CONSOLIDATED STATEMENT OF EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common stock	Capital in excess of par value	Retained earnings	Treasury Stock, Common	Accumulated other comprehensive income (loss)	Total Kellanova equity	Non- controlling interests
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jan. 01, 2022	$ 4,215							$ 495
Balance, in shares at Jan. 01, 2022		421			80
Balance at Jan. 01, 2022		$ 105	$ 1,023	$ 9,028	$ (4,715)	$ (1,721)	$ 3,720
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchases	(300)				$ (300)		(300)
Common stock repurchases (in shares)					5
Net income (loss)	962			960			960	2
Dividends declared	(797)			(797)			(797)
Distributions to noncontrolling interest	(17)						0	(17)
Other comprehensive income (loss)	(33)					13	13	(46)
Stock compensation	96		96				96
Stock options exercised and other	249		(51)	6	$ 294		249
Stock options exercised and other (in shares)		0			(6)
Balance, in shares at Dec. 31, 2022		421			79
Balance at Dec. 31, 2022		$ 105	1,068	9,197	$ (4,721)	(1,708)	3,941
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2022	4,375							434
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchases	(170)				$ (170)		(170)
Common stock repurchases (in shares)					3
Net income (loss)	964			951			951	13
Dividends declared	(800)			(800)			(800)
Distributions to noncontrolling interest	(24)						0	(24)
Distribution of WK Kellogg Co.	(547)			(537)		(10)	(547)
Other comprehensive income (loss)	(552)					(323)	(323)	(229)
Stock compensation	95		95				95
Stock options exercised and other	28		(62)	(7)	$ 97		28
Stock options exercised and other (in shares)		0			(1)
Balance, in shares at Dec. 30, 2023		421			81
Balance at Dec. 30, 2023	3,175	$ 105	1,101	8,804	$ (4,794)	(2,041)	3,175
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 30, 2023	3,369							194
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchases	0				$ 0		0
Common stock repurchases (in shares)					0
Net income (loss)	1,356			1,343			1,343	13
Dividends declared	(776)			(776)			(776)
Distributions to noncontrolling interest	(7)						0	(7)
Other comprehensive income (loss)	(328)					(235)	(235)	(93)
Stock compensation	89		89				89
Stock options exercised and other	179		(69)	(13)	$ 261		179
Stock options exercised and other (in shares)		0			(5)
Balance, in shares at Dec. 28, 2024		421			76
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 at Dec. 28, 2024	$ 3,882							$ 107