CONDENSED CONSOLIDATED STATEMENT OF INCOME - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Sales	$ 11,760	$ 10,465	$ 22,575	$ 20,502
Costs, Expenses and Other
Cost of sales	3,401	3,417	6,453	6,601
Selling, general and administrative	2,712	2,508	5,138	5,016
Research and development	2,189	2,274	4,119	5,470
Restructuring costs	59	228	212	323
Other (income) expense, net	140	(48)	327	(340)
Total Costs, Expenses and Other	8,501	8,379	16,249	17,070
Income Before Taxes	3,259	2,086	6,326	3,432
Taxes on Income	615	370	820	975
Net Income	2,644	1,716	5,506	2,457
Less: Net (Loss) Income Attributable to Noncontrolling Interests	(26)	9	(79)	14
Net Income Attributable to Merck & Co., Inc.	$ 2,670	$ 1,707	$ 5,585	$ 2,443
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.04	$ 0.64	$ 2.17	$ 0.91
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.03	$ 0.63	$ 2.15	$ 0.90

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