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
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	$ 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		$ 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]
Net income	270			269			269	1
Dividends, Common Stock	(206)			(206)			(206)
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	2		(5)	(1)	$ 8		2
Stock options exercised and other (in shares)					0
Balance (in shares) at Sep. 30, 2023		421			79
Balance at Sep. 30, 2023		$ 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
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	194
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 30, 2023	3,369
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	988			978			978	10
Dividends, Common Stock	(580)			(580)			(580)
Distributions to noncontrolling interest	(3)						0	(3)
Other comprehensive income (loss)	(250)					(157)	(157)	(93)
Stock compensation	66		66				66
Stock options exercised, issuance of other stock awards and other	168		(62)	(7)	$ 237		168
Stock options exercised and other (in shares)					(4)
Balance (in shares) at Sep. 28, 2024		421			77
Balance at Sep. 28, 2024	3,650	$ 105	1,105	9,195	$ (4,557)	(2,198)	3,650	108
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Sep. 28, 2024	$ 3,758
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 1.69
Balance (in shares) at Jun. 29, 2024		421			79
Balance at Jun. 29, 2024		$ 105	1,082	9,027	$ (4,699)	(2,208)	3,307	120
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Jun. 29, 2024	$ 3,427
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	370			367			367	3
Dividends, Common Stock	(197)			(197)			(197)
Other comprehensive income (loss)	(5)					10	10	(15)
Stock compensation	25		25				25
Stock options exercised, issuance of other stock awards and other	138		(2)	(2)	$ 142		138
Stock options exercised and other (in shares)					(2)
Balance (in shares) at Sep. 28, 2024		421			77
Balance at Sep. 28, 2024	3,650	$ 105	$ 1,105	$ 9,195	$ (4,557)	$ (2,198)	$ 3,650	$ 108
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Sep. 28, 2024	$ 3,758
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.57