Equity - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2016	Oct. 03, 2015	Oct. 01, 2016	Oct. 03, 2015
Equity [Abstract]
Net income attributable to Kellogg Company, Basic	$ 292	$ 205	$ 747	$ 655
Average shares outstanding, Basic (in shares)	350	354	350	354
Earnings per share, Basic (in dollars per share)	$ 0.83	$ 0.58	$ 2.13	$ 1.85
Average shares outstanding, Dilutive potential common shares (in shares)	4	2	4	2
Earnings per share, Dilutive potential common shares (in dollars per share)	$ (0.01)	$ 0.00	$ (0.02)	$ (0.01)
Net income attributable to Kellogg Company, Diluted	$ 292	$ 205	$ 747	$ 655
Average shares outstanding, Diluted (in shares)	354	356	354	356
Earnings per share, Diluted (in dollars per share)	$ 0.82	$ 0.58	$ 2.11	$ 1.84