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. 02, 2021	$ 3,636							$ 524
Balance, in shares at Jan. 02, 2021		421			77
Balance at Jan. 02, 2021		$ 105	$ 972	$ 8,326	$ (4,559)	$ (1,732)	$ 3,112
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchases	(240)				$ (240)		(240)
Common stock repurchases (in shares)					4
Net income (loss)	1,495			1,488			1,488	7
Noncontrolling Interest, Increase from Business Combination	52		22				22	30
Dividends declared	(788)			(788)			(788)
Distributions to noncontrolling interest	(36)						0	(36)
Other comprehensive income (loss)	(19)					11	11	(30)
Stock compensation	68		68				68
Stock options exercised and other	47		(39)	2	$ 84		47
Stock options exercised and other (in shares)		0			(1)
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
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jan. 01, 2022	4,215							495
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	3,941	$ 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)					(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