Segments of Business and Geographic Areas - Schedule of Segment Reporting By Geographic Area (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2023 USD ($)	Oct. 01, 2023 USD ($)	Jul. 02, 2023 USD ($)	Apr. 02, 2023 USD ($)	Jan. 01, 2023 USD ($)	Oct. 02, 2022 USD ($)	Jul. 03, 2022 USD ($)	Apr. 03, 2022 USD ($)	Dec. 31, 2023 USD ($) segment	Jan. 01, 2023 USD ($)	Jan. 02, 2022 USD ($) Segment
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers	$ 21,395	$ 21,351	$ 21,519	$ 20,894	$ 19,939	$ 19,996	$ 20,215	$ 19,840	$ 85,159	$ 79,990	$ 78,740
Net assets divested	0				27,237				0	27,237
Assets	167,558				187,378				$ 167,558	187,378
Number of segments									2		3
Equity securities, FV-NI, gain (loss)		600							$ (400)
Restructuring									489	275	$ 209
Gain (loss) related to litigation settlement									100
Research and development in process									313	783	$ 900
Property, Plant and Equipment
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	19,898				17,982				19,898	17,982
Other Intangible Assets
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	70,733				74,536				70,733	74,536
bermekimab | In Process Research and Development
Revenues from External Customers and Long-Lived Assets [Line Items]
Impairment of intangible assets, excluding goodwill								600		$ 800
Baby Powder | Talc
Revenues from External Customers and Long-Lived Assets [Line Items]
Loss contingency, loss in period				6,900					$ 7,000
Wholesaler 1 | Sales Revenue, Net | Wholesaler Concentration Risk
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk (as a percent)									18.20%	18.90%	16.60%
Wholesaler 2 | Sales Revenue, Net | Wholesaler Concentration Risk
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk (as a percent)									15.10%	15.00%	12.60%
Wholesaler 3 | Sales Revenue, Net | Wholesaler Concentration Risk
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk (as a percent)									14.20%	13.80%	12.60%
Innovative Medicine
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers	13,722	13,893	13,731	13,413	13,163	13,214	13,317	12,869	$ 54,759	$ 52,563	$ 51,680
Restructuring										100	100
Marketable securities, realized gain (loss)	400	400							(400)	(700)	500
Gain (loss) related to litigation settlement									100
Gain (loss) on divestiture									(200)		600
Litigation expense										100	600
Innovative Medicine | Momenta
Revenues from External Customers and Long-Lived Assets [Line Items]
Impairment of intangible assets, excluding goodwill									200
MedTech
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers	7,673	$ 7,458	$ 7,788	$ 7,481	6,776	$ 6,782	$ 6,898	$ 6,971	30,400	27,427	27,060
Restructuring										300	300
Acquisition costs, period cost									200	300
Regulation charge									300	300	200
Litigation expense										600	100
Research and development in process											900
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers									46,444	41,981	40,640
United States | Innovative Medicine
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers									31,169	28,604	27,954
United States | MedTech
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers									15,275	13,377	12,686
Operating Segments
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers									85,159	79,990	78,740
Long-Lived Assets	89,439				91,437				89,439	91,437
Restructuring									798
Operating Segments | Innovative Medicine
Revenues from External Customers and Long-Lived Assets [Line Items]
Assets	58,324				58,436				58,324	58,436
Supplies expense					800				700	1,500
Restructuring									479
Operating Segments | MedTech
Revenues from External Customers and Long-Lived Assets [Line Items]
Assets	74,710				70,956				74,710	70,956
Restructuring									319
Operating Segments | United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers									46,444	41,981	40,640
Long-Lived Assets	54,832				58,750				54,832	58,750
Operating Segments | Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers									20,410	20,664	20,595
Long-Lived Assets	31,616				29,878				31,616	29,878
Operating Segments | Western Hemisphere excluding U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers									4,549	4,108	3,927
Long-Lived Assets	1,491				1,289				1,491	1,289
Operating Segments | Asia-Pacific, Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales to Customers									13,756	13,237	$ 13,578
Long-Lived Assets	1,500				1,520				1,500	1,520
Corporate, Non-Segment
Revenues from External Customers and Long-Lived Assets [Line Items]
Other non long-lived assets	76,927				67,623				76,927	67,623
Corporate, Non-Segment | General Corporate
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	1,192				1,081				1,192	1,081
Assets	$ 34,524				$ 30,749				$ 34,524	$ 30,749