CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 28, 2024	Dec. 30, 2023	Dec. 31, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 1,356	$ 964	$ 962
Foreign currency translation adjustments, pre-tax:
Foreign currency translation adjustment before tax	(488)	(446)	(412)
Net investment hedges gain (loss), pre-tax:
Net investment hedge gain (loss), pre-tax	178	(128)	287
Cash flow hedges, pre-tax:
Net deferred gain (loss) on cash flow hedges, pre-tax	39	(19)	221
Reclassifications to net income, pre-tax	3	9	(2)
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Net experience gain (loss)	(6)	0	5
Prior service credit (cost)	1	(15)	(3)
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience (gain) loss, pre-tax	(1)	(1)	(2)
Prior service (credit) cost, pre-tax	2	(1)	1
Available-for-sale securities, pre-tax
Unrealized gain (loss) on available-for-sale securities, pre-tax	0	1	(5)
Reclassification to net income on available-for-sale securities, pre-tax	0	3	1
Other comprehensive income (loss), pre-tax	(272)	(597)	91
Foreign Currency Translation Adjustment, tax (expense) benefit:
Foreign currency translation adjustments tax (expense) benefit	0	2	3
Net Investment Hedges, tax (expense) benefit
Net investment hedges gain (loss), tax (expense) benefit	(46)	32	(72)
Cash flow hedges, tax (expense) benefit:
Net deferred gain (loss) on cash flow hedges, tax (expense) benefit	(10)	5	(57)
Reclassification to net income, tax (expense) benefit	(1)	(2)	1
Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit:
Net experience gain (loss), tax (expense) benefit	2	0	(1)
Prior service credit (cost), tax (expense) benefit	0	8	1
Postretirement and postemployment benefits reclassification to net income, tax (expense) benefit:
Net experience (gain) loss, tax (expense) benefit	0	0	1
Prior service (credit) cost, tax (expense) benefit	(1)	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	(56)	45	(124)
Foreign currency translation adjustments, after tax:
Foreign currency translation adjustments after tax	(488)	(444)	(409)
Net Investment Hedges, after tax:
Net investment hedges gain (loss), after-tax	132	(96)	215
Cash flow hedges, after-tax:
Net deferred gain (loss) on cash flow hedges, after-tax	29	(14)	164
Reclassification to net income, after-tax	2	7	(1)
Postretirement and postemployment benefit amounts arising during the period, after-tax
Net experience gain (loss), after tax	(4)	0	4
Prior service credit (cost), after-tax	1	(7)	(2)
Postretirement and postemployment benefits reclassification to net income, after-tax
Net experience loss, after-tax	(1)	(1)	(1)
Prior service cost, after-tax	1	(1)	1
Available-for-sale securities, after-tax
Unrealized gain (loss) on available-for-sale securities, after-tax	0	1	(5)
Reclassification to net income on available-for-sale securities, after-tax	0	3	1
Other comprehensive income (loss)	(328)	(552)	(33)
Comprehensive income	1,028	412	929
Net income (loss) attributable to noncontrolling interests	13	13	2
Other comprehensive income (loss) attributable to noncontrolling interests	(93)	(229)	(46)
Comprehensive income attributable to Kellanova	$ 1,108	$ 628	$ 973