Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 03, 2015	Sep. 27, 2014	Oct. 03, 2015	Sep. 27, 2014	Jan. 03, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 205	$ 225	$ 654	$ 926	$ 633
Other comprehensive income (loss), pre-tax:
Foreign currency translation adjustments, pre-tax	(88)	(87)	(142)	(54)
Cash flow hedges, pre-tax:
Unrealized gain (loss) on cash flow hedges, pre-tax	7	(2)	11	(26)
Reclassification to net income, pre-tax	(7)	0	(14)	(11)
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Prior service credit (cost), pre-tax	66	19	66	10
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience loss	1	1	3	3
Prior service cost	2	2	7	8
Other comprehensive income (loss), pre-tax	(19)	(67)	(69)	(70)
Other comprehensive income (loss), tax (expense) benefit
Foreign currency translation adjustments, tax (expense) benefit	5	(17)	(11)	(17)
Cash flow hedges, tax (expense) benefit:
Unrealized gain (loss) on cash flow hedges, tax (expense) benefit	(2)	4	(3)	11
Reclassification to net income, tax (expense) benefit	1	0	1	3
Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit:
Prior service credit (cost), tax (expense) benefit	(25)	(7)	(25)	(4)
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	0	(1)	(2)	(3)
Other comprehensive income (loss), tax (expense) benefit	(21)	(21)	(40)	(10)
Other comprehensive income (loss), after tax:
Foreign currency translation adjustments, after-tax	(83)	(104)	(153)	(71)
Cash flow hedges, after tax
Unrealized gain (loss) on cash flow hedges, after-tax	5	2	8	(15)
Reclassification to net income, after-tax	(6)	0	(13)	(8)
Postretirement and postemployment benefit amounts arising during the period, after-tax:
Prior service credit (cost), after-tax	41	12	41	6
Postretirement and postemployment benefits reclassification to net income, after-tax:
Net experience loss, after-tax	1	1	3	3
Prior service cost, after-tax	2	1	5	5
Other comprehensive income (loss)	(40)	(88)	(109)	(80)
Comprehensive income	165	137	545	846
Net income (loss) attributable to noncontrolling interests	0	$ 1	(1)	$ 1
Other comprehensive income (loss) attributable to noncontrolling interests	1		0
Comprehensive income attributable to Kellogg Company	$ 164		$ 546