Equity Changes in Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Jan. 02, 2016	Jan. 03, 2015
Equity [Abstract]
Net income	$ 695	$ 614	$ 633
Foreign currency translation adjustment before tax	(230)	(170)	(231)
Foreign currency translation adjustments tax (expense) benefit	(24)	(26)	(32)
Foreign currency translation adjustments after tax	(254)	(196)	(263)
Unrealized gain (loss) on cash flow hedges, pre-tax	(55)	8	(35)
Unrealized gain (loss) on cash flow hedges, tax (expense) benefit	22	(3)	18
Unrealized gain (loss) on cash flow hedges, after-tax	(33)	5	(17)
Reclassifications to net income, pre-tax	11	(23)	(10)
Reclassifications to net income, tax (expense) benefit	(6)	3	2
Reclassification to net income, after-tax	5	(20)	(8)
Net experience gain (loss)	0	0	(8)
Net experience gain (loss), tax (expense) benefit	0	0	3
Net experience gain (loss), after tax	0	0	(5)
Prior service credit (cost)	21	63	10
Prior service credit (cost), tax (expense) benefit	(7)	(24)	(3)
Prior service credit (cost), after-tax	14	39	7
Net experience loss, pre-tax	3	3	3
Net experience loss, tax (expense) benefit	(1)	(1)	(1)
Net experience loss, after-tax	2	2	2
Prior service cost	5	9	10
Prior service cost, tax (expense) benefit	(1)	(3)	(3)
Prior service cost, after-tax	4	6	7
Venezuela deconsolidation loss, pre-tax	63	0	0
Venezuela deconsolidation loss, tax (expense) benefit	0	0	0
Venezuela deconsolidation loss related to CTA, net of tax	63	0	0
Other Comprehensive Income (Loss), before Tax	(182)	(110)	(261)
Other Comprehensive Income (Loss), Tax	(17)	(54)	(16)
Other Comprehensive Income (loss)	(199)	(164)	(277)
Comprehensive income	496	450	356
Net income (loss) attributable to noncontrolling interests	1	0	1
Other comprehensive income (loss) attributable to noncontrolling interests	0	(1)	0
Comprehensive income attributable to Kellogg Company	$ 495	$ 451	$ 355