Consolidated Statement of Equity - USD ($) $ in Millions	Total	Common Stock	Other Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Non- controlling Interests
Beginning balance at Dec. 31, 2019	$ 26,001	$ 1,788	$ 39,660	$ 46,602	$ (6,193)	$ (55,950)	$ 94
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Merck & Co., Inc.	7,067			7,067
Other comprehensive income (loss), net of taxes	(441)				(441)
Cash dividends declared on common stock	(6,307)			(6,307)
Treasury stock shares purchased	(1,281)					(1,281)
Net income attributable to noncontrolling interests	15						15
Distributions attributable to noncontrolling interests	(22)						(22)
Share-based compensation plans and other	372		(72)			444
Ending balance at Dec. 31, 2020	25,404	1,788	39,588	47,362	(6,634)	(56,787)	87
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Merck & Co., Inc.	13,049			13,049
Other comprehensive income (loss), net of taxes	1,756				1,756
Cash dividends declared on common stock	(6,715)			(6,715)
Treasury stock shares purchased	(840)					(840)
Spin-off of Organon & Co.	5,091		4,643		449		(1)
Net income attributable to noncontrolling interests	16						16
Distributions attributable to noncontrolling interests	(29)						(29)
Share-based compensation plans and other	525		7			518
Ending balance at Dec. 31, 2021	38,257	1,788	44,238	53,696	(4,429)	(57,109)	73
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Merck & Co., Inc.	14,519			14,519
Other comprehensive income (loss), net of taxes	(339)				(339)
Cash dividends declared on common stock	(7,134)			(7,134)
Spin-off of Organon & Co.					449
Net income attributable to noncontrolling interests	7						7
Distributions attributable to noncontrolling interests	(13)						(13)
Share-based compensation plans and other	761		141			620
Ending balance at Dec. 31, 2022	$ 46,058	$ 1,788	$ 44,379	$ 61,081	$ (4,768)	$ (56,489)	$ 67