Consolidated Statement of Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common stock	Capital in excess of par value	Retained earnings	Treasury stock	Accumulated other comprehensive income (loss)	Total Kellanova equity	Non-controlling interests
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	$ 495
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Jan. 01, 2022	$ 4,215
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased	(300)				$ (300)		(300)
Common stock repurchased (in shares)					5
Net income	1,062			1,058			1,058	4
Dividends, Common Stock	(596)			(596)			(596)
Distributions to noncontrolling interest	(18)						0	(18)
Other comprehensive income (loss)	97					123	123	(26)
Stock compensation	56		56				56
Stock options exercised, issuance of other stock awards and other	222		(52)	9	$ 265		222
Stock options exercised and other (in shares)					(5)
Balance (in shares) at Oct. 01, 2022		421			80
Balance at Oct. 01, 2022		$ 105	1,027	9,499	$ (4,750)	(1,598)	4,283	455
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Oct. 01, 2022	$ 4,738
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 1.75
Balance (in shares) at Jul. 02, 2022		421			81
Balance at Jul. 02, 2022		$ 105	1,008	9,387	$ (4,817)	(1,601)	4,082	476
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Jul. 02, 2022	$ 4,558
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	312			310			310	2
Dividends, Common Stock	(202)			(202)			(202)
Distributions to noncontrolling interest	(1)						0	(1)
Other comprehensive income (loss)	(19)					3	3	(22)
Stock compensation	21		21				21
Stock options exercised, issuance of other stock awards and other	69		(2)	4	$ 67		69
Stock options exercised and other (in shares)					(1)
Balance (in shares) at Oct. 01, 2022		421			80
Balance at Oct. 01, 2022		$ 105	1,027	9,499	$ (4,750)	(1,598)	4,283	455
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Oct. 01, 2022	$ 4,738
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.59
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	434
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2022	4,375
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased	(60)				$ (60)		(60)
Common stock repurchased (in shares)					1
Net income	934			924			924	10
Dividends, Common Stock	(610)			(610)			(610)
Distributions to noncontrolling interest	(24)						0	(24)
Other comprehensive income (loss)	(427)					(246)	(246)	(181)
Stock compensation	62		62				62
Stock options exercised, issuance of other stock awards and other	27		(60)	(2)	$ 89		27
Stock options exercised and other (in shares)					(1)
Balance (in shares) at Sep. 30, 2023		421			79
Balance at Sep. 30, 2023	4,038	$ 105	1,070	9,509	$ (4,692)	(1,954)	4,038	239
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Sep. 30, 2023	$ 4,277
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 1.78
Balance (in shares) at Jul. 01, 2023		421			79
Balance at Jul. 01, 2023		$ 105	1,056	9,447	$ (4,700)	(1,943)	3,965	256
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Jul. 01, 2023	$ 4,221
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased	0				$ 0		0
Common stock repurchased (in shares)					0
Net income	270			269			269	1
Dividends, Common Stock	(205)			(205)			(205)
Distributions to noncontrolling interest	(11)						0	(11)
Other comprehensive income (loss)	(18)					(11)	(11)	(7)
Stock compensation	19		19				19
Stock options exercised, issuance of other stock awards and other	1		(5)	(2)	$ 8		1
Stock options exercised and other (in shares)					0
Balance (in shares) at Sep. 30, 2023		421			79
Balance at Sep. 30, 2023	4,038	$ 105	$ 1,070	$ 9,509	$ (4,692)	$ (1,954)	$ 4,038	$ 239
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Sep. 30, 2023	$ 4,277
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.60