Employee Benefits - Components of Plan Benefit Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 02, 2016	Jul. 04, 2015	Jul. 02, 2016	Jul. 04, 2015
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 25	$ 28	$ 49	$ 56
Interest cost	44	53	88	106
Expected return on plan assets	(90)	(100)	(179)	(200)
Amortization of unrecognized prior service cost (credit)	4	3	7	6
Total plan benefit (income) expense	(17)	(16)	(35)	(32)
Other Nonpension Postretirement
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	9	10	17
Interest cost	9	13	19	25
Expected return on plan assets	(23)	(25)	(45)	(50)
Amortization of unrecognized prior service cost (credit)	(2)	(1)	(5)	(1)
Total plan benefit (income) expense	(11)	(4)	(21)	(9)
Postemployment
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	1	4	3
Interest cost	1	1	2	2
Recognized net loss	1	1	2	2
Total plan benefit (income) expense	$ 4	$ 3	$ 8	$ 7