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 Dec. 28, 2019		421			79
Balance at Dec. 28, 2019		$ 105	$ 921	$ 7,859	$ (4,690)	$ (1,448)	$ 2,747	$ 567
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 28, 2019	$ 3,314
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	350			347			347	3
Dividends, Common Stock	(195)			(195)			(195)
Other comprehensive income (loss)	(311)					(279)	(279)	(32)
Stock compensation	19		19				19
Stock options exercised and other	35		(29)	(1)	$ 65		35
Stock options exercised and other (in shares)					(1)
Balance (in shares) at Mar. 28, 2020		421			78
Balance at Mar. 28, 2020		$ 105	911	8,010	$ (4,625)	(1,727)	2,674	538
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 28, 2020	3,212
Balance (in shares) at Jan. 02, 2021		421			77
Balance at Jan. 02, 2021	3,112	$ 105	972	8,326	$ (4,559)	(1,732)	3,112	524
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Jan. 02, 2021	3,636
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased	$ (240)				$ (240)		(240)
Common stock repurchased (in shares)	4				4
Net income	$ 371			368			368	3
Dividends, Common Stock	(195)			(195)			(195)
Other comprehensive income (loss)	57					67	67	(10)
Stock compensation	20		20				20
Stock options exercised and other	6		(38)	7	$ 37		6
Stock options exercised and other (in shares)					0
Balance (in shares) at Apr. 03, 2021		421			81
Balance at Apr. 03, 2021	3,138	$ 105	$ 954	$ 8,506	$ (4,762)	$ (1,665)	$ 3,138	$ 517
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Apr. 03, 2021	$ 3,655