Consolidated Statement of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Sales	$ 59,283	$ 48,704	$ 41,518
Costs, Expenses and Other
Cost of sales	17,411	13,626	13,618
Selling, general and administrative	10,042	9,634	8,955
Research and development	13,548	12,245	13,397
Restructuring costs	337	661	575
Other (income) expense, net	1,501	(1,341)	(890)
Total costs, expenses and other	42,839	34,825	35,655
Income from Continuing Operations Before Taxes	16,444	13,879	5,863
Taxes on Income from Continuing Operations	1,918	1,521	1,340
Net Income from Continuing Operations	14,526	12,358	4,523
Less: Net Income Attributable to Noncontrolling Interests	7	13	4
Net Income from Continuing Operations Attributable to Merck & Co., Inc.	14,519	12,345	4,519
Income from Discontinued Operations, Net of Taxes and Amounts Attributable to Noncontrolling Interests	0	704	2,548
Net Income Attributable to Merck & Co., Inc.	$ 14,519	$ 13,049	$ 7,067
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders
Income from Continuing Operations (in dollars per share)	$ 5.73	$ 4.88	$ 1.79
Income from Discontinued Operations (in dollars per share)	0	0.28	1.01
Net Income (in dollars per share)	5.73	5.16	2.79
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders
Income from Continuing Operations (in dollars per share)	5.71	4.86	1.78
Income from Discontinued Operations (in dollars per share)	0	0.28	1.00
Net Income (in dollars per share)	$ 5.71	$ 5.14	$ 2.78