CONSOLIDATED STATEMENT OF EQUITY (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Capital in excess of par value	Retained earnings	Treasury stock	Accumulated other comprehensive income (loss)	Total Kellanova equity	Non-controlling interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury Stock, Common, Shares					81
Balance (in shares) at Dec. 30, 2023		421
Balance at Dec. 30, 2023		$ 105	$ 1,101	$ 8,804	$ (4,794)	$ (2,041)	$ 3,175
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 30, 2023	$ 3,369							$ 194
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	271			267			267	4
Dividends, Common Stock	(191)			(191)			(191)
Distributions to noncontrolling interest	(2)						0	(2)
Other comprehensive income (loss)	(200)					(130)	(130)	(70)
Stock compensation	21		21				21
Stock options exercised, issuance of other stock awards and other	10		(59)	(2)	$ 71		10
Stock options exercised and other (in shares)					(1)
Balance (in shares) at Mar. 30, 2024		421
Balance at Mar. 30, 2024		$ 105	1,063	8,878	$ (4,723)	(2,171)	3,152
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 30, 2024	$ 3,278							126
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.56
Treasury Stock, Common, Shares					80
Treasury Stock, Common, Shares					76
Balance (in shares) at Dec. 28, 2024		421
Balance at Dec. 28, 2024	$ 3,775	$ 105	1,121	9,358	$ (4,533)	(2,276)	3,775
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 28, 2024	3,882							107
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	308			304			304	4
Dividends, Common Stock	(197)			(197)			(197)
Other comprehensive income (loss)	8					9	9	(1)
Stock compensation	22		22				22
Stock options exercised, issuance of other stock awards and other	2		(138)	32	$ 108		2
Stock options exercised and other (in shares)					(1)
Balance (in shares) at Mar. 29, 2025		421
Balance at Mar. 29, 2025	3,915	$ 105	$ 1,005	$ 9,497	$ (4,425)	$ (2,267)	$ 3,915
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 29, 2025	$ 4,025							$ 110
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.57
Treasury Stock, Common, Shares					75