Consolidated Statement of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Sales	$ 64,168	$ 60,115	$ 59,283
Costs, Expenses and Other
Cost of sales	15,193	16,126	17,411
Selling, general and administrative	10,816	10,504	10,042
Research and development	17,938	30,531	13,548
Restructuring costs	309	599	337
Other (income) expense, net	(24)	466	1,501
Total costs, expenses and other	44,232	58,226	42,839
Income Before Taxes	19,936	1,889	16,444
Taxes on Income	2,803	1,512	1,918
Net Income	17,133	377	14,526
Less: Net Income Attributable to Noncontrolling Interests	16	12	7
Net Income Attributable to Merck & Co., Inc.	$ 17,117	$ 365	$ 14,519
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 6.76	$ 0.14	$ 5.73
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 6.74	$ 0.14	$ 5.71