Retirement Plans - Net periodic benefit cost (credit) and other changes in plan assets and benefit obligations recognized in OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Other changes in plan assets and benefit obligations recognized in OCI
Current year actuarial loss (gain)	$ (18)	$ 382	$ (136)
Amortization of net actuarial gain (loss)	(136)	(104)	(150)
Amortization of prior service credit (cost)	(7)	7	7
Pension Benefits
Net periodic benefit cost (credit)
Service cost	100	98	113
Interest cost	323	338	327
Expected return on plan assets	(507)	(490)	(483)
Amortization of prior service cost (credit)	15	15	16
Amortization of net actuarial loss (gain)	137	104	148
Curtailment and other charges			6
Net periodic benefit cost (credit)	68	65	127
Other changes in plan assets and benefit obligations recognized in OCI
Current year actuarial loss (gain)	(11)	399	(107)
Current year prior service cost (credit)	1
Amortization of net actuarial gain (loss)	(137)	(104)	(148)
Amortization of prior service credit (cost)	(15)	(15)	(18)
Total recognized in OCI, before taxes	(162)	280	(273)
Total recognized in net periodic benefit cost (credit) and OCI	(94)	345	(146)
Postretirement Benefits Other than Pensions
Net periodic benefit cost (credit)
Service cost	3	3	4
Interest cost	12	16	15
Amortization of prior service cost (credit)	(8)	(22)	(25)
Amortization of net actuarial loss (gain)	(1)		2
Net periodic benefit cost (credit)	6	(3)	(4)
Other changes in plan assets and benefit obligations recognized in OCI
Current year actuarial loss (gain)	(7)	(17)	(29)
Current year prior service cost (credit)		(12)
Amortization of net actuarial gain (loss)	1		(2)
Amortization of prior service credit (cost)	8	22	25
Total recognized in OCI, before taxes	2	(7)	(6)
Total recognized in net periodic benefit cost (credit) and OCI	$ 8	$ (10)	$ (10)