Information [Line Items]
Earnings before taxes	(3.6)	(1.4)
Operating Segments
Segment Reporting Information [Line Items]
Earnings before taxes	115.3	123.0
Operating Segments \| Oncology Systems
Segment Reporting Information [Line Items]
Revenues	702.5	649.4
Earnings before taxes	124.1	138.2
Operating Segments \| Proton Solutions
Segment Reporting Information [Line Items]
Revenues	38.5	29.1
Earnings before taxes	$ (8.8)	$ (15.2)

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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