Equity Equity - Changes in Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 02, 2016	Jan. 03, 2015	Dec. 28, 2013
Equity [Abstract]
Net income	$ 614	$ 633	$ 1,808
Foreign currency translation adjustment before tax	(170)	(231)	(24)
Foreign currency translation adjustments tax (expense) benefit	(26)	(32)	0
Foreign currency translation adjustments after tax	(196)	(263)	(24)
Unrealized gain (loss) on cash flow hedges, pre-tax	8	(35)	11
Unrealized gain (loss) on cash flow hedges, tax (expense) benefit	(3)	18	(1)
Unrealized gain (loss) on cash flow hedges, after-tax	5	(17)	10
Reclassifications to net income, pre-tax	(23)	(10)	(6)
Reclassifications to net income, tax (expense) benefit	3	2	0
Reclassification to net income, after-tax	(20)	(8)	(6)
Net experience gain (loss)	0	(8)	17
Net experience gain (loss), tax (expense) benefit	0	3	(6)
Net experience gain (loss), after tax	0	(5)	11
Prior service credit (cost)	63	10	9
Prior service credit (cost), tax (expense) benefit	(24)	(3)	(2)
Prior service credit (cost), after-tax	39	7	7
Net experience loss, pre-tax	3	3	5
Net experience loss, tax (expense) benefit	(1)	(1)	(2)
Net experience loss, after-tax	2	2	3
Prior service cost	9	10	13
Prior service cost, tax (expense) benefit	(3)	(3)	(4)
Prior service cost, after-tax	6	7	9
Other Comprehensive Income (Loss), before Tax	(110)	(261)	25
Other Comprehensive Income (Loss), Tax	(54)	(16)	(15)
Other Comprehensive Income (loss)	(164)	(277)	10
Comprehensive income	450	356	1,818
Net income (loss) attributable to noncontrolling interests	0	1	1
Other comprehensive income (loss) attributable to noncontrolling interests	(1)	0	0
Comprehensive income attributable to Kellogg Company	$ 451	$ 355	$ 1,817