Employee Benefits - Components of Plan Benefit Expense (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jul. 01, 2017	Apr. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 25		$ 25	$ 50	$ 49
Interest cost	42		44	83	88
Expected return on plan assets	(90)		(90)	(180)	(179)
Amortization of unrecognized prior service (gain)	2		4	4	7
Recognized net (gain) loss	(2)	$ 3	0	1	0
Curtailment loss	(3)	1	0	(2)	0
Total plan benefit (income) expense	(26)		(17)	(44)	(35)
Other Nonpension Postretirement
Defined Benefit Plan Disclosure [Line Items]
Service cost	4		5	9	10
Interest cost	9		9	18	19
Expected return on plan assets	(25)		(23)	(49)	(45)
Amortization of unrecognized prior service (gain)	(2)		(2)	(4)	(5)
Recognized net (gain) loss	0	(29)	0	(29)	0
Curtailment loss	0	$ 3	0	3	0
Total plan benefit (income) expense	(14)		(11)	(52)	(21)
Postemployment
Defined Benefit Plan Disclosure [Line Items]
Service cost	2		2	3	4
Interest cost	1		1	2	2
Recognized net (gain) loss	0		1	1	2
Total plan benefit (income) expense	$ 3		$ 4	$ 6	$ 8