Summary of Significant Accounting Policies - Rollforward of Goodwill Activity by Reportable Segments (Detail) $ in Millions	12 Months Ended
Sep. 26, 2020 USD ($)
Goodwill [Roll Forward]
Balance at September 28, 2019	$ 2,563.7
Foreign currency and other adjustments	5.3
Balance at September 26, 2020	2,657.9
Diagnostics
Goodwill [Roll Forward]
Balance at September 28, 2019	819.2
Foreign currency and other adjustments	2.4
Balance at September 26, 2020	821.6
Breast Health
Goodwill [Roll Forward]
Balance at September 28, 2019	722.2
Foreign currency and other adjustments	2.1
Balance at September 26, 2020	764.8
Gyn Surgical [Member]
Goodwill [Roll Forward]
Balance at September 28, 2019	1,014.2
Foreign currency and other adjustments	0.8
Balance at September 26, 2020	1,063.4
Skeletal Health
Goodwill [Roll Forward]
Balance at September 28, 2019	8.1
Foreign currency and other adjustments	0.0
Balance at September 26, 2020	8.1
SuperSonic Imagine
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	34.3
SuperSonic Imagine \| Diagnostics
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	0.0
SuperSonic Imagine \| Breast Health
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	34.3
SuperSonic Imagine \| Gyn Surgical [Member]
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	0.0
SuperSonic Imagine \| Skeletal Health
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	0.0
Health Beacons
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	6.2
Balance at September 26, 2020	6.2
Health Beacons \| Diagnostics
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	0.0
Health Beacons \| Breast Health
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	6.2
Health Beacons \| Gyn Surgical [Member]
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	0.0
Health Beacons \| Skeletal Health
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	0.0
Acessa Health [Member]
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	48.4
Acessa Health [Member] \| Diagnostics
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	0.0
Acessa Health [Member] \| Breast Health
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	0.0
Acessa Health [Member] \| Gyn Surgical [Member]
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	48.4
Acessa Health [Member] \| Skeletal Health
Goodwill [Roll Forward]
SuperSonic Imagine acquisition	$ 0.0

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://fasb.org/us-gaap/role/ref/legacyRef
-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

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

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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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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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.

+ References

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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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