The Company and Basis of Presentation	9 Months Ended
Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
The Company and Basis of Presentation	1. The Company and Basis of Presentation Aeglea BioTherapeutics, Inc. (“Aeglea” or the “Company”) is a clinical-stage biotechnology company committed to developing enzyme-based therapeutics in the field of amino acid metabolism to treat rare genetic diseases and cancer. The Company was formed as a Limited Liability Company (LLC) in Delaware on December 16, 2013 under the name Aeglea BioTherapeutics Holdings, LLC and was converted from a Delaware LLC to a Delaware corporation (the “LLC Conversion”) on March 10, 2015. The Company operates in one segment and has its principal offices in Austin, Texas. Stock Offerings Initial Public Offering In April 2016, the Company’s Registration Statement on Form S-1 (File No. 333-205001) relating to the initial public offering (“IPO”) of its common stock was declared effective by the Securities and Exchange Commission (“SEC”). The IPO closed on April 12, 2016, and 5,481,940 shares of common stock were sold at a public offering price of $10.00 per share, including 481,940 shares of common stock issued upon the partial exercise by the underwriters of their option to purchase additional shares. The Company received $47.3 million in aggregate cash proceeds, net of underwriting discounts and commissions of $3.8 million and offering costs of $3.7 million incurred by the Company. Immediately prior to the closing of the IPO, all shares of outstanding convertible preferred stock were automatically converted, at a ratio of one share of common stock for each share of convertible preferred stock, into 7,172,496 shares of common stock with the related carrying value of $58.3 million reclassified to common stock and additional paid-in capital. In connection with the IPO, the Company amended its Restated Certificate of Incorporation to change the authorized capital stock to 510,000,000 shares of which 500,000,000 shares are designated as common stock and 10,000,000 shares are designated as preferred stock, all with a par value of $0.0001 per share. There are no shares of preferred stock outstanding as of September 30, 2017. Follow-on Public Offering In June 2017, the Company issued and sold 3,000,000 shares of common stock in an underwritten public offering pursuant to a shelf registration statement on Form S-3 at a public offering price of $4.10 per share. The net proceeds to the Company from this public offering was approximately $11.4 million, after deducting underwriting discounts and commissions of $615,000 and offering costs of $306,000. As of September 30, 2017, the Company did not have any offering costs recorded as an outstanding liability on the balance sheet. Liquidity As of September 30, 2017, the Company had working capital of $54.6 million, an accumulated deficit of $66.0 million, and cash, cash equivalents, and marketable securities of $55.7 million. The Company has not generated any product revenues and has not achieved profitable operations. There is no assurance that profitable operations will ever be achieved, and, if achieved, could be sustained on a continuing basis. In addition, development activities, clinical and nonclinical testing, and commercialization of the Company’s products will require significant additional financing. The Company is subject to a number of risks similar to other life science companies, including, but not limited to, risks related to the successful discovery and development of product candidates, raising additional capital, development of competing drugs and therapies, protection of proprietary technology and market acceptance of the Company’s products. As a result of these and other factors and the related uncertainties, there can be no assurance of the Company’s future success. Based upon the Company’s current operating plan, the Company believes that it has sufficient resources to fund operations through September 30, 2019 with its existing cash, cash equivalents, and marketable securities. The Company will need to secure additional funding in the future, in order to carry out all of its planned research and development activities. If the Company is unable to obtain additional financing or generate license or product revenue, the lack of liquidity could have a material adverse effect on the Company’s future prospects. Unaudited Interim Financial Information The interim condensed consolidated financial statements included in this document are unaudited. The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for a fair statement of the Company’s financial position as of September 30, 2017, and its results of operations for the three and nine months ended September 30, 2017, and cash flows for the nine months ended September 30, 2017 and 2016. The results of operations for nine months ended September 30, 2017 are not necessarily indicative of the results to be expected for the year ending December 31, 2017 or for any other future annual or interim period. The December 31, 2016 balance sheet was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States (“U.S. GAAP”). These financial statements should be read in conjunction with the audited financial statements included in the Company’s Form 10-K for the year ended December 31, 2016 as filed with the SEC.

1. The Company and Basis of Presentation

Aeglea BioTherapeutics, Inc. (“Aeglea” or the “Company”) is a clinical-stage biotechnology company committed to developing enzyme-based therapeutics in the field of amino acid metabolism to treat rare genetic diseases and cancer. The Company was formed as a Limited Liability Company (LLC) in Delaware on December 16, 2013 under the name Aeglea BioTherapeutics Holdings, LLC and was converted from a Delaware LLC to a Delaware corporation (the “LLC Conversion”) on March 10, 2015. The Company operates in one segment and has its principal offices in Austin, Texas.

Stock Offerings

Initial Public Offering

In April 2016, the Company’s Registration Statement on Form S-1 (File No. 333-205001) relating to the initial public offering (“IPO”) of its common stock was declared effective by the Securities and Exchange Commission (“SEC”). The IPO closed on April 12, 2016, and 5,481,940 shares of common stock were sold at a public offering price of $10.00 per share, including 481,940 shares of common stock issued upon the partial exercise by the underwriters of their option to purchase additional shares. The Company received $47.3 million in aggregate cash proceeds, net of underwriting discounts and commissions of $3.8 million and offering costs of $3.7 million incurred by the Company.

Immediately prior to the closing of the IPO, all shares of outstanding convertible preferred stock were automatically converted, at a ratio of one share of common stock for each share of convertible preferred stock, into 7,172,496 shares of common stock with the related carrying value of $58.3 million reclassified to common stock and additional paid-in capital.

In connection with the IPO, the Company amended its Restated Certificate of Incorporation to change the authorized capital stock to 510,000,000 shares of which 500,000,000 shares are designated as common stock and 10,000,000 shares are designated as preferred stock, all with a par value of $0.0001 per share. There are no shares of preferred stock outstanding as of September 30, 2017.

Follow-on Public Offering

In June 2017, the Company issued and sold 3,000,000 shares of common stock in an underwritten public offering pursuant to a shelf registration statement on Form S-3 at a public offering price of $4.10 per share. The net proceeds to the Company from this public offering was approximately $11.4 million, after deducting underwriting discounts and commissions of $615,000 and offering costs of $306,000. As of September 30, 2017, the Company did not have any offering costs recorded as an outstanding liability on the balance sheet.

Liquidity

As of September 30, 2017, the Company had working capital of $54.6 million, an accumulated deficit of $66.0 million, and cash, cash equivalents, and marketable securities of $55.7 million. The Company has not generated any product revenues and has not achieved profitable operations. There is no assurance that profitable operations will ever be achieved, and, if achieved, could be sustained on a continuing basis. In addition, development activities, clinical and nonclinical testing, and commercialization of the Company’s products will require significant additional financing.

The Company is subject to a number of risks similar to other life science companies, including, but not limited to, risks related to the successful discovery and development of product candidates, raising additional capital, development of competing drugs and therapies, protection of proprietary technology and market acceptance of the Company’s products. As a result of these and other factors and the related uncertainties, there can be no assurance of the Company’s future success.

Based upon the Company’s current operating plan, the Company believes that it has sufficient resources to fund operations through September 30, 2019 with its existing cash, cash equivalents, and marketable securities. The Company will need to secure additional funding in the future, in order to carry out all of its planned research and development activities. If the Company is unable to obtain additional financing or generate license or product revenue, the lack of liquidity could have a material adverse effect on the Company’s future prospects.

Unaudited Interim Financial Information

The interim condensed consolidated financial statements included in this document are unaudited. The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for a fair statement of the Company’s financial position as of September 30, 2017, and its results of operations for the three and nine months ended September 30, 2017, and cash flows for the nine months ended September 30, 2017 and 2016. The results of operations for nine months ended September 30, 2017 are not necessarily indicative of the results to be expected for the year ending December 31, 2017 or for any other future annual or interim period. The December 31, 2016 balance sheet was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States (“U.S. GAAP”). These financial statements should be read in conjunction with the audited financial statements included in the Company’s Form 10-K for the year ended December 31, 2016 as filed with the SEC.