CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2024	Sep. 30, 2023	Sep. 28, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 370	$ 270	$ 988	$ 934
Other comprehensive income (loss), pre-tax:
Foreign currency translation adjustments during period, pre-tax	94	(134)	(256)	(475)
Net investment hedges, pre-tax
Net investment hedge gain (loss), pre-tax	(133)	111	(34)	17
Cash flow hedges, pre-tax:
Net deferred gain (loss) on cash flow hedges, pre-tax	0	40	39	37
Reclassification to net income, pre-tax	0	2	3	7
Postretirement and postemployment benefit amounts arising during the period, pre-tax:
Prior service (credit) cost, pre-tax	1		2
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Net experience (gain) loss	(1)	(1)	(2)	(2)
Available-for-sale securities, pre-tax
Unrealized gain (loss) on available-for-sale securities, pre-tax		(1)		0
Reclassification to net income on available-for-sale securities, pre-tax		1		1
Other comprehensive income (loss), pre-tax	(39)	18	(248)	(415)
Other comprehensive income (loss), tax (expense) benefit
Foreign currency translation adjustments during period, tax (expense) benefit	0	1	0	3
Net investment hedges, tax (expense) benefit
Net investment hedge gain (loss), tax (expense) benefit	34	(26)	9	(4)
Cash flow hedges, tax (expense) benefit:
Net deferred gain (loss) on cash flow hedges, tax (expense) benefit	0	(10)	(10)	(9)
Reclassification to net income, tax (expense) benefit	0	(1)	(1)	(2)
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
Reclassification to net income on available for sale of securities, tax (expense) benefit		0		0
Other comprehensive income (loss), tax (expense) benefit	34	(36)	(2)	(12)
Other comprehensive income (loss), after tax:
Foreign currency translation adjustments during period, after-tax	94	(133)	(256)	(472)
Net investment hedges, after tax
Net investment hedge gain (loss), after-tax	(99)	85	(25)	13
Cash flow hedges, after tax
Net deferred gain (loss) on cash flow hedges	0	30	29	28
Reclassification to net income, after tax	0	1	2	5
Postretirement and postemployment benefit amounts arising during the period, after-tax:
Prior service (credit) cost, after-tax	1		2
Postretirement and postemployment benefits reclassification to net income, after-tax:
Net experience (gain) loss, after-tax	(1)	(1)	(2)	(2)
Available-for-sale securities, after tax
Unrealized gain (loss) on available-for-sale securities, after-tax		(1)		0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax		1		1
Other comprehensive income (loss)	(5)	(18)	(250)	(427)
Comprehensive income	365	252	738	507
Net income attributable to noncontrolling interests	3	1	10	10
Other comprehensive income (loss) attributable to noncontrolling interests	(15)	(7)	(93)	(181)
Comprehensive income attributable to Kellanova	$ 377	$ 258	$ 821	$ 678