Employee Benefits - Components of Plan Benefit Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 04, 2015	Jun. 28, 2014	Jul. 04, 2015	Jun. 28, 2014
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 28	$ 27	$ 56	$ 53
Interest cost	53	56	106	113
Expected return on plan assets	(100)	(105)	(200)	(209)
Amortization of unrecognized prior service cost (credit)	3	4	6	7
Total plan benefit (income) expense	(16)	(18)	(32)	(36)
Other Nonpension Postretirement
Defined Benefit Plan Disclosure [Line Items]
Service cost	9	7	17	14
Interest cost	13	13	25	27
Expected return on plan assets	(25)	(25)	(50)	(49)
Amortization of unrecognized prior service cost (credit)	(1)	0	(1)	(1)
Total plan benefit (income) expense	(4)	(5)	(9)	(9)
Postemployment
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	2	3	4
Interest cost	1	1	2	2
Recognized net loss	1	1	2	2
Total plan benefit (income) expense	$ 3	$ 4	$ 7	$ 8