Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2016	Oct. 03, 2015	Oct. 01, 2016	Oct. 03, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 292	$ 205	$ 747	$ 654
Other comprehensive income (loss), pre-tax:
Foreign currency translation adjustments, pre-tax	(20)	(88)	(123)	(142)
Cash flow hedges, pre-tax:
Unrealized gain (loss) on cash flow hedges, pre-tax	3	7	(57)	11
Reclassification to net income, pre-tax	0	(7)	8	(14)
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Prior service credit (cost), pre-tax	0	66	(1)	66
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience loss	1	1	3	3
Prior service cost	1	2	3	7
Other comprehensive income (loss), pre-tax	(15)	(19)	(167)	(69)
Other comprehensive income (loss), tax (expense) benefit
Foreign currency translation adjustments, tax (expense) benefit	7	5	20	(11)
Cash flow hedges, tax (expense) benefit:
Unrealized gain (loss) on cash flow hedges, tax (expense) benefit	(1)	(2)	23	(3)
Reclassification to net income, tax (expense) benefit	(1)	1	(4)	1
Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit:
Prior service credit (cost), tax (expense) benefit	0	(25)	0	(25)
Postretirement and postemployment benefits reclassification to net income, tax (expense) benefit:
Net experience loss, tax (expense) benefit	0	0	0	0
Prior service cost, tax (expense) benefit	(1)	0	(1)	(2)
Other comprehensive income (loss), tax (expense) benefit	4	(21)	38	(40)
Other comprehensive income (loss), after tax:
Foreign currency translation adjustments, after-tax	(13)	(83)	(103)	(153)
Cash flow hedges, after tax
Unrealized gain (loss) on cash flow hedges, after-tax	2	5	(34)	8
Reclassification to net income, after-tax	(1)	(6)	4	(13)
Postretirement and postemployment benefit amounts arising during the period, after-tax:
Prior service credit (cost), after-tax	0	41	(1)	41
Postretirement and postemployment benefits reclassification to net income, after-tax:
Net experience loss, after-tax	1	1	3	3
Prior service cost, after-tax	0	2	2	5
Other comprehensive income (loss)	(11)	(40)	(129)	(109)
Comprehensive income	281	165	618	545
Net income (loss) attributable to noncontrolling interests	0	0	0	(1)
Other comprehensive income (loss) attributable to noncontrolling interests	0	1	0	0
Comprehensive income attributable to Kellogg Company	$ 281	$ 164	$ 618	$ 546