Consolidated Statement of Income (Unaudited) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2021	Sep. 26, 2020	Oct. 02, 2021	Sep. 26, 2020
Income Statement [Abstract]
Net sales	$ 3,622	$ 3,429	$ 10,761	$ 10,306
Cost of goods sold	2,457	2,228	7,206	6,764
Selling, general and administrative expense	718	790	2,132	2,166
Operating profit	447	411	1,423	1,376
Interest expense	55	63	172	196
Other income (expense), net	0	70	155	151
Income before income taxes	392	418	1,406	1,331
Income taxes	92	65	345	268
Earnings (loss) from unconsolidated entities	5	(1)	0	(7)
Net income	305	352	1,061	1,056
Net income attributable to noncontrolling interests	(2)	4	6	10
Net income attributable to Kellogg Company	$ 307	$ 348	$ 1,055	$ 1,046
Per share amounts:
Basic earnings (in dollars per share)	$ 0.90	$ 1.02	$ 3.09	$ 3.05
Diluted earnings (in dollars per share)	$ 0.89	$ 1.01	$ 3.07	$ 3.03
Average shares outstanding:
Basic (in shares)	341,000	343,000	341,000	343,000
Diluted (in shares)	343,000	346,000	343,000	345,000
Actual shares outstanding at period end (in shares)	341,000	344,000	341,000	344,000