Organization	9 Months Ended
Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	1. Organization resTORbio, Inc. (collectively referred to with its wholly-owned, controlled subsidiary, resTORbio Securities Corp. as “resTORbio” or the “Company”) was incorporated in the State of Delaware on July 5, 2016. The Company is a clinical-stage biopharmaceutical company focused on the development and commercialization of novel therapeutics for the treatment of aging-related diseases and conditions. The Company’s principal operations are located in Boston, Massachusetts. Since inception, the Company has been primarily involved in research and development activities. The Company devotes substantially all of its efforts to product research and development, initial market development and raising capital. The Company has not generated any product revenue related to its primary business purpose to date and is subject to a number of risks similar to those of other early stage companies, including dependence on key individuals, competition from other companies, the need for development of commercially viable products and the need to obtain adequate additional financing to fund the development of its product candidates. The Company is also subject to a number of risks similar to other companies in the life sciences industry, including regulatory approval of products, uncertainty of market acceptance of products, competition from substitute products and larger companies, the need to obtain additional financing, compliance with government regulations, protection of proprietary technology, dependence on third parties, product liability and dependence on key individuals. Reverse Stock Split On January 12, 2018, the Company effected a one-for-1.2804 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company’s redeemable convertible preferred stock (see Note 8). Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse stock split and adjustment of the preferred stock conversion ratios. Initial Public Offering On January 30, 2018, the Company completed its initial public offering (“IPO”), whereby the Company sold 6,516,667 shares of its common stock (inclusive of 850,000 shares of common stock sold by the Company pursuant to the full exercise of an overallotment option granted to the underwriters in connection with the offering) at a price of $15.00 per share. The shares began trading on The Nasdaq Global Select Market on January 26, 2018. The aggregate net proceeds received by the Company from the offering were approximately $89.4 million, after deducting underwriting discounts and commissions and other offering expenses payable by the Company of $8.4 million. Upon the closing of the IPO, all outstanding shares of redeemable convertible preferred stock converted into 15,870,559 shares of common stock and all unvested shares of restricted stock automatically vested. Additionally, the Company is now authorized to issue 150,000,000 shares of common stock and 10,000,000 shares of preferred stock. Liquidity In the course of its development activities, the Company has sustained operating losses and expects such losses to continue over the next several years. The Company’s ultimate success depends on the outcome of its research and development activities. The Company has incurred net losses from operations since inception and has an accumulated deficit of $65.6 million as of September 30, 2018. On January 30, 2018, the Company completed its IPO whereby the Company sold 6,516,667 shares of its common stock for aggregate net proceeds of approximately $89.4 million. As of September 30, 2018, the Company had $115.4 million of cash, cash equivalents, and marketable securities, which the Company believes will be sufficient to fund the Company’s current operating plan through at least the next twelve months.

1. Organization

resTORbio, Inc. (collectively referred to with its wholly-owned, controlled subsidiary, resTORbio Securities Corp. as “resTORbio” or the “Company”) was incorporated in the State of Delaware on July 5, 2016. The Company is a clinical-stage biopharmaceutical company focused on the development and commercialization of novel therapeutics for the treatment of aging-related diseases and conditions. The Company’s principal operations are located in Boston, Massachusetts.

Since inception, the Company has been primarily involved in research and development activities. The Company devotes substantially all of its efforts to product research and development, initial market development and raising capital. The Company has not generated any product revenue related to its primary business purpose to date and is subject to a number of risks similar to those of other early stage companies, including dependence on key individuals, competition from other companies, the need for development of commercially viable products and the need to obtain adequate additional financing to fund the development of its product candidates. The Company is also subject to a number of risks similar to other companies in the life sciences industry, including regulatory approval of products, uncertainty of market acceptance of products, competition from substitute products and larger companies, the need to obtain additional financing, compliance with government regulations, protection of proprietary technology, dependence on third parties, product liability and dependence on key individuals.

Reverse Stock Split

On January 12, 2018, the Company effected a one-for-1.2804 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company’s redeemable convertible preferred stock (see Note 8). Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse stock split and adjustment of the preferred stock conversion ratios.

Initial Public Offering

On January 30, 2018, the Company completed its initial public offering (“IPO”), whereby the Company sold 6,516,667 shares of its common stock (inclusive of 850,000 shares of common stock sold by the Company pursuant to the full exercise of an overallotment option granted to the underwriters in connection with the offering) at a price of $15.00 per share. The shares began trading on The Nasdaq Global Select Market on January 26, 2018. The aggregate net proceeds received by the Company from the offering were approximately $89.4 million, after deducting underwriting discounts and commissions and other offering expenses payable by the Company of $8.4 million. Upon the closing of the IPO, all outstanding shares of redeemable convertible preferred stock converted into 15,870,559 shares of common stock and all unvested shares of restricted stock automatically vested. Additionally, the Company is now authorized to issue 150,000,000 shares of common stock and 10,000,000 shares of preferred stock.

Liquidity

In the course of its development activities, the Company has sustained operating losses and expects such losses to continue over the next several years. The Company’s ultimate success depends on the outcome of its research and development activities. The Company has incurred net losses from operations since inception and has an accumulated deficit of $65.6 million as of September 30, 2018. On January 30, 2018, the Company completed its IPO whereby the Company sold 6,516,667 shares of its common stock for aggregate net proceeds of approximately $89.4 million. As of September 30, 2018, the Company had $115.4 million of cash, cash equivalents, and marketable securities, which the Company believes will be sufficient to fund the Company’s current operating plan through at least the next twelve months.