Nature of the Business and Liquidity	12 Months Ended
Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business and Liquidity	1. Nature of the Business and Liquidity Orchard Therapeutics plc (the “Company”) is a global gene therapy company dedicated to transforming the lives of people affected by severe diseases through the development of innovative, potentially curative gene therapies. The Company’s ex vivo autologous hematopoietic stem cell (“HSC”) gene therapy approach utilizes genetically modified blood stem cells and seeks to correct the underlying cause of disease in a single administration. The Company has a portfolio that includes a commercial-stage product and research and development-stage product candidates. The Company is a public limited company incorporated pursuant to the laws of England and Wales. The Company has American Depositary Shares (“ADSs”) registered with the U.S. Securities and Exchange Commission (the “SEC”). The ADSs were listed on the Nasdaq Global Select Market on October 31, 2018 and were transferred to the Nasdaq Capital Market on September 13, 2022. As of December 31, 2022, each holder of ordinary shares and ADSs is entitled to one vote per ordinary share and to receive dividends when and if such dividends are recommended by the board of directors and declared by the shareholders. The Company did not declared any dividends in 2022 or 2021. Effective March 10, 2023, the Company enacted a ratio change wherein each ADS listed on the Nasdaq Capital Market is worth ten ordinary shares. On February 9, 2021, the Company issued and sold (i) 20,900,321 ordinary shares, nominal value £0.10 per share, at a purchase price of $6.22 per share (the “Purchase Price”), which was the closing sale price of the Company’s ADSs on the Nasdaq Global Select Market on February 4, 2021, and (ii) 3,215,434 non-voting ordinary shares, nominal value £0.10 per share, at the Purchase Price (together (i) and (ii) the “2021 Private Placement”). The 2021 Private Placement resulted in net proceeds to the Company of $143.6 million after deducting placement agent fees of $6.0 million and other issuance costs of $0.4 million. As of December 31, 2021, all outstanding non-voting shares have been converted to voting ordinary shares. In January 2022, the Company began to generate revenue from product sales of Libmeldy™ in Europe following the approval of Libmeldy by the European Commission in December 2020 for the treatment of early onset metachromatic leukodystrophy (“MLD”), characterized by biallelic mutations in the arylsulfatase-A ("ARSA") gene leading to a reduction of the ARSA enzymatic activity in children with (i) late infantile or early juvenile forms, without clinical manifestations of the disease, or (ii) the early juvenile form, with early clinical manifestations of the disease, who still have the ability to walk independently and before the onset of cognitive decline. On March 6, 2023, the Company entered into a Securities Purchase Agreement pursuant to which the Company agreed to sell ordinary shares, non-voting ordinary shares, and warrants to purchase to purchase ordinary shares or non-voting ordinary shares in an unregisterd offering (the "2023 Private Placement"). The 2023 Private Placement consists of two closings. On March 10, 2023, the Company completed the initial closing and issued and sold (i) 56,666,900 ordinary shares and non-voting ordinary shares, nominal value £0.10 per share and (ii) warrants to purchase an aggregate of 62,333,590 ordinary shares or non-voting ordinary shares, at a purchase price of $6.00 per unit, where each unit consists of ten (10) Shares and an accompanying Warrant to purchase eleven (11) Shares. The initial closing of the 2023 Private Placement resulted in gross proceeds of approximately $34.0 million. Refer to Footnote 19 for further discussion around the 2023 Private Placement. The Company’s business is subject to risks and uncertainties common to development-stage companies in the biotechnology industry. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s technology will be obtained, that any products developed will obtain necessary government regulatory approval or that any products, if approved, will be commercially viable. The Company operates in an environment of rapid technological innovation and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees, consultants and service providers. Even if the Company’s product development efforts are successful in gaining regulatory approval, it is uncertain when, if ever, the Company will realize significant revenue from product sales. The future developments of the COVID-19 pandemic may also directly or indirectly impact the Company’s business, including impacts due to travel restrictions, supply chain disruptions, business closures, and other measures. Through December 31, 2022, the Company funded its operations with proceeds from the sale of equity securities, including ADSs in the Company’s initial public offering (“IPO”) and follow-on offering, ordinary shares in the private placement, and convertible preferred shares. The Company has also financed its operations through proceeds from the Company’s senior term facilities agreement with MidCap Financial (Ireland) Limited, research grants from the California Institute of Regenerative Medicine (“CIRM”), upfront payments from the Company’s collaboration agreement and share purchase agreement with Pharming Group N.V., proceeds from the sales of the Company's Libmeldy product, and reimbursements associated with two UK research and development tax relief programs, the Small and Medium-sized Enterprises research and development tax credit (“SME”) program and the Research and Development Expenditure (“RDEC”) program. The Company has incurred recurring losses since its inception and expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash, cash equivalents, and marketable securities on hand as of December 31, 2022, of $143.8 million, together with expected proceeds from sales of Libmeldy and the $34 million received in March 2023 from the 2023 Private Placement, will be sufficient to fund its operations and capital expenditure requirements for at least twelve months from the date of filing of this Annual Report on Form 10-K. The Company will seek additional funding through private or public equity financings, debt financings, collaborations, strategic alliances, and marketing, distribution or licensing arrangements. The Company may not be able to obtain financing on acceptable terms, or at all, and may not be able to enter into collaborations or other arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company's stockholders. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations. If the Company is unable to obtain funding, the Company will be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.

Nature of the Business and Liquidity

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

1. Nature of the Business and Liquidity

Orchard Therapeutics plc (the “Company”) is a global gene therapy company dedicated to transforming the lives of people affected by severe diseases through the development of innovative, potentially curative gene therapies. The Company’s ex vivo autologous hematopoietic stem cell (“HSC”) gene therapy approach utilizes genetically modified blood stem cells and seeks to correct the underlying cause of disease in a single administration. The Company has a portfolio that includes a commercial-stage product and research and development-stage product candidates.

The Company is a public limited company incorporated pursuant to the laws of England and Wales. The Company has American Depositary Shares (“ADSs”) registered with the U.S. Securities and Exchange Commission (the “SEC”). The ADSs were listed on the Nasdaq Global Select Market on October 31, 2018 and were transferred to the Nasdaq Capital Market on September 13, 2022. As of December 31, 2022, each holder of ordinary shares and ADSs is entitled to one vote per ordinary share and to receive dividends when and if such dividends are recommended by the board of directors and declared by the shareholders. The Company did not declared any dividends in 2022 or 2021.

Effective March 10, 2023, the Company enacted a ratio change wherein each ADS listed on the Nasdaq Capital Market is worth ten ordinary shares.

On February 9, 2021, the Company issued and sold (i) 20,900,321 ordinary shares, nominal value £0.10 per share, at a purchase price of $6.22 per share (the “Purchase Price”), which was the closing sale price of the Company’s ADSs on the Nasdaq Global Select Market on February 4, 2021, and (ii) 3,215,434 non-voting ordinary shares, nominal value £0.10 per share, at the Purchase Price (together (i) and (ii) the “2021 Private Placement”). The 2021 Private Placement resulted in net proceeds to the Company of $143.6 million after deducting placement agent fees of $6.0 million and other issuance costs of $0.4 million. As of December 31, 2021, all outstanding non-voting shares have been converted to voting ordinary shares.

In January 2022, the Company began to generate revenue from product sales of Libmeldy™ in Europe following the approval of Libmeldy by the European Commission in December 2020 for the treatment of early onset metachromatic leukodystrophy (“MLD”), characterized by biallelic mutations in the arylsulfatase-A ("ARSA") gene leading to a reduction of the ARSA enzymatic activity in children with (i) late infantile or early juvenile forms, without clinical manifestations of the disease, or (ii) the early juvenile form, with early clinical manifestations of the disease, who still have the ability to walk independently and before the onset of cognitive decline.

On March 6, 2023, the Company entered into a Securities Purchase Agreement pursuant to which the Company agreed to sell ordinary shares, non-voting ordinary shares, and warrants to purchase to purchase ordinary shares or non-voting ordinary shares in an unregisterd offering (the "2023 Private Placement"). The 2023 Private Placement consists of two closings. On March 10, 2023, the Company completed the initial closing and issued and sold (i) 56,666,900 ordinary shares and non-voting ordinary shares, nominal value £0.10 per share and (ii) warrants to purchase an aggregate of 62,333,590 ordinary shares or non-voting ordinary shares, at a purchase price of $6.00 per unit, where each unit consists of ten (10) Shares and an accompanying Warrant to purchase eleven (11) Shares. The initial closing of the 2023 Private Placement resulted in gross proceeds of approximately $34.0 million. Refer to Footnote 19 for further discussion around the 2023 Private Placement.

The Company’s business is subject to risks and uncertainties common to development-stage companies in the biotechnology industry. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s technology will be obtained, that any products developed will obtain necessary government regulatory approval or that any products, if approved, will be commercially viable. The Company operates in an environment of rapid technological innovation and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees, consultants and service providers. Even if the Company’s product development efforts are successful in gaining regulatory approval, it is uncertain when, if ever, the Company will realize significant revenue from product sales. The future developments of the COVID-19 pandemic may also directly or indirectly impact the Company’s business, including impacts due to travel restrictions, supply chain disruptions, business closures, and other measures.

Through December 31, 2022, the Company funded its operations with proceeds from the sale of equity securities, including ADSs in the Company’s initial public offering (“IPO”) and follow-on offering, ordinary shares in the private placement, and convertible preferred shares. The Company has also financed its operations through proceeds from the Company’s senior term facilities agreement with MidCap Financial (Ireland) Limited, research grants from the California Institute of Regenerative Medicine (“CIRM”), upfront payments from the Company’s collaboration agreement and share purchase agreement with Pharming Group N.V., proceeds from the sales of the Company's Libmeldy product, and reimbursements associated with two UK research and development tax relief programs, the Small and Medium-sized Enterprises research and

development tax credit (“SME”) program and the Research and Development Expenditure (“RDEC”) program. The Company has incurred recurring losses since its inception and expects to continue to generate operating losses for the foreseeable future.

The Company expects that its cash, cash equivalents, and marketable securities on hand as of December 31, 2022, of $143.8 million, together with expected proceeds from sales of Libmeldy and the $34 million received in March 2023 from the 2023 Private Placement, will be sufficient to fund its operations and capital expenditure requirements for at least twelve months from the date of filing of this Annual Report on Form 10-K. The Company will seek additional funding through private or public equity financings, debt financings, collaborations, strategic alliances, and marketing, distribution or licensing arrangements. The Company may not be able to obtain financing on acceptable terms, or at all, and may not be able to enter into collaborations or other arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company's stockholders. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations. If the Company is unable to obtain funding, the Company will be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.