CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net (Loss) Income Attributable to Merck & Co., Inc.	$ (5,975)	$ 3,944	$ (3,154)	$ 8,254
Other Comprehensive (Loss) Income Net of Taxes:
Net unrealized gain on derivatives, net of reclassifications	145	183	12	246
Benefit plan net (loss) gain and prior service (cost) credit, net of amortization	(25)	246	(75)	278
Cumulative translation adjustment	(137)	(387)	(69)	(422)
Other comprehensive income (loss), net of taxes	(17)	42	(132)	102
Comprehensive (Loss) Income Attributable to Merck & Co., Inc.	$ (5,992)	$ 3,986	$ (3,286)	$ 8,356