Acquisitions, Research Collaborations and License Agreements	6 Months Ended
	Jun. 30, 2022
Business Combination and Asset Acquisition [Abstract]
Acquisitions, Research Collaborations and License Agreements	Acquisitions, Research Collaborations and License Agreements The Company continues to pursue acquisitions and the establishment of external alliances such as research collaborations and licensing agreements to complement its internal research capabilities. These arrangements often include upfront payments, as well as expense reimbursements or payments to the third party, and milestone, royalty or profit share arrangements, contingent upon the occurrence of certain future events linked to the success of the asset in development. The Company also reviews its marketed products and pipeline to examine candidates which may provide more value through out-licensing and, as part of its portfolio assessment process, may also divest certain assets. Pro forma financial information for acquired businesses is not presented if the historical financial results of the acquired entity are not significant when compared with the Company’s financial results. In July 2022, Merck and Orion Corporation (Orion) announced a global co-development and co-commercialization agreement for Orion’s investigational candidate ODM-208 (MK-5684) and other drugs targeting cytochrome P450 11A1 (CYP11A1), an enzyme important in steroid production. ODM-208 is an oral, non-steroidal inhibitor of CYP11A1 currently being evaluated in a Phase 2 clinical trial for the treatment of patients with metastatic castration-resistant prostate cancer. Merck made an upfront payment to Orion of $290 million, which will be recorded in Research and development expenses in the third quarter of 2022. Orion will be responsible for the manufacture of clinical and commercial supply of ODM-208. In addition, the contract provides both parties with an option to convert the initial co-development and co-commercialization agreement into a global exclusive license to Merck. If the option is exercised, Merck would assume full responsibility for all past development and commercialization expenses associated with the program since inception of the agreement, as well as all future development and commercialization expenses. In addition, Orion would be eligible to receive milestone payments associated with progress in the development and commercialization of ODM-208 as well as tiered double-digit royalties on sales if the product is approved. Also in July 2022, Merck and Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (Kelun-Biotech) closed a license and collaboration agreement in which Merck gained exclusive worldwide rights for the development, manufacture and commercialization of an investigational antibody drug conjugate (ADC) (MK-1200) for the treatment of solid tumors. Under the terms of the agreement, Merck and Kelun-Biotech will collaborate on the early clinical development of the investigational ADC. Merck will make an upfront payment of $35 million, which will be recorded in Research and development expenses in the third quarter of 2022. Kelun-Biotech is also eligible to receive future contingent milestone payments aggregating up to $82 million in developmental milestones, $334 million in regulatory milestones, and $485 million in sales-based milestones. The agreement also provides for Merck to pay tiered royalties ranging from a mid-single-digit rate to a low-double-digit rate on future net sales. In May 2022, in connection with an existing arrangement, Merck exercised its option to obtain an exclusive license outside of China for the development, manufacture and commercialization of Kelun-Biotech’s trophoblast antigen 2 (TROP2)-targeting ADC programs, including its lead compound, SKB-264 (MK-2870). SKB-264 is currently being evaluated in Phase 2 trials for non-small-cell lung cancer and advanced solid tumors. Under the terms of the agreement, Merck and Kelun-Biotech will collaborate on certain early clinical development plans, including evaluating the potential of SKB-264 as a monotherapy and in combination with Keytruda (pembrolizumab) for advanced solid tumors. Upon option exercise, Merck made a payment of $30 million, which was recorded in Research and development expenses in the second quarter of 2022, and agreed to make additional payments of $30 million upon completion of specified project activities and $25 million upon technology transfer. Merck also agreed to make quarterly payments in 2022 and 2023 aggregating $101 million to fund Kelun-Biotech’s ongoing research and development activities. In addition, Kelun-Biotech is eligible to receive future contingent milestone payments (which includes all program compounds) aggregating up to $90 million in developmental milestones, $290 million in first commercial sale milestones, and $780 million in sales-based milestones. The agreement also provides for Merck to pay tiered royalties ranging from a mid-single-digit rate to a low-double-digit rate on future net sales. In April 2021, Merck acquired Pandion Therapeutics, Inc. (Pandion), a clinical-stage biotechnology company developing novel therapeutics designed to address the unmet needs of patients living with autoimmune diseases. Pandion is advancing a pipeline of precision immune modulators targeting critical immune control nodes. Total consideration paid of $1.9 billion included $147 million of transaction costs primarily comprised of share-based compensation payments to settle equity awards. The transaction was accounted for as an acquisition of an asset. Merck recorded net assets of $156 million (primarily cash) and Research and development expenses of $1.7 billion in the second quarter and first six months of 2021 related to the transaction. There are no future contingent payments associated with the acquisition. In January 2021, Merck entered into an exclusive license and research collaboration agreement with Artiva Biotherapeutics, Inc. (Artiva) to discover, develop and manufacture CAR-NK cells that target certain solid tumors using Artiva’s proprietary platform. Merck and Artiva agreed to engage in up to three different research programs, each covering a collaboration target. Merck has sole responsibility for all development and commercialization activities (including regulatory filing and approval). Under the terms of the agreement, Merck made an upfront payment of $30 million, which was included in Research and development expenses in the first six months of 2021, for license and other rights for the first two collaboration targets and agreed to make another upfront payment of $15 million for license and other rights for the third collaboration target when it is selected by Merck and accepted by Artiva. In addition, Artiva is eligible to receive future contingent milestone payments (which span all three collaboration targets), aggregating up to: $217.5 million in developmental milestones, $570 million in regulatory milestones, and $1.05 billion in sales-based milestones. The agreement also provides for Merck to pay tiered royalties ranging from 7% to 14% on future sales. As part of Merck’s 2020 acquisition of OncoImmune, Merck obtained MK-7110, a therapeutic candidate that was being evaluated for the treatment of patients hospitalized with COVID-19. In 2021, Merck received feedback from the U.S. Food and Drug Administration (FDA) that additional data would be needed to support a potential Emergency Use Authorization application and therefore the Company did not expect MK-7110 would become available until the first half of 2022. Given this timeline and the technical, clinical and regulatory uncertainties, the availability of a number of medicines for patients hospitalized with COVID-19, and the need to concentrate Merck’s resources on accelerating the development and manufacture of the most viable therapeutics and vaccines, Merck decided to discontinue development of MK-7110 for the treatment of COVID-19. Due to the discontinuation, the Company recorded charges of $37 million and $207 million in the second quarter and first six months of 2021, respectively, which are reflected in Cost of sales and relate to fixed assets and materials written off, as well as the recognition of liabilities for purchase commitments.