Pensions and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017
Retirement Plans
Components of net periodic benefit cost
Service cost	$ 309	$ 255	$ 618	$ 506
Interest cost	249	231	501	461
Expected return on plan assets	(554)	(509)	(1,114)	(1,014)
Amortization of prior service cost/(credit)	0	1	1	1
Recognized actuarial losses	213	150	428	302
Curtailments and settlements	0	(1)	(2)	(1)
Net periodic benefit cost	217	127	432	255
Other Benefit Plans
Components of net periodic benefit cost
Service cost	68	62	135	123
Interest cost	38	40	75	79
Expected return on plan assets	(2)	(1)	(4)	(3)
Amortization of prior service cost/(credit)	(8)	(8)	(16)	(15)
Recognized actuarial losses	31	35	61	69
Curtailments and settlements	0	0	0	0
Net periodic benefit cost	$ 127	$ 128	$ 251	$ 253