Retirement Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2016	Oct. 03, 2015	Oct. 01, 2016	Oct. 03, 2015
Pension Benefits
Net periodic benefit cost (credit)
Service cost	$ 25	$ 27	$ 74	$ 86
Interest cost	84	82	254	245
Expected return on plan assets	(123)	(121)	(368)	(363)
Amortization of prior service cost (credit)	4	4	11	12
Amortization of net actuarial loss	26	35	78	113
Curtailment and other charges				6
Net periodic benefit cost (credit)	16	27	49	99
Postretirement Benefits Other Than Pensions
Net periodic benefit cost (credit)
Service cost	1	1	2	3
Interest cost	4	4	12	12
Amortization of prior service cost (credit)	(6)	(6)	(17)	(18)
Amortization of net actuarial loss		$ 1		1
Net periodic benefit cost (credit)	$ (1)		$ (3)	$ (2)