CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 4,745	$ 3,248	$ 1,591	$ 11,502
Other Comprehensive Loss Net of Taxes:
Net unrealized gain on derivatives, net of reclassifications	159	338	171	584
Benefit plan net (loss) gain and prior service (cost) credit, net of amortization	0	(186)	(75)	92
Cumulative translation adjustment	(175)	(568)	(244)	(990)
Other comprehensive income (loss), net of taxes	(16)	(416)	(148)	(314)
Comprehensive Income Attributable to Merck & Co., Inc.	$ 4,729	$ 2,832	$ 1,443	$ 11,188