Nature of the Business and Basis of Presentation	9 Months Ended
Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business and Basis of Presentation	1. Nature of the business and basis of presentation Viela Bio, Inc. (“Viela” or the “Company”) is a clinical-stage biotechnology research and development company pioneering and advancing treatments for severe inflammation and autoimmune diseases by selectively targeting shared critical pathways that are the root cause of disease. The Company was incorporated on December 11, 2017 under the laws of the State of Delaware. From December 11, 2017 to December 31, 2017 the Company had no substantive operations. In February 2018, pursuant to an Asset Purchase Agreement (the “Asset Purchase Agreement”) with MedImmune, LLC, MedImmune Limited (collectively, “MedImmune”), and AstraZeneca Collaboration Ventures, LLC (“AZ”, and, together with MedImmune, the “AZ Parties”), the Company acquired intellectual property and the biological, regulatory and other materials associated with a portfolio of clinical and pre-clinical molecules, for a purchase price of approximately $142,253 financed by AZ’s purchase of the Company’s Series A preferred stock. Following the asset purchase, the Company entered into several agreements with AZ and MedImmune, including a license agreement, sublicense agreements, a transition services agreement, a clinical supply agreement and a commercial supply agreement. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, ability to secure additional capital to fund operations, completion and success of clinical testing, compliance with applicable governmental regulations, development by competitors of new technological innovations, dependence on key personnel and protection of proprietary technology. Drug candidates currently under development will require extensive clinical testing prior to regulatory approval and commercialization. These efforts require significant amounts of additional capital, adequate personnel, and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s drug development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. In October, 2019, the Company completed an initial public offering (the “IPO”) of its common stock and issued and sold 7,900,000 shares of common stock at a public offering price of $19.00 per share, resulting in gross proceeds of $150,100 and net proceeds of $136,266 after deducting underwriting discounts and commissions and offering expenses of approximately $13,834. In addition, and contemporaneously with the closing of the issuance and sale of the aforementioned shares, the Company issued and sold an additional 1,185,000 shares of common stock, pursuant to the full exercise of the underwriter’s option to purchase additional shares, for gross proceeds of $22,515 and net proceeds of $20,939 after deducting underwriting discounts and commissions of $1,576. Thus, the aggregate gross proceeds to the Company from the IPO were $172,615 and net proceeds after deducting underwriting discounts and commissions and other offering costs, were $157,205. Upon the closing of the IPO, the outstanding shares of series A redeemable convertible preferred stock (the “Series A Preferred Stock”), and series B redeemable convertible preferred stock (the “Series B Preferred Stock” and together with the Series A Preferred Stock, the “Preferred Stock”) converted into an aggregate of 40,618,706 shares of common stock. Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). All adjustments necessary for the fair presentation of the Company’s financial statements have been presented. The accompanying balance sheet as of September 30, 2019, the related statements of operations and comprehensive loss and redeemable convertible preferred stock and stockholders’ deficit for the three and nine months ended September 30, 2019 and 2018, and the statements of cash flows for the nine months ended September 30, 2019 and 2018 and related footnote disclosures are unaudited. All adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the accompanying interim balance sheet, statements of operations and comprehensive loss, redeemable convertible preferred stock and stockholders’ deficit and cash flows have been made. The results for the nine months ended September 30, 2019 and 2018, are not necessarily indicative of results to be expected for the year ending December 31, 2019, any other interim periods or any future year or period.

Nature of the Business and Basis of Presentation

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of the Business and Basis of Presentation

1. Nature of the business and basis of presentation

Viela Bio, Inc. (“Viela” or the “Company”) is a clinical-stage biotechnology research and development company pioneering and advancing treatments for severe inflammation and autoimmune diseases by selectively targeting shared critical pathways that are the root cause of disease. The Company was incorporated on December 11, 2017 under the laws of the State of Delaware. From December 11, 2017 to December 31, 2017 the Company had no substantive operations.

In February 2018, pursuant to an Asset Purchase Agreement (the “Asset Purchase Agreement”) with MedImmune, LLC, MedImmune Limited (collectively, “MedImmune”), and AstraZeneca Collaboration Ventures, LLC (“AZ”, and, together with MedImmune, the “AZ Parties”), the Company acquired intellectual property and the biological, regulatory and other materials associated with a portfolio of clinical and pre-clinical molecules, for a purchase price of approximately $142,253 financed by AZ’s purchase of the Company’s Series A preferred stock. Following the asset purchase, the Company entered into several agreements with AZ and MedImmune, including a license agreement, sublicense agreements, a transition services agreement, a clinical supply agreement and a commercial supply agreement.

The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, ability to secure additional capital to fund operations, completion and success of clinical testing, compliance with applicable governmental regulations, development by competitors of new technological innovations, dependence on key personnel and protection of proprietary technology. Drug candidates currently under development will require extensive clinical testing prior to regulatory approval and commercialization. These efforts require significant amounts of additional capital, adequate personnel, and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s drug development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

In October, 2019, the Company completed an initial public offering (the “IPO”) of its common stock and issued and sold 7,900,000 shares of common stock at a public offering price of $19.00 per share, resulting in gross proceeds of $150,100 and net proceeds of $136,266 after deducting underwriting discounts and commissions and offering expenses of approximately $13,834. In addition, and contemporaneously with the closing of the issuance and sale of the aforementioned shares, the Company issued and sold an additional 1,185,000 shares of common stock, pursuant to the full exercise of the underwriter’s option to purchase additional shares, for gross proceeds of $22,515 and net proceeds of $20,939 after deducting underwriting discounts and commissions of $1,576. Thus, the aggregate gross proceeds to the Company from the IPO were $172,615 and net proceeds after deducting underwriting discounts and commissions and other offering costs, were $157,205. Upon the closing of the IPO, the outstanding shares of series A redeemable convertible preferred stock (the “Series A Preferred Stock”), and series B redeemable convertible preferred stock (the “Series B Preferred Stock” and together with the Series A Preferred Stock, the “Preferred Stock”) converted into an aggregate of 40,618,706 shares of common stock.

Basis of Presentation

The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). All adjustments necessary for the fair presentation of the Company’s financial statements have been presented.

The accompanying balance sheet as of September 30, 2019, the related statements of operations and comprehensive loss and redeemable convertible preferred stock and stockholders’ deficit for the three and nine months ended September 30, 2019 and 2018, and the statements of cash flows for the nine months ended September 30, 2019 and 2018 and related footnote disclosures are unaudited. All adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the accompanying interim balance sheet, statements of operations and comprehensive loss, redeemable convertible preferred stock and stockholders’ deficit and cash flows have been made. The results for the nine months ended September 30, 2019 and 2018, are not necessarily indicative of results to be expected for the year ending December 31, 2019, any other interim periods or any future year or period.