Equity - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 03, 2015	Sep. 27, 2014	Oct. 03, 2015	Sep. 27, 2014
Equity [Abstract]
Net income attributable to Kellogg Company, Basic	$ 205	$ 224	$ 655	$ 925
Average shares outstanding, Basic (in shares)	354	358	354	359
Earnings per share, Basic (in dollars per share)	$ 0.58	$ 0.63	$ 1.85	$ 2.58
Average shares outstanding, Dilutive potential common shares (in shares)	2	2	2	2
Earnings per share, Dilutive potential common shares (in dollars per share)	$ 0.00	$ (0.01)	$ (0.01)	$ (0.02)
Net income attributable to Kellogg Company, Diluted	$ 205	$ 224	$ 655	$ 925
Average shares outstanding, Diluted (in shares)	356	360	356	361
Earnings per share, Diluted (in dollars per share)	$ 0.58	$ 0.62	$ 1.84	$ 2.56