Other Intangibles	9 Months Ended
Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Other Intangibles	Other Intangibles In connection with acquisitions, the Company measures the fair value of marketed products and research and development pipeline programs and capitalizes these amounts. See Note 2 for information on intangible assets acquired as a result of business acquisitions in the first nine months of 2017 and 2016. During the first nine months of 2017, the Company recorded an intangible asset impairment charge of $47 million within Materials and production costs related to Intron A, a treatment for certain types of cancers. Sales of Intron A are being adversely affected by the availability of new therapeutic options. During the second quarter, sales of Intron A in the United States eroded more rapidly than previously anticipated by the Company, which led to changes in the cash flow assumptions for Intron A. These revisions to cash flows indicated that the Intron A intangible asset value was not fully recoverable on an undiscounted cash flows basis. The Company utilized market participant assumptions to determine its best estimate of the fair value of the intangible asset related to Intron A that, when compared with its related carrying value, resulted in the impairment charge noted above. The remaining intangible asset value for Intron A at September 30, 2017 was $19 million. During the first nine months of 2016, the Company recorded intangible asset impairment charges related to marketed products of $347 million. Of this amount, $252 million relates to Zontivity, a product for the reduction of thrombotic cardiovascular events in patients with a history of myocardial infarction or with peripheral arterial disease. In March 2016, following several business decisions that reduced sales expectations for Zontivity in the United States and Europe, the Company lowered its cash flow projections for Zontivity. The Company utilized market participant assumptions and considered several different scenarios to determine the fair value of the intangible asset related to Zontivity that, when compared with its related carrying value, resulted in the impairment charge noted above. In addition, the Company wrote-off $95 million that had been capitalized in connection with in-licensed products that, for business reasons, the Company returned to the licensor. Also, during the third quarter and first nine months of 2017, the Company recorded $245 million and $253 million, respectively, of IPR&D impairment charges within Research and development expenses. In the third quarter of 2017, Merck made a strategic decision to discontinue the development of the investigational combination regimens MK-3682B (grazoprevir/ruzasvir/uprifosbuvir) and MK-3682C (ruzasvir/uprifosbuvir) for the treatment of chronic hepatitis C virus (HCV) infection. This decision was made based on a review of available Phase 2 efficacy data and in consideration of the evolving marketplace and the growing number of treatment options available for patients with chronic HCV infection, including Zepatier (elbasvir and grazoprevir), which is currently marketed by the Company for the treatment of chronic HCV infection. As a result of this decision, the Company recorded an IPR&D impairment charge of $240 million in the third quarter and first nine months of 2017 to write-off the intangible asset related to uprifosbuvir. During the first nine months of 2016, the Company recorded $225 million of IPR&D impairment charges. Of this amount, $112 million relates to an in-licensed program that, for business reasons, was returned to the licensor. The remaining IPR&D impairment charges in 2016 primarily relate to deprioritized pipeline programs that were deemed to have no alternative use during the period. The Company may recognize additional non-cash impairment charges in the future related to other marketed products or pipeline programs and such charges could be material.

Other Intangibles

In connection with acquisitions, the Company measures the fair value of marketed products and research and development pipeline programs and capitalizes these amounts. See Note 2 for information on intangible assets acquired as a result of business acquisitions in the first nine months of 2017 and 2016.

During the first nine months of 2017, the Company recorded an intangible asset impairment charge of $47 million within Materials and production costs related to Intron A, a treatment for certain types of cancers. Sales of Intron A are being adversely affected by the availability of new therapeutic options. During the second quarter, sales of Intron A in the United States eroded more rapidly than previously anticipated by the Company, which led to changes in the cash flow assumptions for Intron A. These revisions to cash flows indicated that the Intron A intangible asset value was not fully recoverable on an undiscounted cash flows basis. The Company utilized market participant assumptions to determine its best estimate of the fair value of the intangible asset related to Intron A that, when compared with its related carrying value, resulted in the impairment charge noted above. The remaining intangible asset value for Intron A at September 30, 2017 was $19 million.

During the first nine months of 2016, the Company recorded intangible asset impairment charges related to marketed products of $347 million. Of this amount, $252 million relates to Zontivity, a product for the reduction of thrombotic cardiovascular events in patients with a history of myocardial infarction or with peripheral arterial disease. In March 2016, following several business decisions that reduced sales expectations for Zontivity in the United States and Europe, the Company lowered its cash flow projections for Zontivity. The Company utilized market participant assumptions and considered several different scenarios to determine the fair value of the intangible asset related to Zontivity that, when compared with its related carrying value, resulted in the impairment charge noted above. In addition, the Company wrote-off $95 million that had been capitalized in connection with in-licensed products that, for business reasons, the Company returned to the licensor.

Also, during the third quarter and first nine months of 2017, the Company recorded $245 million and $253 million, respectively, of IPR&D impairment charges within Research and development expenses. In the third quarter of 2017, Merck made a strategic decision to discontinue the development of the investigational combination regimens MK-3682B (grazoprevir/ruzasvir/uprifosbuvir) and MK-3682C (ruzasvir/uprifosbuvir) for the treatment of chronic hepatitis C virus (HCV) infection. This decision was made based on a review of available Phase 2 efficacy data and in consideration of the evolving marketplace and the growing number of treatment options available for patients with chronic HCV infection, including Zepatier (elbasvir and grazoprevir), which is currently marketed by the Company for the treatment of chronic HCV infection. As a result of this decision, the Company recorded an IPR&D impairment charge of $240 million in the third quarter and first nine months of 2017 to write-off the intangible asset related to uprifosbuvir.

During the first nine months of 2016, the Company recorded $225 million of IPR&D impairment charges. Of this amount, $112 million relates to an in-licensed program that, for business reasons, was returned to the licensor. The remaining IPR&D impairment charges in 2016 primarily relate to deprioritized pipeline programs that were deemed to have no alternative use during the period.

The Company may recognize additional non-cash impairment charges in the future related to other marketed products or pipeline programs and such charges could be material.