Consolidated Statement of Income (Unaudited) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 03, 2021	Jun. 27, 2020	Jul. 03, 2021	Jun. 27, 2020
Income Statement [Abstract]
Net sales	$ 3,555	$ 3,465	$ 7,139	$ 6,877
Cost of goods sold	2,331	2,268	4,749	4,536
Selling, general and administrative expense	720	691	1,414	1,375
Operating profit	504	506	976	966
Interest expense	58	69	117	133
Other income (expense), net	86	30	155	79
Income before income taxes	532	467	1,014	912
Income taxes	144	109	253	203
Earnings (loss) from unconsolidated entities	(3)	(4)	(5)	(5)
Net income	385	354	756	704
Net income attributable to noncontrolling interests	5	3	8	6
Net income attributable to Kellogg Company	$ 380	$ 351	$ 748	$ 698
Per share amounts:
Basic earnings (in dollars per share)	$ 1.12	$ 1.02	$ 2.19	$ 2.04
Diluted earnings (in dollars per share)	$ 1.11	$ 1.02	$ 2.18	$ 2.02
Average shares outstanding:
Basic (in shares)	341,000	343,000	341,000	342,000
Diluted (in shares)	343,000	345,000	343,000	345,000
Actual shares outstanding at period end (in shares)	341,000	343,000	341,000	343,000