CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 30, 2023	Dec. 31, 2022	Jan. 01, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 964	$ 962	$ 1,495
Foreign currency translation adjustments, pre-tax:
Foreign currency translation adjustment before tax	(446)	(412)	(222)
Net investment hedges gain (loss), pre-tax:
Net investment hedge gain (loss), pre-tax	(128)	287	236
Cash flow hedges, pre-tax:
Net deferred gain (loss) on cash flow hedges, pre-tax	(19)	221	38
Reclassifications to net income, pre-tax	9	(2)	22
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Net experience gain (loss)	0	5	(2)
Prior service credit (cost)	(15)	(3)	(18)
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience (gain) loss, pre-tax	(1)	(2)	(2)
Prior service (credit) cost, pre-tax	(1)	1	0
Available-for-sale securities, pre-tax
Unrealized gain (loss) on available-for-sale securities, pre-tax	1	(5)	(1)
Reclassification to net income on available-for-sale securities, pre-tax	3	1	(2)
Other comprehensive income (loss), pre-tax	(597)	91	49
Foreign Currency Translation Adjustment, tax (expense) benefit:
Foreign currency translation adjustments tax (expense) benefit	2	3	5
Net Investment Hedges, tax (expense) benefit
Net investment hedges gain (loss), tax (expense) benefit	32	(72)	(62)
Cash flow hedges, tax (expense) benefit:
Net deferred gain (loss) on cash flow hedges, tax (expense) benefit	5	(57)	(10)
Reclassification to net income, tax (expense) benefit	(2)	1	(6)
Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit:
Net experience gain (loss), tax (expense) benefit	0	(1)	1
Prior service credit (cost), tax (expense) benefit	8	1	4
Postretirement and postemployment benefits reclassification to net income, tax (expense) benefit:
Net experience (gain) loss, tax (expense) benefit	0	1	0
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	45	(124)	(68)
Foreign currency translation adjustments, after tax:
Foreign currency translation adjustments after tax	(444)	(409)	(217)
Net Investment Hedges, after tax:
Net investment hedges gain (loss), after-tax	(96)	215	174
Cash flow hedges, after-tax:
Net deferred gain (loss) on cash flow hedges, after-tax	(14)	164	28
Reclassification to net income, after-tax	7	(1)	16
Postretirement and postemployment benefit amounts arising during the period, after-tax
Net experience gain (loss), after tax	0	4	(1)
Prior service credit (cost), after-tax	(7)	(2)	(14)
Postretirement and postemployment benefits reclassification to net income, after-tax
Net experience loss, after-tax	(1)	(1)	(2)
Prior service cost, after-tax	(1)	1	0
Available-for-sale securities, after-tax
Unrealized gain (loss) on available-for-sale securities, after-tax	1	(5)	(1)
Reclassification to net income on available-for-sale securities, after-tax	3	1	(2)
Other comprehensive income (loss)	(552)	(33)	(19)
Comprehensive income	412	929	1,476
Net income (loss) attributable to noncontrolling interests	13	2	7
Other comprehensive income (loss) attributable to noncontrolling interests	(229)	(46)	(30)
Comprehensive income attributable to Kellanova	$ 628	$ 973	$ 1,499