CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 29, 2024	Jul. 01, 2023	Jun. 29, 2024	Jul. 01, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 347	$ 362	$ 618	$ 664
Other comprehensive income (loss), pre-tax:
Foreign currency translation adjustments during period, pre-tax	(78)	(383)	(350)	(341)
Net investment hedges, pre-tax
Net investment hedge gain (loss), pre-tax	28	(37)	99	(94)
Cash flow hedges, pre-tax:
Net deferred gain (loss) on cash flow hedges, pre-tax	17	15	39	(3)
Reclassification to net income, pre-tax	1	2	3	5
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Prior service (credit) cost, pre-tax	0		1
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience (gain) loss	(1)	0	(1)	(1)
Available-for-sale securities, pre-tax
Unrealized gain (loss) on available-for-sale securities, pre-tax		0		1
Other comprehensive income (loss), pre-tax	(33)	(403)	(209)	(433)
Other comprehensive income (loss), tax (expense) benefit
Foreign currency translation adjustments during period, tax (expense) benefit	0	(1)	0	2
Net investment hedges, tax (expense) benefit
Net investment hedge gain (loss), tax (expense) benefit	(7)	7	(25)	22
Cash flow hedges, tax (expense) benefit:
Net deferred gain (loss) on cash flow hedges, tax (expense) benefit	(4)	(4)	(10)	1
Reclassification to net income, tax (expense) benefit	(1)	0	(1)	(1)
Postretirement and postemployment benefit amounts arising during the period, tax (expense) benefit:
Prior service (credit) cost, tax (expense) benefit	0		0
Postretirement and postemployment benefits reclassification to net income, tax (expense) benefit:
Net experience loss, tax (expense) benefit	0	0	0	0
Available-for-sale securities, tax (expense) benefit
Unrealized gain (loss) on available-for-sale securities, tax (expense) benefit		0		0
Other comprehensive income (loss), tax (expense) benefit	(12)	2	(36)	24
Other comprehensive income (loss), after tax:
Foreign currency translation adjustments during period, after-tax	(78)	(384)	(350)	(339)
Net investment hedges, after tax
Net investment hedge gain (loss), after-tax	21	(30)	74	(72)
Cash flow hedges, after tax
Net deferred gain (loss) on cash flow hedges	13	11	29	(2)
Reclassification to net income, after tax	0	2	2	4
Postretirement and postemployment benefit amounts arising during the period, after-tax:
Prior service (credit) cost, after-tax	0		1
Postretirement and postemployment benefits reclassification to net income, after-tax:
Net experience (gain) loss, after-tax	(1)	0	(1)	(1)
Available-for-sale securities, after tax
Unrealized gain (loss) on available-for-sale securities, after-tax		0		1
Other comprehensive income (loss)	(45)	(401)	(245)	(409)
Comprehensive income	302	(39)	373	255
Net income attributable to noncontrolling interests	3	5	7	9
Other comprehensive income (loss) attributable to noncontrolling interests	(8)	(171)	(78)	(174)
Comprehensive income attributable to Kellanova	$ 307	$ 127	$ 444	$ 420