Pensions and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2017	Oct. 02, 2016	Oct. 01, 2017	Oct. 02, 2016
Retirement Plans
Components of net periodic benefit cost
Service cost	$ 266	$ 224	$ 772	$ 676
Interest cost	232	232	693	698
Expected return on plan assets	(514)	(490)	(1,528)	(1,475)
Amortization of prior service cost/(credit)	1	2	2	2
Recognized actuarial losses	154	123	456	371
Curtailments and settlements	2	6	1	11
Net periodic benefit cost	141	97	396	283
Other Benefit Plans
Components of net periodic benefit cost
Service cost	62	56	185	166
Interest cost	40	39	119	118
Expected return on plan assets	(2)	(1)	(5)	(4)
Amortization of prior service cost/(credit)	(8)	(9)	(23)	(25)
Recognized actuarial losses	34	33	103	101
Curtailments and settlements	0	0	0	0
Net periodic benefit cost	$ 126	$ 118	$ 379	$ 356