Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 02, 2016	Jul. 04, 2015	Jul. 02, 2016	Jul. 04, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 280	$ 222	$ 455	$ 449
Other comprehensive income (loss), pre-tax:
Foreign currency translation adjustments, pre-tax	(48)	9	(103)	(54)
Cash flow hedges, pre-tax:
Unrealized gain (loss) on cash flow hedges, pre-tax	(3)	(4)	(60)	4
Reclassification to net income, pre-tax	6	(3)	8	(7)
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Prior service credit (cost), pre-tax	(1)	1	(1)	0
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience loss	1	1	2	2
Prior service cost	2	2	2	5
Other comprehensive income (loss), pre-tax	(43)	6	(152)	(50)
Other comprehensive income (loss), tax (expense) benefit
Foreign currency translation adjustments, tax (expense) benefit	(16)	5	13	(16)
Cash flow hedges, tax (expense) benefit:
Unrealized gain (loss) on cash flow hedges, tax (expense) benefit	1	0	24	(1)
Reclassification to net income, tax (expense) benefit	(2)	0	(3)	0
Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit:
Prior service credit (cost), tax (expense) benefit	0	0	0	0
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)		(2)
Other comprehensive income (loss), tax (expense) benefit	(17)	4	34	(19)
Other comprehensive income (loss), after tax:
Foreign currency translation adjustments, after-tax	(64)	14	(90)	(70)
Cash flow hedges, after tax
Unrealized gain (loss) on cash flow hedges, after-tax	(2)	(4)	(36)	3
Reclassification to net income, after-tax	4	(3)	5	(7)
Postretirement and postemployment benefit amounts arising during the period, after-tax:
Prior service credit (cost), after-tax	(1)	1	(1)	0
Postretirement and postemployment benefits reclassification to net income, after-tax:
Net experience loss, after-tax	1	1	2	2
Prior service cost, after-tax	2	1	2	3
Other comprehensive income (loss)	(60)	10	(118)	(69)
Comprehensive income	220	232	337	380
Net income (loss) attributable to noncontrolling interests	0	(1)	0	(1)
Other comprehensive income (loss) attributable to noncontrolling interests		0		(1)
Comprehensive income attributable to Kellogg Company	$ 220	$ 233	$ 337	$ 382