Pensions and other benefit plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2024	Dec. 31, 2023	Jan. 01, 2023
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	$ 5,800
Projected benefit obligation, unfunded plans	6,100	6,100
Plan with accumulated benefit obligation in excess of plan assets, plan assets	3,200	3,100
Fair value of company's common stock directly held in plan assets	13	14
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	33,395	33,607	$ 31,496
Other Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	93	86	$ 78
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plans	122
International Plans
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plans	107
Commingled funds | Level 2 | Other Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	$ 93	$ 86
Maximum | Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Retirement plan benefits employee compensation period	5 years