Pensions and Other Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Retirement Plans
Components of net periodic benefit cost
Service cost	$ 330	$ 275	$ 979	$ 828
Interest cost	238	273	715	822
Expected return on plan assets	(617)	(578)	(1,839)	(1,742)
Amortization of prior service cost/(credit)	0	1	1	3
Recognized actuarial losses	224	145	669	435
Curtailments and settlements	0	(4)	19	3
Net periodic benefit cost	175	112	544	349
Other Benefit Plans
Components of net periodic benefit cost
Service cost	72	68	216	205
Interest cost	33	46	99	138
Expected return on plan assets	(2)	(2)	(5)	(5)
Amortization of prior service cost/(credit)	(7)	(7)	(23)	(23)
Recognized actuarial losses	36	32	107	97
Curtailments and settlements	0	0	0	0
Net periodic benefit cost	$ 132	$ 137	$ 394	$ 412