Summary of Significant Accounting Policies - Rollforward of Goodwill Activity by Reportable Segments (Detail) $ in Thousands	12 Months Ended
Sep. 30, 2017 USD ($)
Goodwill [Roll Forward]
Balance at September 24, 2016	$ 2,803,100
Acquisitions	692,400
Sale of blood screening business	(325,000)
Foreign currency and other adjustments	700
Balance at September 30, 2017	3,171,200
Diagnostics
Goodwill [Roll Forward]
Balance at September 24, 2016	1,148,200
Acquisitions	0
Sale of blood screening business	(325,000)
Foreign currency and other adjustments	(200)
Balance at September 30, 2017	823,000
Breast Health
Goodwill [Roll Forward]
Balance at September 24, 2016	631,800
Acquisitions	8,900
Sale of blood screening business	0
Foreign currency and other adjustments	800
Balance at September 30, 2017	641,500
Medical Aesthetics
Goodwill [Roll Forward]
Balance at September 24, 2016	0
Acquisitions	683,500
Sale of blood screening business	0
Foreign currency and other adjustments	0
Balance at September 30, 2017	683,500
GYN Surgical
Goodwill [Roll Forward]
Balance at September 24, 2016	1,015,000
Acquisitions	0
Sale of blood screening business	0
Foreign currency and other adjustments	100
Balance at September 30, 2017	1,015,100
Skeletal Health
Goodwill [Roll Forward]
Balance at September 24, 2016	8,100
Acquisitions	0
Sale of blood screening business	0
Foreign currency and other adjustments	0
Balance at September 30, 2017	$ 8,100

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=64834752&loc=SL49117168-202975

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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.

+ References

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

+ References

+ Details

Name:	us-gaap_GoodwillForeignCurrencyTranslationGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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.

+ Details

Name:	us-gaap_GoodwillRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

Name:	us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=holx_DiagnosticsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=holx_BreastHealthMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=holx_MedicalAestheticsDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=holx_GynSurgicalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=holx_SkeletalHealthMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: