Retirement Plans - Benefits Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 02, 2017	Jul. 03, 2016	Jul. 02, 2017	Jul. 03, 2016
Defined Benefit Plan Disclosure [Line Items]
Decrease in expected long-term rate-of-return on assets			0.75%
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 42	$ 44	$ 84	$ 88
Interest cost	113	114	226	228
Expected return on plan assets	(170)	(178)	(339)	(356)
Recognized net actuarial loss (gain)	86	84	172	168
Amortization of prior service credit	(16)	(17)	(33)	(34)
Net periodic benefit cost	55	47	110	94
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	2	6	5
Interest cost	9	9	17	17
Expected return on plan assets	(9)	(8)	(17)	(16)
Recognized net actuarial loss (gain)	(1)	(1)	(2)	(2)
Amortization of prior service credit	(1)	(1)	(2)	(3)
Net periodic benefit cost	$ 1	$ 1	$ 2	$ 1