Comprehensive Income Statement - USD ($) $ in Millions	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 1,269	$ 695	$ 614
Other comprehensive income (loss), pre-tax:
Foreign currency translation adjustment before tax	(34)	(230)	(170)
Cash flow hedges, pre-tax:
Unrealized gain (loss) on cash flow hedges, pre-tax	0	(55)	8
Reclassifications to net income, pre-tax	9	11	(23)
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Net experience gain (loss)	44	25	0
Prior service credit (cost)	0	(4)	63
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience loss, pre-tax	0	3	3
Prior service cost, pre-tax	1	5	9
Venezuela deconsolidation loss, pre-tax	0	63	0
Other comprehensive income (loss), pre-tax	20	(182)	(110)
Other comprehensive income (loss), tax (expense) benefit:
Foreign currency translation adjustments tax (expense) benefit	113	(24)	(26)
Cash flow hedges, tax (expense) benefit:
Unrealized gain (loss) on cash flow hedges, tax (expense) benefit	0	22	(3)
Reclassifications to net income, tax (expense) benefit	(3)	(6)	3
Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit:
Net experience gain (loss), tax (expense) benefit	(12)	(9)	0
Prior service credit (cost), tax (expense) benefit	0	2	(24)
Postretirement and postemployment benefits reclassification to net income, tax (expense) benefit:
Net experience loss, tax (expense) benefit	0	(1)	(1)
Prior service cost, tax (expense) benefit	0	(1)	(3)
Venezuela deconsolidation loss, tax (expense) benefit	0	0	0
Other comprehensive income (loss), tax (expense) benefit	98	(17)	(54)
Other comprehensive income (loss), after-tax
Foreign currency translation adjustments after tax	79	(254)	(196)
Cash flow hedges, after-tax:
Unrealized gain (loss) on cash flow hedges, after-tax	0	(33)	5
Reclassification to net income, after-tax	6	5	(20)
Postretirement and postemployment benefit amounts arising during the period, after-tax
Net experience gain (loss), after tax	32	16	0
Prior service credit (cost), after-tax	0	(2)	39
Postretirement and postemployment benefits reclassification to net income, after-tax
Net experience loss, after-tax	0	2	2
Prior service cost, after-tax	1	4	6
Venezuela deconsolidation loss related to CTA, net of tax	0	63	0
Other comprehensive income (loss)	118	(199)	(164)
Comprehensive income	1,387	496	450
Net income (loss) attributable to noncontrolling interests	0	1	0
Other comprehensive income (loss) attributable to noncontrolling interests	0	0	(1)
Comprehensive income attributable to Kellogg Company	$ 1,387	$ 495	$ 451