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	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
Balance at Sep. 28, 2024		$ 105	1,105	9,195	$ (4,557)	(2,198)	3,650
Stockholders' equity, including portion attributable to noncontrolling interest, ending balance at Sep. 28, 2024	$ 3,758							108
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 1.69
Treasury Stock, Common, Shares					79
Balance (in shares) at Jun. 29, 2024		421
Balance at Jun. 29, 2024		$ 105	1,082	9,027	$ (4,699)	(2,208)	3,307
Stockholders' equity, including portion attributable to noncontrolling interest, beginning balance at Jun. 29, 2024	$ 3,427							120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	370			367			367	3
Dividends, Common Stock	(197)			(197)			(197)
Distributions to noncontrolling interest	0						0	0
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
Balance at Sep. 28, 2024		$ 105	1,105	9,195	$ (4,557)	(2,198)	3,650
Stockholders' equity, including portion attributable to noncontrolling interest, ending balance at Sep. 28, 2024	$ 3,758							108
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.57
Treasury Stock, Common, Shares					77
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	925			912			912	13
Disposition of noncontrolling interest	(4)						0	(4)
Dividends, Common Stock	(598)			(598)			(598)
Distributions to noncontrolling interest	(26)						0	(26)
Other comprehensive income (loss)	42					40	40	2
Stock compensation	31		31				31
Stock options exercised, issuance of other stock awards and other	43		(145)	24	$ 164		43
Stock options exercised and other (in shares)					(3)
Balance (in shares) at Sep. 27, 2025		421
Balance at Sep. 27, 2025	4,203	$ 105	1,007	9,696	$ (4,369)	(2,236)	4,203
Stockholders' equity, including portion attributable to noncontrolling interest, ending balance at Sep. 27, 2025	$ 4,295							92
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 1.72
Treasury Stock, Common, Shares					74
Balance (in shares) at Jun. 28, 2025		421
Balance at Jun. 28, 2025		$ 105	1,016	9,590	$ (4,384)	(2,218)	4,109
Stockholders' equity, including portion attributable to noncontrolling interest, beginning balance at Jun. 28, 2025	$ 4,210							101
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	314			309			309	5
Disposition of noncontrolling interest	0						0	0
Dividends, Common Stock	(203)			(203)			(203)
Distributions to noncontrolling interest	(12)						0	(12)
Other comprehensive income (loss)	(20)					(18)	(18)	(2)
Stock compensation	(5)		(5)				(5)
Stock options exercised, issuance of other stock awards and other	11		(4)	0	$ 15		11
Stock options exercised and other (in shares)					(1)
Balance (in shares) at Sep. 27, 2025		421
Balance at Sep. 27, 2025	4,203	$ 105	$ 1,007	$ 9,696	$ (4,369)	$ (2,236)	$ 4,203
Stockholders' equity, including portion attributable to noncontrolling interest, ending balance at Sep. 27, 2025	$ 4,295							$ 92
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.58
Treasury Stock, Common, Shares					73