Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 04, 2015	Jun. 28, 2014	Jul. 04, 2015	Jun. 28, 2014	Jan. 03, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 222	$ 295	$ 449	$ 701	$ 633
Other comprehensive income (loss), pre-tax:
Foreign currency translation adjustments, pre-tax	9	30	(54)	33
Cash flow hedges, pre-tax:
Unrealized gain (loss) on cash flow hedges, pre-tax	(4)	(23)	4	(24)
Reclassification to net income, pre-tax	(3)	(1)	(7)	(11)
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Prior service credit (cost), pre-tax	1	(9)	0	(9)
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience loss	1	1	2	2
Prior service cost	2	4	5	6
Other comprehensive income (loss), pre-tax	6	2	(50)	(3)
Other comprehensive income (loss), tax (expense) benefit
Foreign currency translation adjustments, tax (expense) benefit	5	0	(16)	0
Cash flow hedges, tax (expense) benefit:
Unrealized gain (loss) on cash flow hedges, tax (expense) benefit	0	7	(1)	7
Reclassification to net income, tax (expense) benefit	0	0	0	3
Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit:
Prior service credit (cost), tax (expense) benefit	0	3	0	3
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)	(1)	(2)	(2)
Other comprehensive income (loss), tax (expense) benefit	4	9	(19)	11
Other comprehensive income (loss), after tax:
Foreign currency translation adjustments, after-tax	14	30	(70)	33
Cash flow hedges, after tax
Unrealized gain (loss) on cash flow hedges, after-tax	(4)	(16)	3	(17)
Reclassification to net income, after-tax	(3)	(1)	(7)	(8)
Postretirement and postemployment benefit amounts arising during the period, after-tax:
Prior service credit (cost), after-tax	1	(6)	0	(6)
Postretirement and postemployment benefits reclassification to net income, after-tax:
Net experience loss, after-tax	1	1	2	2
Prior service cost, after-tax	1	3	3	4
Other comprehensive income (loss)	10	11	(69)	8
Comprehensive income	232	306	380	709
Net income (loss) attributable to noncontrolling interests	(1)	$ 0	(1)	$ 0
Other comprehensive income (loss) attributable to noncontrolling interests	0		(1)
Comprehensive income attributable to Kellogg Company	$ 233		$ 382