Nature of Business	3 Months Ended
Nature of Business	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business COMPASS Pathways plc, or the Company, is a mental health care company dedicated to accelerating patient access to evidence-based innovation in mental health. The Company is developing psilocybin therapy through late-stage clinical trials in Europe and North America for patients with treatment-resistant depression. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary intellectual property and technology, compliance with government regulations and the ability to secure additional capital to fund operations. Therapeutic candidates currently under development will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s therapeutic development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from sales. The Company has funded its operations primarily with proceeds from the sale of its convertible preferred shares, the issuance of convertible notes, and more recently through the sale of American Depository Shares, or ADSs, in connection with the September 2020 IPO and its $154.8 million May 2021 follow-on offering. On October 8, 2021, the Company entered into a Sales Agreement with Cowen and Company, LLC (“Cowen”), under which the Company may issue and sell from time to time up to $150.0 million of its ADSs, each representing one ordinary share, through Cowen as the sales agent. Sales of the Company’s ADSs, if any, will be made at market prices. The Company has not yet sold any ADSs under this at-the-market offering. The Company has incurred recurring losses since its inception, including net losses of $21.2 million and $12.7 million for the three months ended March 31, 2022 and 2021, respectively. In addition, as of March 31, 2022, the Company had an accumulated deficit of $190.8 million. The Company expects to continue to generate operating losses for the foreseeable future. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations. The Company’s inability to raise capital as and when needed could have a negative impact on its financial condition and ability to pursue its business strategies. There can be no assurance that the current operating plan will be achieved or that additional funding will be available on terms acceptable to the Company, or at all. The Company believes the cash and cash equivalents on hand as of March 31, 2022 of $243.7 million will be sufficient to fund its operating expenses and capital expenditure requirements into 2024. There can be no assurance that the Company will be able to secure debt or equity financing or generate revenue on terms acceptable to the Company, on a timely basis or at all. The failure of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company’s business, results of operations, and financial conditions. The Company continues to assess its business plans and the additional impact which the ongoing COVID-19 pandemic may have on its ability to advance the development and manufacturing of COMP360 as a result of adverse impacts on the research sites, service providers, vendors, or suppliers on whom it relies, or to raise further financing to support the development of its investigational COMP360 psilocybin therapy. While many health measures put in place to attempt to contain the spread of COVID-19 resurgences, including existing or future variants, if any, no assurances can be given that the Company to avoid any future impact from the ongoing COVID-19 pandemic or the emergence of new variants, including downturns in business sentiment generally or in its sector in particular, impacts on global supply chains, or other effects. The Company cannot currently predict the scope and severity of any future potential business shutdowns or disruptions, but if the Company or any of the third parties on whom it relies or with whom the Company conducts business were to experience additional shutdowns or other business disruptions, the Company’s ability to conduct its business in the manner and on the timelines presently planned could be materially and adversely impacted.