Shareholders' Equity - Before and after-tax components of other comprehensive income (loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Jan. 02, 2016	Jan. 03, 2015
Pension and postretirement benefits adjustments, pre-tax:
Unrealized gains (losses), pre-tax	$ (382)	$ 136	$ (734)
Amortization of net actuarial loss, pre-tax	104	150	114
Amortization of prior service credit, pre-tax	(7)	(7)	(8)
Recognition of prior service credit, pre-tax	12		18
Pension and postretirement benefits adjustments, net, pre-tax	(273)	279	(610)
Deferred gains (losses) on hedge contracts, pre-tax:
Current deferrals, pre-tax	11	(33)	(16)
Reclassification adjustments, pre-tax	17	19	12
Deferred gains (losses) on hedge contracts, net, pre-tax	28	(14)	(4)
Foreign currency translation adjustments, pre-tax	(36)	(55)	(71)
Other comprehensive income (loss), pre-tax	(281)	210	(685)
Pension and postretirement benefits adjustments, tax:
Unrealized gains (losses), tax	135	(44)	252
Amortization of net actuarial loss, tax	(39)	(53)	(40)
Amortization of prior service credit, tax	4	2	4
Recognition of prior service credit, tax	(5)		(7)
Pension and postretirement benefits adjustments, net, tax	95	(95)	209
Deferred gains (losses) on hedge contracts, tax:
Current deferrals, tax	(4)	7	4
Reclassification adjustments, tax	(4)	(4)	(3)
Deferred gains (losses) on hedge contracts, net, tax	(8)	3	1
Foreign currency translation adjustments, tax	(13)	(10)	(4)
Other comprehensive income (loss), tax	74	(102)	206
Pension and postretirement benefits adjustments, after-tax:
Unrealized gains (losses), after-tax	(247)	92	(482)
Amortization of net actuarial loss, after-tax	65	97	74
Amortization of prior service credit, after-tax	(3)	(5)	(4)
Recognition of prior service credit, after-tax	7		11
Pension and postretirement benefits adjustments, net, after-tax	(178)	184	(401)
Deferred gains (losses) on hedge contracts, after-tax:
Current deferrals, after-tax	7	(26)	(12)
Reclassification adjustments, after-tax	13	15	9
Deferred gains (losses) on hedge contracts, net, after-tax	20	(11)	(3)
Foreign currency translation adjustments, after-tax	(49)	(65)	(75)
Other comprehensive income (loss)	$ (207)	$ 108	$ (479)