Consolidated Statement of Income - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Sales	$ 46,840	$ 42,294	$ 40,122
Costs, Expenses and Other
Cost of sales	14,112	13,509	12,912
Selling, general and administrative	10,615	10,102	10,074
Research and development	9,872	9,752	10,339
Restructuring costs	638	632	776
Other (income) expense, net	139	(402)	(500)
Total Costs, Expenses and Other	35,376	33,593	33,601
Income Before Taxes	11,464	8,701	6,521
Taxes on Income	1,687	2,508	4,103
Net Income	9,777	6,193	2,418
Less: Net (Loss) Income Attributable to Noncontrolling Interests	(66)	(27)	24
Net Income Attributable to Merck & Co., Inc.	$ 9,843	$ 6,220	$ 2,394
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 3.84	$ 2.34	$ 0.88
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 3.81	$ 2.32	$ 0.87

Total of cost of sales, operating expenses and nonoperating income or expense.

No definition available.

Name:	mrk_CostsExpensesAndOther
Namespace Prefix:	mrk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(a),(d))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227