CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2025	Mar. 30, 2024
Statement of Comprehensive Income [Abstract]
Net income	$ 308	$ 271
Other comprehensive income (loss), pre-tax:
Foreign currency translation adjustments during period, pre-tax	81	(272)
Net investment hedges, pre-tax
Net investment hedge gain (loss), pre-tax	(97)	71
Cash flow hedges, pre-tax:
Net deferred gain (loss) on cash flow hedges, pre-tax		22
Reclassification to net income, pre-tax	(1)	2
Postretirement and postemployment benefits reclassification to net income, pre-tax:
Prior service (credit) cost, pre-tax	1	1
Other comprehensive income (loss), pre-tax	(16)	(176)
Other comprehensive income (loss), tax (expense) benefit
Foreign currency translation adjustments during period, tax (expense) benefit	0	0
Net investment hedges, tax (expense) benefit
Net investment hedge gain (loss), tax (expense) benefit	24	(18)
Cash flow hedges, tax (expense) benefit:
Net deferred gain (loss) on cash flow hedges, tax (expense) benefit		(6)
Reclassification to net income, tax (expense) benefit	0	0
Postretirement and postemployment benefits reclassification to net income, tax (expense) benefit:
Prior service cost, tax (expense) benefit	0	0
Other comprehensive income (loss), tax (expense) benefit	24	(24)
Other comprehensive income (loss), after tax:
Foreign currency translation adjustments during period, after-tax	81	(272)
Net investment hedges, after tax
Net investment hedge gain (loss), after-tax	(73)	53
Cash flow hedges, after tax
Net deferred gain (loss) on cash flow hedges		16
Reclassification to net income, after tax	(1)	2
Postretirement and postemployment benefits reclassification to net income, after-tax:
Prior service cost, after-tax	1	1
Other comprehensive income (loss)	8	(200)
Comprehensive income	316	71
Net income attributable to noncontrolling interests	4	4
Other comprehensive income (loss) attributable to noncontrolling interests	(1)	(70)
Comprehensive income attributable to Kellanova	$ 313	$ 137