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. 31, 2016	$ 1,907							$ 16
Balance, in shares at Dec. 31, 2016		420			69
Balance at Dec. 31, 2016		$ 105	$ 806	$ 6,552	$ (3,997)	$ (1,575)	$ 1,891
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchases	$ (516)				$ (516)		(516)
Common stock repurchases (in shares)	7				7
Net income (loss)	$ 1,254			1,254			1,254	0
Dividends declared ($2.26, $2.20, $2.12 per share for 2019, 2018 and 2017 respectively)	(736)			(736)			(736)
Other comprehensive income (loss)	118					118	118	0
Stock compensation	66		66				66
Stock options exercised and other	101		6	(1)	$ 96		101
Stock options exercised and other (in shares)		1			(1)
Balance, in shares at Dec. 30, 2017		421			75
Balance at Dec. 30, 2017		$ 105	878	7,069	$ (4,417)	(1,457)	2,178
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 30, 2017	2,194							16
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchases	$ (320)				$ (320)		(320)
Common stock repurchases (in shares)	5				5
Net income (loss)	$ 1,344			1,336			1,336	8
Acquisition of noncontrolling interest	552						0	552
Dividends declared ($2.26, $2.20, $2.12 per share for 2019, 2018 and 2017 respectively)	(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	2,601	$ 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 ($2.26, $2.20, $2.12 per share for 2019, 2018 and 2017 respectively)	(769)			(769)			(769)	0
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