SEGMENT INFORMATION - Operating Results Information for Each Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018
Segment Reporting Information [Line Items]
Revenues	$ 825.8	$ 709.1	$ 2,346.2	$ 2,117.5
Earnings before taxes	53.9	90.0	275.4	304.3
Interest income, net	1.9	0.5	7.6	2.9
Other income, net	4.2	1.5	27.4	2.9
Earnings before taxes	60.0	92.0	310.4	310.1
Oncology Systems
Segment Reporting Information [Line Items]
Revenues	792.9	667.2	2,242.2	2,014.6
Proton Solutions
Segment Reporting Information [Line Items]
Revenues	30.9	41.9	102.0	102.9
Other
Segment Reporting Information [Line Items]
Revenues	2.0		2.0
Unallocated corporate
Segment Reporting Information [Line Items]
Earnings before taxes	(31.0)	(25.5)	(36.5)	(59.8)
Operating Segments
Segment Reporting Information [Line Items]
Revenues	823.8	709.1	2,344.2	2,117.5
Earnings before taxes	86.6	115.5	313.6	364.1
Operating Segments \| Oncology Systems
Segment Reporting Information [Line Items]
Revenues	792.9	667.2	2,242.2	2,014.6
Earnings before taxes	148.7	125.6	404.5	406.9
Operating Segments \| Proton Solutions
Segment Reporting Information [Line Items]
Revenues	30.9	41.9	102.0	102.9
Earnings before taxes	(62.1)	(10.1)	(90.9)	(42.8)
Operating Segments \| Other
Segment Reporting Information [Line Items]
Revenues	2.0	0.0	2.0	0.0
Earnings before taxes	$ (1.7)	$ 0.0	$ (1.7)	$ 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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