CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Jan. 01, 2022	Jan. 02, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 962	$ 1,495	$ 1,264
Foreign currency translation adjustments, pre-tax:
Foreign currency translation adjustment before tax	(412)	(222)	(76)
Net investment hedges gain (loss), pre-tax:
Net investment hedge gain (loss), pre-tax	287	236	(329)
Cash flow hedges, pre-tax:
Net deferred gain (loss) on cash flow hedges, pre-tax	221	38	(9)
Reclassifications to net income, pre-tax	(2)	22	14
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Net experience gain (loss)	5	(2)	(4)
Prior service credit (cost)	(3)	(18)	(21)
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience (gain) loss, pre-tax	(2)	(2)	(3)
Prior service (credit) cost, pre-tax	1	0	(1)
Available-for-sale securities, pre-tax
Unrealized gain (loss) on available-for-sale securities, pre-tax	(5)	(1)	3
Reclassification to net income on available-for-sale securities, pre-tax	1	(2)	0
Other comprehensive income (loss), pre-tax	91	49	(426)
Foreign Currency Translation Adjustment, tax (expense) benefit:
Foreign currency translation adjustments tax (expense) benefit	3	5	(3)
Net Investment Hedges, tax (expense) benefit
Net investment hedges gain (loss), tax (expense) benefit	(72)	(62)	87
Cash flow hedges, tax (expense) benefit:
Net deferred gain (loss) on cash flow hedges, tax (expense) benefit	(57)	(10)	2
Reclassification to net income, tax (expense) benefit	1	(6)	(4)
Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit:
Net experience gain (loss), tax (expense) benefit	(1)	1	1
Prior service credit (cost), tax (expense) benefit	1	4	6
Postretirement and postemployment benefits reclassification to net income, tax (expense) benefit:
Net experience (gain) loss, tax (expense) benefit	1	0	1
Prior service (credit) cost, tax (expense) benefit	0	0	0
Available-for-sale securities, tax (expense) benefit
Unrealized gain (loss) on available-for-sale securities, tax (expense) benefit	0	0	0
Reclassification to net income on available-for-sale securities, tax (expense) benefit	0	0	0
Other comprehensive income (loss), tax (expense) benefit	(124)	(68)	90
Foreign currency translation adjustments, after tax:
Foreign currency translation adjustments after tax	(409)	(217)	(79)
Net Investment Hedges, after tax:
Net investment hedges gain (loss), after-tax	215	174	(242)
Cash flow hedges, after-tax:
Net deferred gain (loss) on cash flow hedges, after-tax	164	28	(7)
Reclassification to net income, after-tax	(1)	16	10
Postretirement and postemployment benefit amounts arising during the period, after-tax
Net experience gain (loss), after tax	4	(1)	(3)
Prior service credit (cost), after-tax	(2)	(14)	(15)
Postretirement and postemployment benefits reclassification to net income, after-tax
Net experience loss, after-tax	(1)	(2)	(2)
Prior service cost, after-tax	1	0	(1)
Available-for-sale securities, after-tax
Unrealized gain (loss) on available-for-sale securities, after-tax	(5)	(1)	3
Reclassification to net income on available-for-sale securities, after-tax	1	(2)	0
Other comprehensive income (loss)	(33)	(19)	(336)
Comprehensive income	929	1,476	928
Net income (loss) attributable to noncontrolling interests	2	7	13
Other comprehensive income (loss) attributable to noncontrolling interests	(46)	(30)	(52)
Comprehensive income attributable to Kellogg Company	$ 973	$ 1,499	$ 967