Pensions and other benefit plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Jan. 01, 2023	Jan. 02, 2022
Defined Benefit Plan Disclosure [Line Items]
Percentage of corridor of greater of market value of assets	10.00%
Accumulated benefit obligation unfunded plans	$ 5,800	$ 2,700
Projected benefit obligation, unfunded plans	6,100	2,700
Plan with accumulated benefit obligation in excess of plan assets, plan assets	3,100	300
Fair value of company's common stock directly held in plan assets	$ 14	$ 21
Percentage of company's common stock to plan asset	0.00%	0.10%
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	$ 33,607	$ 31,496	$ 41,909
Other Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	86	78	$ 102
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plans	135
International Plans
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plans	133
Commingled funds | Level 2 | Other Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	$ 86	$ 78
Maximum | Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Retirement plan benefits employee compensation period	5 years