Goodwill and Intangible Assets - Activity of Goodwill by Reportable Operating Segment (Detail) - USD ($) $ in Millions	12 Months Ended
Sep. 29, 2017	Sep. 30, 2016
Goodwill [Roll Forward]
Balance, beginning	$ 220.0	$ 208.8
Business combinations		11.4
Foreign currency translation adjustments	2.6	(0.2)
Balance, ending	222.6	220.0
Varian Particle Therapy
Goodwill [Roll Forward]
Balance, beginning	49.8	50.0
Business combinations		0.0
Foreign currency translation adjustments	2.6	(0.2)
Balance, ending	52.4	49.8
Oncology Systems
Goodwill [Roll Forward]
Balance, beginning	170.2	158.8
Business combinations		11.4
Foreign currency translation adjustments	0.0	0.0
Balance, ending	$ 170.2	$ 170.2

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

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- Definition

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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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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- Definition

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

+ References

No definition available.

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