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 Kellogg Company 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	750			748			748	2
Dividends, Common Stock	(394)			(394)			(394)
Distributions to noncontrolling interest	(17)						0	(17)
Other comprehensive income (loss)	116					120	120	(4)
Stock compensation	35		35				35
Stock options exercised, issuance of other stock awards and other	153		(50)	5	$ 198		153
Stock options exercised and other (in shares)					(4)
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 at Jul. 02, 2022	$ 4,558
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 1.16
Balance (in shares) at Apr. 02, 2022		421			83
Balance at Apr. 02, 2022		$ 105	993	9,254	$ (4,946)	(1,611)	3,795	500
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Apr. 02, 2022	$ 4,295
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	326			326			326	0
Dividends, Common Stock	(197)			(197)			(197)
Distributions to noncontrolling interest	(16)						0	(16)
Other comprehensive income (loss)	2					10	10	(8)
Stock compensation	19		19				19
Stock options exercised, issuance of other stock awards and other	129		(4)	4	$ 129		129
Stock options exercised and other (in shares)					(2)
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 at Jul. 02, 2022	$ 4,558
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.58
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	664			655			655	9
Dividends, Common Stock	(404)			(404)			(404)
Distributions to noncontrolling interest	(13)						0	(13)
Other comprehensive income (loss)	(409)					(235)	(235)	(174)
Stock compensation	43		43				43
Stock options exercised, issuance of other stock awards and other	25		(55)	(1)	$ 81		25
Stock options exercised and other (in shares)					(1)
Balance (in shares) at Jul. 01, 2023		421			79
Balance at Jul. 01, 2023	3,965	$ 105	1,056	9,447	$ (4,700)	(1,943)	3,965	256
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jul. 01, 2023	$ 4,221
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 1.18
Balance (in shares) at Apr. 01, 2023		421			78
Balance at Apr. 01, 2023		$ 105	1,033	9,293	$ (4,666)	(1,713)	4,052	427
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Apr. 01, 2023	$ 4,479
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased	(60)				$ (60)		(60)
Common stock repurchased (in shares)					1
Net income	362			357			357	5
Dividends, Common Stock	(202)			(202)			(202)
Distributions to noncontrolling interest	(5)						0	(5)
Other comprehensive income (loss)	(401)					(230)	(230)	(171)
Stock compensation	21		21				21
Stock options exercised, issuance of other stock awards and other	27		2	(1)	$ 26		27
Stock options exercised and other (in shares)					0
Balance (in shares) at Jul. 01, 2023		421			79
Balance at Jul. 01, 2023	3,965	$ 105	$ 1,056	$ 9,447	$ (4,700)	$ (1,943)	$ 3,965	$ 256
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jul. 01, 2023	$ 4,221
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.59