Pensions and other benefit plans - Schedule of Net Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Jan. 01, 2023	Jan. 02, 2022
Amounts Recognized in the Company’s Balance Sheet consist of the following:
Non-current assets	$ 4,992	$ 4,581
Current liabilities	(538)	(593)
Non-current liabilities	(7,149)	(6,542)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Transferred to group annuity contract	800
Retirement Plans
Change in Benefit Obligation
Projected benefit obligation - beginning of year	29,390	41,272
Service cost	893	1,319	$ 1,412
Interest cost	1,437	908	768
Plan participant contributions	73	67
Amendments	(6)	7
Actuarial (gains) losses	2,068	(12,159)
Divestitures & acquisitions	(352)	0
Curtailments, settlements & restructuring	(238)	(7)
Benefits paid from plan	(2,122)	(1,220)
Effect of exchange rates	601	(797)
Projected benefit obligation - end of year	31,744	29,390	41,272
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value — beginning of year	31,496	41,909
Actual return on plan assets	3,951	(8,663)
Company contributions	268	261
Plan participant contributions	73	67
Settlements	(176)	(5)
Divestitures & acquisitions	(509)	0
Benefits paid from plan assets	(2,122)	(1,220)
Effect of exchange rates	626	(853)
Plan assets at fair value - End of year	33,607	31,496	41,909
Funded status - end of year	1,863	2,106
Amounts Recognized in the Company’s Balance Sheet consist of the following:
Non-current assets	4,992	4,581
Current liabilities	(119)	(127)
Non-current liabilities	(3,010)	(2,348)
Total recognized in the consolidated balance sheet — end of year	1,863	2,106
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial loss	4,962	3,948
Prior service cost (credit)	(1,236)	(1,417)
Unrecognized net transition obligation	0	0
Total before tax effects	3,726	2,531
Accumulated Benefit Obligation	30,139	27,797
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax [Abstract]
Net periodic benefit cost (credit)	(676)	(62)	607
Net actuarial (gain) loss	711	(793)
Amortization of net actuarial loss	199	(655)
Prior service cost (credit)	(2)	7
Amortization of prior service (cost) credit	185	183
Effect of exchange rates	103	(140)
Total loss/(income) recognized in other comprehensive income, before tax	1,195	(1,398)
Total recognized in net periodic benefit cost and other comprehensive income	519	(1,460)
Other Benefit Plans
Change in Benefit Obligation
Projected benefit obligation - beginning of year	4,192	4,874
Service cost	264	320	309
Interest cost	214	104	80
Plan participant contributions	0	0
Amendments	0	0
Actuarial (gains) losses	469	(704)
Divestitures & acquisitions	1	0
Curtailments, settlements & restructuring	(332)	0
Benefits paid from plan	(702)	(393)
Effect of exchange rates	2	(9)
Projected benefit obligation - end of year	4,108	4,192	4,874
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value — beginning of year	78	102
Actual return on plan assets	16	(17)
Company contributions	694	386
Plan participant contributions	0	0
Settlements	0	0
Divestitures & acquisitions	0	0
Benefits paid from plan assets	(702)	(393)
Effect of exchange rates	0	0
Plan assets at fair value - End of year	86	78	102
Funded status - end of year	(4,022)	(4,114)
Amounts Recognized in the Company’s Balance Sheet consist of the following:
Non-current assets	0	0
Current liabilities	(416)	(461)
Non-current liabilities	(3,606)	(3,653)
Total recognized in the consolidated balance sheet — end of year	(4,022)	(4,114)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial loss	354	239
Prior service cost (credit)	(6)	(7)
Unrecognized net transition obligation	0
Total before tax effects	348	232
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax [Abstract]
Net periodic benefit cost (credit)	487	533	$ 502
Net actuarial (gain) loss	136	(751)
Amortization of net actuarial loss	(22)	(121)
Prior service cost (credit)	0	0
Amortization of prior service (cost) credit	2	5
Effect of exchange rates	0	(1)
Total loss/(income) recognized in other comprehensive income, before tax	116	(868)
Total recognized in net periodic benefit cost and other comprehensive income	$ 603	$ (335)