Retirement Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Pension Benefits
Net periodic benefit cost (credit)
Service cost	$ 25	$ 24
Interest cost	80	85
Expected return on plan assets	(126)	(123)
Amortization of prior service cost (credit)	4	4
Amortization of net actuarial loss	34	26
Net periodic benefit cost (credit)	17	16
Postretirement Benefits Other Than Pensions
Net periodic benefit cost (credit)
Service cost	1	1
Interest cost	3	4
Amortization of prior service cost (credit)	(2)	(6)
Net periodic benefit cost (credit)	$ 2	$ (1)