Cover Page - USD ($)	12 Months Ended
	Sep. 28, 2019	Nov. 21, 2019	Mar. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 28, 2019
Document Transition Report	false
Entity File Number	1-36214
Entity Registrant Name	HOLOGIC, INC
Entity Central Index Key	0000859737
Current Fiscal Year End Date	--09-28
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-2902449
Entity Address, Address Line One	250 Campus Drive
Entity Address, City or Town	Marlborough
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01752
City Area Code	508
Local Phone Number	263-2900
Title of 12(b) Security	Common Stock, $.01 par value
Trading Symbol	HOLX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 12,895,201,013
Entity Common Stock, Shares Outstanding		268,145,411
Documents Incorporated by Reference	Portions of the registrant’s Proxy Statement for the registrant’s annual meeting of stockholders to be filed within 120 days of the end of its fiscal year ended September 28, 2019 are incorporated into Part III (Items 10, 11, 12, 13 and 14) of this Annual Report on Form 10-K where indicated.