Statement of Shareholders' Equity - 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
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 30, 2017	$ 2,194							$ 16
Balance, in shares at Dec. 30, 2017		421			75
Balance at Dec. 30, 2017		$ 105	$ 878	$ 7,069	$ (4,417)	$ (1,457)	$ 2,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchases	(320)				$ (320)		(320)
Common stock repurchases (in shares)					5
Net income (loss)	1,344			1,336			1,336	8
Acquisition of noncontrolling interest	552						0	552
Dividends declared	(762)			(762)			(762)
Distributions to noncontrolling interest	(11)						0	(11)
Other comprehensive income (loss)	(50)					(43)	(43)	(7)
Stock compensation	59		59				59
Stock options exercised and other	153		(42)	9	$ 186		153
Stock options exercised and other (in shares)		0			(3)
Balance, in shares at Dec. 29, 2018		421			77
Balance at Dec. 29, 2018		$ 105	895	7,652	$ (4,551)	(1,500)	2,601
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 29, 2018	3,159							558
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchases	$ (220)				$ (220)		(220)
Common stock repurchases (in shares)	4				4
Net income (loss)	$ 977			960			960	17
Sale of subsidiary shares to noncontrolling interest	1						0	1
Dividends declared	(769)			(769)			(769)
Distributions to noncontrolling interest	(9)						0	(9)
Other comprehensive income (loss)	74					74	74	0
Reclassification of tax effects relating to U.S. Tax Reform	0			22		(22)	0
Stock compensation	56		56				56
Stock options exercised and other	45		(30)	(6)	$ 81		45
Stock options exercised and other (in shares)		0			(2)
Balance, in shares at Dec. 28, 2019		421			79
Balance at Dec. 28, 2019	2,747	$ 105	921	7,859	$ (4,690)	(1,448)	2,747
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 28, 2019	3,314							567
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,264			1,251			1,251	13
Divestiture	(3)						0	(3)
Dividends declared	(782)			(782)			(782)	0
Distributions to noncontrolling interest	(1)						0	(1)
Other comprehensive income (loss)	(336)					(284)	(284)	(52)
Stock compensation	76		76				76
Stock options exercised and other	104		(25)	(2)	$ 131		104
Stock options exercised and other (in shares)		0			(2)
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
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jan. 02, 2021	$ 3,636							$ 524