Pensions and Other Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018
Retirement Plans
Components of net periodic benefit cost
Service cost	$ 275	$ 307	$ 828	$ 925
Interest cost	273	247	822	748
Expected return on plan assets	(578)	(550)	(1,742)	(1,664)
Amortization of prior service cost/(credit)	1	1	3	2
Recognized actuarial losses	145	213	435	641
Curtailments and settlements	(4)	0	3	(2)
Net periodic benefit cost	112	218	349	650
Other Benefit Plans
Components of net periodic benefit cost
Service cost	68	67	205	202
Interest cost	46	37	138	112
Expected return on plan assets	(2)	(1)	(5)	(5)
Amortization of prior service cost/(credit)	(7)	(7)	(23)	(23)
Recognized actuarial losses	32	31	97	92
Curtailments and settlements	0	0	0	0
Net periodic benefit cost	$ 137	$ 127	$ 412	$ 378