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	424			422			422	2
Dividends, Common Stock	(197)			(197)			(197)
Distributions to noncontrolling interest	(1)						0	(1)
Other comprehensive income (loss)	114					110	110	4
Stock compensation	16		16				16
Stock options exercised, issuance of other stock awards and other	24		(46)	1	$ 69		24
Stock options exercised and other (in shares)					(2)
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 at Apr. 02, 2022	$ 4,295
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]
Net income	302			298			298	4
Dividends, Common Stock	(202)			(202)			(202)
Distributions to noncontrolling interest	(8)						0	(8)
Other comprehensive income (loss)	(8)					(5)	(5)	(3)
Stock compensation	22		22				22
Stock options exercised, issuance of other stock awards and other	(2)		(57)	0	$ 55		(2)
Stock options exercised and other (in shares)					(1)
Balance (in shares) at Apr. 01, 2023		421			78
Balance at Apr. 01, 2023	4,052	$ 105	$ 1,033	$ 9,293	$ (4,666)	$ (1,713)	$ 4,052	$ 427
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Apr. 01, 2023	$ 4,479
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared - per share	$ 0.59