Document and Entity Information - shares	3 Months Ended
Mar. 31, 2019	May 14, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2019
Entity Registrant Name	resTORbio, Inc.
Entity Central Index Key	0001720580
Trading Symbol	TORC
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		35,743,278

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

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This is focus fiscal period of the document report. For a first quarter 2006 quarterly report, which may also provide financial information from prior periods, the first fiscal quarter should be given as the fiscal period focus. Values: FY, Q1, Q2, Q3, Q4, H1, H2, M9, T1, T2, T3, M8, CY.

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This is focus fiscal year of the document report in CCYY 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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The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

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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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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
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-Name Regulation 12B
-Number 240
-Section 12
-Subsection b-2

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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Indicate if registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Securities Act
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-Section B
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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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Indicates that the company is a smaller reporting company with both a public float and revenues of less than $75 million.

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Trading symbol of an instrument as listed on an exchange.

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Document and Entity Information [Abstract]

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