v3.22.1

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2021	Feb. 25, 2022	Jun. 30, 2021
Document and Entity Information [Abstract]
Document Type	10-K/A
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	001-38670
Entity Registrant Name	Entasis Therapeutics Holdings Inc.
Entity Central Index Key	0001724344
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-4592913
Entity Address, Address Line One	35 Gatehouse Drive
Entity Address, City or Town	Waltham
Entity Address State Or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	781
Local Phone Number	810-0120
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	ETTX
Security Exchange Name	NASDAQ
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$ 28.6
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		47,851,779
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Auditor Name	KPMG LLP
Auditor Firm ID	185
Auditor Location	Boston, Massachusetts

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PCAOB issued Audit Firm Identifier

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 10-K
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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-Subsection f

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Area code of city

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Cover page.

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End date of current fiscal year in the format --MM-DD.

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Boolean flag that is true only for a form used as an annual report.

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Fiscal period values are FY, Q1, Q2, and Q3. 1st, 2nd and 3rd quarter 10-Q or 10-QT statements have value Q1, Q2, and Q3 respectively, with 10-K, 10-KT or other fiscal year statements having FY.

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This is focus fiscal year of the document report in YYYY format. For a 2006 annual report, which may also provide financial information from prior periods, fiscal 2006 should be given as the fiscal year focus. Example: 2006.

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For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

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Address Line 1 such as Attn, Building Name, Street Name

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Name of the City or Town

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Name of the state or province.

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A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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Indicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. Where multiple classes or units exist define each class/interest by adding class of stock items such as Common Class A [Member], Common Class B [Member] or Partnership Interest [Member] onto the Instrument [Domain] of the Entity Listings, Instrument.

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Indicate 'Yes' or 'No' whether registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that registrants were required to file such reports), and (2) have been subject to such filing requirements for the past 90 days. This information should be based on the registrant's current or most recent filing containing the related disclosure.

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No definition available.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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-Section 12
-Subsection b-2

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Securities Act
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Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

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No definition available.

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Indicate whether the registrant is one of the following: Large Accelerated Filer, Accelerated Filer, Non-accelerated Filer. Definitions of these categories are stated in Rule 12b-2 of the Exchange Act. This information should be based on the registrant's current or most recent filing containing the related disclosure.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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Two-character EDGAR code representing the state or country of incorporation.

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Boolean flag that is true when the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The aggregate market value of the voting and non-voting common equity held by non-affiliates computed by reference to the price at which the common equity was last sold, or the average bid and asked price of such common equity, as of the last business day of the registrant's most recently completed second fiscal quarter.

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No definition available.

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The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
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Boolean flag that is true when the registrant is a shell company as defined in Rule 12b-2 of the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Indicates that the company is a Smaller Reporting Company (SRC).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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-Section 12
-Subsection b-2

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The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Indicate 'Yes' or 'No' if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

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No definition available.

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Indicate 'Yes' or 'No' if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Is used on Form Type: 10-K, 10-Q, 8-K, 20-F, 6-K, 10-K/A, 10-Q/A, 20-F/A, 6-K/A, N-CSR, N-Q, N-1A.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Local phone number for entity.

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Title of a 12(b) registered security.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Section 12
-Subsection b

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Name of the Exchange on which a security is registered.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Trading symbol of an instrument as listed on an exchange.

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Entasis Therapeutics Holdings Inc. 10-K/A