Description of Business	9 Months Ended
Description of Business	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Amicus Therapeutics, Inc. (the "Company") is a global, patient-dedicated biotechnology company focused on discovering, developing, and delivering novel medicines for rare diseases. The Company has a portfolio of product opportunities led by the first, oral monotherapy for Fabry disease that has achieved widespread global approval, a differentiated biologic for Pompe disease that is under review with the U.S. Food and Drug Administration ("FDA"), and an industry leading rare disease gene therapy portfolio. The cornerstone of the Company's portfolio is Galafold® (also referred to as "migalastat"), the first and only approved oral precision medicine for people living with Fabry disease who have amenable genetic variants. Migalastat is currently approved under the trade name Galafold® in the United States ("U.S."), European Union ("E.U."), United Kingdom ("U.K."), and Japan, with multiple additional approvals granted and applications pending in several additional geographies around the world. The lead biologics program of the Company's pipeline is Amicus Therapeutics GAA ("AT-GAA", also known as ATB200/AT2221, or cipaglucosidase alfa/miglustat), a novel, two-component, potential best-in-class treatment for Pompe disease. In February 2019, the FDA granted Breakthrough Therapy designation ("BTD") to AT-GAA for the treatment of late-onset Pompe disease. In September 2021, the FDA set the Prescription Drug User Fee Act ("PDUFA") target action date of May 29, 2022 for the New Drug Application ("NDA") for miglustat and July 29, 2022 for the Biologics License Application ("BLA") for cipaglucosidase alfa. The Company has established an industry leading gene therapy portfolio of potential therapies for people living with rare metabolic diseases, through a license with Nationwide Children's Hospital ("Nationwide Children's") and a research collaboration with the University of Pennsylvania ("Penn"). The Company's pipeline includes gene therapy programs in rare, neurologic/neuromuscular diseases lysosomal disorders ("LDs"), specifically: CLN6 Batten disease ("CLN6"), CLN3 Batten disease ("CLN3"), and CLN1 Batten disease ("CLN1"), Pompe disease, Fabry disease, CDKL5 deficiency disorder ("CDD"), Mucopolysaccharidosis Type IIIB ("MPSIIIB"), as well as a next generation program in Mucopolysaccharidosis Type IIIA ("MPSIIIA"). In the first quarter of 2020, the FDA granted Fast Track designation to the CLN3 gene therapy, AT-GTX-502, for the treatment of pediatric patients less than 18 years of age. In September 2020 and February 2021, the European Medicines Agency granted Priority Medicines designation and the FDA granted Fast Track Designation, respectively, to the CLN6 gene therapy, AT-GTX-501, for the treatment of patients with variant late infantile neuronal ceroid lipofuscinosis 6 ("vLINCL6"). The research collaboration with Penn also provides the Company with exclusive disease-specific access and option rights to develop potentially disruptive new gene therapy platform technologies and programs for most LDs and a broader portfolio of more prevalent rare diseases, including Rett Syndrome, Angelman Syndrome, Myotonic Dystrophy, and select other muscular dystrophies. In September 2021, the Company announced its intent to launch a next-generation genetic medicine company, Caritas Therapeutics, Inc. (“Caritas”) through a definitive business combination agreement pursuant to which the Amicus gene therapy business will be acquired by ARYA Sciences Acquisition Corp IV ("ARYA"), a special purpose acquisition company (or "SPAC"), sponsored by Perceptive Advisors. Concurrent with the closing of the transaction, the Company and Caritas will enter into a co-development and commercialization agreement (the “Co-Development and Collaboration Agreement”) pursuant to which, among other things, (i) the Company and Caritas will collaborate in the research and development of gene therapy product candidates for the treatment of Fabry disease and Pompe diseases, (ii) Caritas will grant the Company an exclusive license under Caritas’ intellectual property to clinically develop and commercialize certain existing and future gene therapy candidates and (iii) Caritas will grant the Company a right of first negotiation for the Company to negotiate an exclusive license to develop and commercialize therapeutic products incorporating gene therapy technologies being developed by Caritas for certain muscular dystrophy indications, in each case, subject to the terms and conditions therein. The Company and Caritas will also enter into a transition services agreement pursuant to which, among other things, (i) the Company and/or one or more of its affiliates will provide certain transitional services to Caritas and/or one or more of its affiliates and (ii) Caritas and/or one or more its affiliates will provide certain transitional services to the Company and/or one or more of its affiliates, in each case, in order to facilitate the orderly transition of the Company’s gene therapy business to Caritas. Concurrent with the closing of the transaction, the Company will enter into the tax receivable agreement with Caritas, ARYA and the other persons from time to time that become a party thereto (such other persons and the Company, collectively, the “TRA Participants”). Pursuant to the tax receivable agreement, ARYA will be required to pay the TRA Participants 85% of the amount of savings, if any, in U.S. federal, state and local income tax that ARYA actually realizes (computed using certain simplifying assumptions) as a result of the increases in tax basis related to any exchanges of Units for Caritas Common Stock. All such payments to the TRA Participants will be ARYA’s obligation, and not that of Caritas. The business combination agreement and the transactions contemplated thereby were unanimously approved by the respective boards of directors of the Company and ARYA. The transaction is expected to close in late 2021 or early 2022, following the approval of the transaction by ARYA’s stockholders and the fulfillment of other customary closing conditions. Prior to the closing, all expenses will continue to be reported within the Company's Consolidated Statements of Operations. Following the close of the transaction, Amicus will become the largest stockholder of Caritas with an approximate 36% ownership stake (assuming no redemptions by ARYA’s stockholders), through transfer of assets constituting the Company's gene therapy business and contributing $50 million in exchange for a number of units of Caritas as an equity investment. As of September 30, 2021, the Company will continue to fully consolidate the gene therapy business until the close of the transaction and has not applied accounting treatment under the "held for sale" guidance due to the conditional regulatory and stockholder approvals. Additionally, in September 2021, the Company entered into securities purchase agreements with certain investors for the private placement of an aggregate of 11,296,660 shares of the Company's common stock, at a purchase price of $10.18 per share and pre-funded warrants to purchase an aggregate of 8,349,705 shares of common stock, at a purchase price of $10.17 per pre-funded warrant. The net proceeds from these private placements were approximately $199.8 million. The Company expects to use the net proceeds to further fund initiatives in the global commercialization of Galafold® and the anticipated global launch of AT-GAA and, in connection with the business combination, to invest $50 million in cash in Caritas. The Company's operations have not been significantly impacted by the novel coronavirus (“COVID-19”) pandemic thus far. However, the Company continued to observe periodic increase in lag times between patient identification and Galafold® initiation due to the resurgence of COVID-19 into 2021. The Company has maintained operations in all geographies, secured its global supply chain for its commercial and clinical products, and maintained the operational integrity of its clinical trials, with minimal disruption. The Company believes its ability to continue to operate without any significant disruptions will depend on the continued health of its employees, the ongoing demand for Galafold® and the continued operation of its global supply chain. The Company has continued to provide uninterrupted access to medicines for those in need of treatment, while prioritizing the health and safety of its global workforce. However, the Company's results of operations in future periods may be negatively impacted by unknown future impacts from the COVID-19 pandemic. The Company had an accumulated deficit of $2.2 billion as of September 30, 2021 and anticipates incurring losses through the fiscal year ending December 31, 2021 and beyond. The Company has historically funded its operations through stock offerings, Galafold® revenues, debt issuances, collaborations, and other financing arrangements. Based on the current operating model, the Company believes that the current cash position, which includes expected revenues, and net proceeds from the September 2021 private placement of securities, is sufficient to fund the Company's operations and ongoing research programs to achieve self-sustainability. Potential impacts of the COVID-19 pandemic, business development collaborations, pipeline expansion, and investment in manufacturing capabilities could impact the Company's future capital requirements.