GOODWILL AND INTANGIBLE ASSETS - Activity of Goodwill by Reportable Operating Segment (Detail) - USD ($) $ in Millions	3 Months Ended
Jan. 03, 2020	Sep. 27, 2019
Goodwill [Roll Forward]
Balance, beginning	$ 612.2
Business combination	0.3
Measurement period adjustments to business combinations in prior year	(0.1)
Balance, ending	612.4
Oncology Systems
Goodwill [Roll Forward]
Balance, beginning	447.9
Business combination	0.3
Measurement period adjustments to business combinations in prior year	(0.1)
Balance, ending	448.1
Other
Goodwill [Roll Forward]
Balance, beginning	164.3
Business combination	0.0
Measurement period adjustments to business combinations in prior year	0.0
Balance, ending	164.3
Proton Solutions
Goodwill [Roll Forward]
Accumulated impairment charges	$ 50.5	$ 50.5

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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