Pensions and Other Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019
Retirement Plans
Components of net periodic benefit cost
Service cost	$ 323	$ 277	$ 649	$ 553
Interest cost	237	274	477	549
Expected return on plan assets	(608)	(581)	(1,222)	(1,164)
Amortization of prior service cost/(credit)	1	1	1	2
Recognized actuarial losses	222	146	445	290
Curtailments and settlements	0	8	19	7
Net periodic benefit cost	175	125	369	237
Other Benefit Plans
Components of net periodic benefit cost
Service cost	72	69	144	137
Interest cost	33	46	66	92
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of prior service cost/(credit)	(8)	(8)	(16)	(16)
Recognized actuarial losses	35	33	71	65
Curtailments and settlements	0	0	0	0
Net periodic benefit cost	$ 131	$ 139	$ 262	$ 275