CONDENSED CONSOLIDATED STATEMENT OF INCOME - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Sales	$ 12,057	$ 10,816
Costs, Expenses and Other
Cost of sales	3,312	3,052
Selling, general and administrative	2,555	2,425
Research and development	2,209	1,931
Restructuring costs	72	153
Other (income) expense, net	71	188
Total Costs, Expenses and Other	8,219	7,749
Income Before Taxes	3,838	3,067
Taxes on Income	619	205
Net Income	3,219	2,862
Less: Net Loss Attributable to Noncontrolling Interests	0	(53)
Net Income Attributable to Merck & Co., Inc.	$ 3,219	$ 2,915
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.27	$ 1.13
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.26	$ 1.12

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